System for managing development buildouts

## Project description

Buildout is a project designed to solve 2 problems:

1. Application-centric assembly and deployment

Assembly runs the gamut from stitching together libraries to create a running program, to production deployment configuration of applications, and associated systems and tools (e.g. run-control scripts, cron jobs, logs, service registration, etc.).

Buildout might be confused with build tools like make or ant, but it is a little higher level and might invoke systems like make or ant to get it’s work done.

Buildout might be confused with systems like puppet or chef, but it is more application focused. Systems like puppet or chef might use buildout to get their work done.

Buildout is also somewhat Python-centric, even though it can be used to assemble and deploy non-python applications. It has some special features for assembling Python programs. It’s scripted with Python, unlike, say puppet or chef, which are scripted with Ruby.

2. Repeatable assembly of programs from Python software distributions

Buildout puts great effort toward making program assembly a highly repeatable process, whether in a very open-ended development mode, where dependency versions aren’t locked down, or in a deployment environment where dependency versions are fully specified. You should be able to check buildout into a VCS and later check it out. Two checkouts built at the same time in the same environment should always give the same result, regardless of their history. Among other things, after a buildout, all dependencies should be at the most recent version consistent with any version specifications expressed in the buildout.

Buildout supports applications consisting of multiple programs, with different programs in an application free to use different versions of Python distributions. This is in contrast with a Python installation (real or virtual), where, for any given distribution, there can only be one installed.

This version of buildout is available from the github project download page, not from pypi.

To get the bootstrap.py file for this release of buildout, get https://github.com/downloads/buildout/buildout/bootstrap.py.

For example, using wget:

Since this is still an alpha release, you’ll need to supply the -t option to bootstrap.py:

python bootstrap.py -t


This version of buildout support Python 2.6, 2.7, 3.2 and 3.3.

Below, you’ll find doctest-based documentation. It was an experiment in reusing tests as documentation. The experiment didn’t go that well, but there may be details below that aren’t easy to find on buildout.org yet.

## doctest-based Documentation

### Buildouts

The word “buildout” refers to a description of a set of parts and the software to create and assemble them. It is often used informally to refer to an installed system based on a buildout definition. For example, if we are creating an application named “Foo”, then “the Foo buildout” is the collection of configuration and application-specific software that allows an instance of the application to be created. We may refer to such an instance of the application informally as “a Foo buildout”.

This document describes how to define buildouts using buildout configuration files and recipes. There are three ways to set up the buildout software and create a buildout instance:

1. Install the zc.buildout egg with easy_install and use the buildout script installed in a Python scripts area.
2. Use the buildout bootstrap script to create a buildout that includes both the distribute and zc.buildout eggs. This allows you to use the buildout software without modifying a Python install. The buildout script is installed into your buildout local scripts area.
3. Use a buildout command from an already installed buildout to bootstrap a new buildout. (See the section on bootstraping later in this document.)

Often, a software project will be managed in a software repository, such as a subversion repository, that includes some software source directories, buildout configuration files, and a copy of the buildout bootstrap script. To work on the project, one would check out the project from the repository and run the bootstrap script which installs distribute and zc.buildout into the checkout as well as any parts defined.

We have a sample buildout that we created using the bootstrap command of an existing buildout (method 3 above). It has the absolute minimum information. We have bin, develop-eggs, eggs and parts directories, and a configuration file:

>>> ls(sample_buildout)
d  bin
-  buildout.cfg
d  develop-eggs
d  eggs
d  parts


The bin directory contains scripts.

>>> ls(sample_buildout, 'bin')
-  buildout

>>> ls(sample_buildout, 'eggs')
-  distribute-0.6-py2.4.egg
-  zc.buildout-1.0-py2.4.egg


The develop-eggs and parts directories are initially empty:

>>> ls(sample_buildout, 'develop-eggs')
>>> ls(sample_buildout, 'parts')


The develop-eggs directory holds egg links for software being developed in the buildout. We separate develop-eggs and other eggs to allow eggs directories to be shared across multiple buildouts. For example, a common developer technique is to define a common eggs directory in their home that all non-develop eggs are stored in. This allows larger buildouts to be set up much more quickly and saves disk space.

The parts directory provides an area where recipes can install part data. For example, if we built a custom Python, we would install it in the part directory. Part data is stored in a sub-directory of the parts directory with the same name as the part.

Buildouts are defined using configuration files. These are in the format defined by the Python ConfigParser module, with extensions that we’ll describe later. By default, when a buildout is run, it looks for the file buildout.cfg in the directory where the buildout is run.

The minimal configuration file has a buildout section that defines no parts:

>>> cat(sample_buildout, 'buildout.cfg')
[buildout]
parts =


A part is simply something to be created by a buildout. It can be almost anything, such as a Python package, a program, a directory, or even a configuration file.

#### Recipes

A part is created by a recipe. Recipes are always installed as Python eggs. They can be downloaded from a package server, such as the Python Package Index, or they can be developed as part of a project using a “develop” egg.

A develop egg is a special kind of egg that gets installed as an “egg link” that contains the name of a source directory. Develop eggs don’t have to be packaged for distribution to be used and can be modified in place, which is especially useful while they are being developed.

Let’s create a recipe as part of the sample project. We’ll create a recipe for creating directories. First, we’ll create a recipes source directory for our local recipes:

>>> mkdir(sample_buildout, 'recipes')


and then we’ll create a source file for our mkdir recipe:

>>> write(sample_buildout, 'recipes', 'mkdir.py',
... """
... import logging, os, zc.buildout
...
... class Mkdir:
...
...     def __init__(self, buildout, name, options):
...         self.name, self.options = name, options
...         options['path'] = os.path.join(
...                               buildout['buildout']['directory'],
...                               options['path'],
...                               )
...         if not os.path.isdir(os.path.dirname(options['path'])):
...             logging.getLogger(self.name).error(
...                 'Cannot create %s. %s is not a directory.',
...                 options['path'], os.path.dirname(options['path']))
...             raise zc.buildout.UserError('Invalid Path')
...
...
...     def install(self):
...         path = self.options['path']
...         logging.getLogger(self.name).info(
...             'Creating directory %s', os.path.basename(path))
...         os.mkdir(path)
...         return path
...
...     def update(self):
...         pass
... """)


Currently, recipes must define 3 methods:

• a constructor,
• an install method, and
• an update method.

The constructor is responsible for updating a parts options to reflect data read from other sections. The buildout system keeps track of whether a part specification has changed. A part specification has changed if it’s options, after adjusting for data read from other sections, has changed, or if the recipe has changed. Only the options for the part are considered. If data are read from other sections, then that information has to be reflected in the parts options. In the Mkdir example, the given path is interpreted relative to the buildout directory, and data from the buildout directory is read. The path option is updated to reflect this. If the directory option was changed in the buildout sections, we would know to update parts created using the mkdir recipe using relative path names.

When buildout is run, it saves configuration data for installed parts in a file named “.installed.cfg”. In subsequent runs, it compares part-configuration data stored in the .installed.cfg file and the part-configuration data loaded from the configuration files as modified by recipe constructors to decide if the configuration of a part has changed. If the configuration has changed, or if the recipe has changed, then the part is uninstalled and reinstalled. The buildout only looks at the part’s options, so any data used to configure the part needs to be reflected in the part’s options. It is the job of a recipe constructor to make sure that the options include all relevant data.

Of course, parts are also uninstalled if they are no-longer used.

The recipe defines a constructor that takes a buildout object, a part name, and an options dictionary. It saves them in instance attributes. If the path is relative, we’ll interpret it as relative to the buildout directory. The buildout object passed in is a mapping from section name to a mapping of options for that section. The buildout directory is available as the directory option of the buildout section. We normalize the path and save it back into the options directory.

The install method is responsible for creating the part. In this case, we need the path of the directory to create. We’ll use a path option from our options dictionary. The install method logs what it’s doing using the Python logging call. We return the path that we installed. If the part is uninstalled or reinstalled, then the path returned will be removed by the buildout machinery. A recipe install method is expected to return a string, or an iterable of strings containing paths to be removed if a part is uninstalled. For most recipes, this is all of the uninstall support needed. For more complex uninstallation scenarios use Uninstall recipes.

The update method is responsible for updating an already installed part. An empty method is often provided, as in this example, if parts can’t be updated. An update method can return None, a string, or an iterable of strings. If a string or iterable of strings is returned, then the saved list of paths to be uninstalled is updated with the new information by adding any new files returned by the update method.

We need to provide packaging information so that our recipe can be installed as a develop egg. The minimum information we need to specify is a name. For recipes, we also need to define the names of the recipe classes as entry points. Packaging information is provided via a setup.py script:

>>> write(sample_buildout, 'recipes', 'setup.py',
... """
... from setuptools import setup
...
... setup(
...     name = "recipes",
...     entry_points = {'zc.buildout': ['mkdir = mkdir:Mkdir']},
...     )
... """)


Our setup script defines an entry point. Entry points provide a way for an egg to define the services it provides. Here we’ve said that we define a zc.buildout entry point named mkdir. Recipe classes must be exposed as entry points in the zc.buildout group. we give entry points names within the group.

We also need a README.txt for our recipes to avoid an annoying warning from distutils, on which distribute and zc.buildout are based:

>>> write(sample_buildout, 'recipes', 'README.txt', " ")


Now let’s update our buildout.cfg:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir
...
... [data-dir]
... recipe = recipes:mkdir
... path = mystuff
... """)


Let’s go through the changes one by one:

develop = recipes


This tells the buildout to install a development egg for our recipes. Any number of paths can be listed. The paths can be relative or absolute. If relative, they are treated as relative to the buildout directory. They can be directory or file paths. If a file path is given, it should point to a Python setup script. If a directory path is given, it should point to a directory containing a setup.py file. Development eggs are installed before building any parts, as they may provide locally-defined recipes needed by the parts.

parts = data-dir


Here we’ve named a part to be “built”. We can use any name we want except that different part names must be unique and recipes will often use the part name to decide what to do.

[data-dir]
recipe = recipes:mkdir
path = mystuff


When we name a part, we also create a section of the same name that contains part data. In this section, we’ll define the recipe to be used to install the part. In this case, we also specify the path to be created.

Let’s run the buildout. We do so by running the build script in the buildout:

>>> import os
>>> os.chdir(sample_buildout)
>>> buildout = os.path.join(sample_buildout, 'bin', 'buildout')
>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
Installing data-dir.
data-dir: Creating directory mystuff


We see that the recipe created the directory, as expected:

>>> ls(sample_buildout)
-  .installed.cfg
d  bin
-  buildout.cfg
d  develop-eggs
d  eggs
d  mystuff
d  parts
d  recipes


In addition, .installed.cfg has been created containing information about the part we installed:

>>> cat(sample_buildout, '.installed.cfg')
[buildout]
parts = data-dir
<BLANKLINE>
[data-dir]
__buildout_installed__ = /sample-buildout/mystuff
__buildout_signature__ = recipes-c7vHV6ekIDUPy/7fjAaYjg==
path = /sample-buildout/mystuff
recipe = recipes:mkdir


Note that the directory we installed is included in .installed.cfg. In addition, the path option includes the actual destination directory.

If we change the name of the directory in the configuration file, we’ll see that the directory gets removed and recreated:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir
...
... [data-dir]
... recipe = recipes:mkdir
... path = mydata
... """)

>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
Uninstalling data-dir.
Installing data-dir.
data-dir: Creating directory mydata

>>> ls(sample_buildout)
-  .installed.cfg
d  bin
-  buildout.cfg
d  develop-eggs
d  eggs
d  mydata
d  parts
d  recipes


If any of the files or directories created by a recipe are removed, the part will be reinstalled:

>>> rmdir(sample_buildout, 'mydata')
>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
Uninstalling data-dir.
Installing data-dir.
data-dir: Creating directory mydata


#### Error reporting

If a user makes an error, an error needs to be printed and work needs to stop. This is accomplished by logging a detailed error message and then raising a (or an instance of a subclass of a) zc.buildout.UserError exception. Raising an error other than a UserError still displays the error, but labels it as a bug in the buildout software or recipe. In the sample above, of someone gives a non-existent directory to create the directory in:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir
...
... [data-dir]
... recipe = recipes:mkdir
... path = /xxx/mydata
... """)


We’ll get a user error, not a traceback.

>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
data-dir: Cannot create /xxx/mydata. /xxx is not a directory.
While:
Installing.
Getting section data-dir.
Initializing part data-dir.
Error: Invalid Path


#### Recipe Error Handling

If an error occurs during installation, it is up to the recipe to clean up any system side effects, such as files created. Let’s update the mkdir recipe to support multiple paths:

>>> write(sample_buildout, 'recipes', 'mkdir.py',
... """
... import logging, os, zc.buildout
...
... class Mkdir:
...
...     def __init__(self, buildout, name, options):
...         self.name, self.options = name, options
...
...         # Normalize paths and check that their parent
...         # directories exist:
...         paths = []
...         for path in options['path'].split():
...             path = os.path.join(buildout['buildout']['directory'], path)
...             if not os.path.isdir(os.path.dirname(path)):
...                 logging.getLogger(self.name).error(
...                     'Cannot create %s. %s is not a directory.',
...                     options['path'], os.path.dirname(options['path']))
...                 raise zc.buildout.UserError('Invalid Path')
...             paths.append(path)
...         options['path'] = ' '.join(paths)
...
...     def install(self):
...         paths = self.options['path'].split()
...         for path in paths:
...             logging.getLogger(self.name).info(
...                 'Creating directory %s', os.path.basename(path))
...             os.mkdir(path)
...         return paths
...
...     def update(self):
...         pass
... """)

>>> clean_up_pyc(sample_buildout, 'recipes', 'mkdir.py')


If there is an error creating a path, the install method will exit and leave previously created paths in place:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir
...
... [data-dir]
... recipe = recipes:mkdir
... path = foo bin
... """)

>>> print_(system(buildout)) # doctest: +ELLIPSIS
Develop: '/sample-buildout/recipes'
Uninstalling data-dir.
Installing data-dir.
data-dir: Creating directory foo
data-dir: Creating directory bin
While:
Installing data-dir.
<BLANKLINE>
An internal error occured due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
... exists...


We meant to create a directory bins, but typed bin. Now foo was left behind.

>>> os.path.exists('foo')
True


If we fix the typo:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir
...
... [data-dir]
... recipe = recipes:mkdir
... path = foo bins
... """)

>>> print_(system(buildout)) # doctest: +ELLIPSIS
Develop: '/sample-buildout/recipes'
Installing data-dir.
data-dir: Creating directory foo
While:
Installing data-dir.
<BLANKLINE>
An internal error occured due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
... exists...


Now they fail because foo exists, because it was left behind.

>>> remove('foo')


Let’s fix the recipe:

>>> write(sample_buildout, 'recipes', 'mkdir.py',
... """
... import logging, os, zc.buildout, sys
...
... class Mkdir:
...
...     def __init__(self, buildout, name, options):
...         self.name, self.options = name, options
...
...         # Normalize paths and check that their parent
...         # directories exist:
...         paths = []
...         for path in options['path'].split():
...             path = os.path.join(buildout['buildout']['directory'], path)
...             if not os.path.isdir(os.path.dirname(path)):
...                 logging.getLogger(self.name).error(
...                     'Cannot create %s. %s is not a directory.',
...                     options['path'], os.path.dirname(options['path']))
...                 raise zc.buildout.UserError('Invalid Path')
...             paths.append(path)
...         options['path'] = ' '.join(paths)
...
...     def install(self):
...         paths = self.options['path'].split()
...         created = []
...         try:
...             for path in paths:
...                 logging.getLogger(self.name).info(
...                     'Creating directory %s', os.path.basename(path))
...                 os.mkdir(path)
...                 created.append(path)
...         except Exception:
...             for d in created:
...                 os.rmdir(d)
...                 assert not os.path.exists(d)
...                 logging.getLogger(self.name).info(
...                     'Removed %s due to error',
...                      os.path.basename(d))
...             sys.stderr.flush()
...             sys.stdout.flush()
...             raise
...
...         return paths
...
...     def update(self):
...         pass
... """)

>>> clean_up_pyc(sample_buildout, 'recipes', 'mkdir.py')


And put back the typo:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir
...
... [data-dir]
... recipe = recipes:mkdir
... path = foo bin
... """)


When we rerun the buildout:

>>> print_(system(buildout)) # doctest: +ELLIPSIS
Develop: '/sample-buildout/recipes'
Installing data-dir.
data-dir: Creating directory foo
data-dir: Creating directory bin
data-dir: Removed foo due to error
While:
Installing data-dir.
<BLANKLINE>
An internal error occured due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
... exists...


we get the same error, but we don’t get the directory left behind:

>>> os.path.exists('foo')
False


It’s critical that recipes clean up partial effects when errors occur. Because recipes most commonly create files and directories, buildout provides a helper API for removing created files when an error occurs. Option objects have a created method that can be called to record files as they are created. If the install or update method returns with an error, then any registered paths are removed automatically. The method returns the files registered and can be used to return the files created. Let’s use this API to simplify the recipe:

>>> write(sample_buildout, 'recipes', 'mkdir.py',
... """
... import logging, os, zc.buildout
...
... class Mkdir:
...
...     def __init__(self, buildout, name, options):
...         self.name, self.options = name, options
...
...         # Normalize paths and check that their parent
...         # directories exist:
...         paths = []
...         for path in options['path'].split():
...             path = os.path.join(buildout['buildout']['directory'], path)
...             if not os.path.isdir(os.path.dirname(path)):
...                 logging.getLogger(self.name).error(
...                     'Cannot create %s. %s is not a directory.',
...                     options['path'], os.path.dirname(options['path']))
...                 raise zc.buildout.UserError('Invalid Path')
...             paths.append(path)
...         options['path'] = ' '.join(paths)
...
...     def install(self):
...         paths = self.options['path'].split()
...         for path in paths:
...             logging.getLogger(self.name).info(
...                 'Creating directory %s', os.path.basename(path))
...             os.mkdir(path)
...             self.options.created(path)
...
...         return self.options.created()
...
...     def update(self):
...         pass
... """)

>>> clean_up_pyc(sample_buildout, 'recipes', 'mkdir.py')


We returned by calling created, taking advantage of the fact that it returns the registered paths. We did this for illustrative purposes. It would be simpler just to return the paths as before.

If we rerun the buildout, again, we’ll get the error and no directories will be created:

>>> print_(system(buildout)) # doctest: +ELLIPSIS
Develop: '/sample-buildout/recipes'
Installing data-dir.
data-dir: Creating directory foo
data-dir: Creating directory bin
While:
Installing data-dir.
<BLANKLINE>
An internal error occured due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
... exists...

>>> os.path.exists('foo')
False


Now, we’ll fix the typo again and we’ll get the directories we expect:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir
...
... [data-dir]
... recipe = recipes:mkdir
... path = foo bins
... """)

>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
Installing data-dir.
data-dir: Creating directory foo
data-dir: Creating directory bins

>>> os.path.exists('foo')
True
>>> os.path.exists('bins')
True


#### Configuration file syntax

A buildout configuration file consists of a sequence of sections. A section has a section header followed by 0 or more section options. (Buildout configuration files may be viewed as a variation on INI files.)

A section header consists of a section name enclosed in square braces. A section name consists of one or more non-whitespace characters other than square braces (‘[’, ‘]’), curly braces (‘{’, ‘}’), colons (‘:’) or equal signs (‘=’). Whitespace surrounding section names is ignored.

Options consist of option names, followed by optional space or tab characters, an optional plus or minus sign and an equal signs and values. An option value may be spread over multiple lines as long as the lines after the first start with a whitespace character. An option name consists of one or more non-whitespace characters other than equal signs, square braces (“[”, “]”), curly braces (“{”, “}”), plus signs or colons (“:”). The option name ‘<’ is reserved. An option’s data consists of the characters following the equal sign on the start line, plus the continuation lines.

Option values have extra whitespace stripped. How this is done depends on whether the value has non-whitespace characterts on the first line. If an option value has non-whitespace characters on the first line, then each line is stripped and blank lines are removed. For exampe, in:

[foo]
bar = 1
baz = a
b

c


The value of of bar is '1' and the value of baz is 'a\nb\nc'.

If the first line of an option doesn’t contain whitespace, then the value is dedented (with textwrap.dedent), trailing spaces in lines are removed, and leading and trailing blank lines are removed. For example, in:

[foo]
bar =
baz =

a
b

c


The value of bar is '', and the value of baz is 'a\n  b\n\nc'.

Lines starting with ‘#’ or ‘;’ characters are comments. Comments can also be placed after the closing square bracket (‘]’) in a section header.

Buildout configuration data are Python strings, which are bytes in Python 2 and unicode in Python 3.

Sections and options within sections may be repeated. Multiple occurrences of of a section are treated as if they were concantinated. The last option value for a given name in a section overrides previous values.

In addition top the syntactic details above:

• option names are case sensitive
• option values can use a substitution syntax, described below, to refer to option values in specific sections.
• option values can be appended or removed using the - and + operators.

#### Annotated sections

When used with the annotate command, buildout displays annotated sections. All sections are displayed, sorted alphabetically. For each section, all key-value pairs are displayed, sorted alphabetically, along with the origin of the value (file name or COMPUTED_VALUE, DEFAULT_VALUE, COMMAND_LINE_VALUE).

>>> print_(system(buildout+ ' annotate'), end='')
... # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
<BLANKLINE>
Annotated sections
==================
<BLANKLINE>
[buildout]
allow-hosts= *
DEFAULT_VALUE
allow-picked-versions= true
DEFAULT_VALUE
bin-directory= bin
DEFAULT_VALUE
develop= recipes
/sample-buildout/buildout.cfg
develop-eggs-directory= develop-eggs
DEFAULT_VALUE
directory= /sample-buildout
COMPUTED_VALUE
eggs-directory= eggs
DEFAULT_VALUE
executable= ...
DEFAULT_VALUE
DEFAULT_VALUE
install-from-cache= false
DEFAULT_VALUE
installed= .installed.cfg
DEFAULT_VALUE
log-format=
DEFAULT_VALUE
log-level= INFO
DEFAULT_VALUE
DEFAULT_VALUE
offline= false
DEFAULT_VALUE
parts= data-dir
/sample-buildout/buildout.cfg
parts-directory= parts
DEFAULT_VALUE
prefer-final= true
DEFAULT_VALUE
python= buildout
DEFAULT_VALUE
socket-timeout=
DEFAULT_VALUE
DEFAULT_VALUE
<BLANKLINE>
[data-dir]
path= foo bins
/sample-buildout/buildout.cfg
recipe= recipes:mkdir
/sample-buildout/buildout.cfg
<BLANKLINE>


#### Variable substitutions

Buildout configuration files support variable substitution. To illustrate this, we’ll create an debug recipe to allow us to see interactions with the buildout:

>>> write(sample_buildout, 'recipes', 'debug.py',
... """
... import sys
... class Debug:
...
...     def __init__(self, buildout, name, options):
...         self.buildout = buildout
...         self.name = name
...         self.options = options
...
...     def install(self):
...         for option, value in sorted(self.options.items()):
...             sys.stdout.write('%s %s\\n' % (option, value))
...         return ()
...
...     update = install
... """)


This recipe doesn’t actually create anything. The install method doesn’t return anything, because it didn’t create any files or directories.

We also have to update our setup script:

>>> write(sample_buildout, 'recipes', 'setup.py',
... """
... from setuptools import setup
... entry_points = (
... '''
... [zc.buildout]
... mkdir = mkdir:Mkdir
... debug = debug:Debug
... ''')
... setup(name="recipes", entry_points=entry_points)
... """)


We’ve rearranged the script a bit to make the entry points easier to edit. In particular, entry points are now defined as a configuration string, rather than a dictionary.

Let’s update our configuration to provide variable substitution examples:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir debug
... log-level = INFO
...
... [debug]
... recipe = recipes:debug
... File-1 = ${data-dir:path}/file ... File-2 =${debug:File-1}/log
...
... [data-dir]
... recipe = recipes:mkdir
... path = mydata
... """)


We used a string-template substitution for File-1 and File-2. This type of substitution uses the string.Template syntax. Names substituted are qualified option names, consisting of a section name and option name joined by a colon.

Now, if we run the buildout, we’ll see the options with the values substituted.

>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
Uninstalling data-dir.
Installing data-dir.
data-dir: Creating directory mydata
Installing debug.
File-1 /sample-buildout/mydata/file
File-2 /sample-buildout/mydata/file/log
recipe recipes:debug


Note that the substitution of the data-dir path option reflects the update to the option performed by the mkdir recipe.

It might seem surprising that mydata was created again. This is because we changed our recipes package by adding the debug module. The buildout system didn’t know if this module could effect the mkdir recipe, so it assumed it could and reinstalled mydata. If we rerun the buildout:

>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
Updating data-dir.
Updating debug.
File-1 /sample-buildout/mydata/file
File-2 /sample-buildout/mydata/file/log
recipe recipes:debug


We can see that mydata was not recreated.

Note that, in this case, we didn’t specify a log level, so we didn’t get output about what the buildout was doing.

Section and option names in variable substitutions are only allowed to contain alphanumeric characters, hyphens, periods and spaces. This restriction might be relaxed in future releases.

We can ommit the section name in a variable substitution to refer to the current section. We can also use the special option, _buildout_section_name_ to get the current section name.

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir debug
... log-level = INFO
...
... [debug]
... recipe = recipes:debug
... File-1 = ${data-dir:path}/file ... File-2 =${:File-1}/log
... my_name = ${:_buildout_section_name_} ... ... [data-dir] ... recipe = recipes:mkdir ... path = mydata ... """)  >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Updating data-dir. Installing debug. File-1 /sample-buildout/mydata/file File-2 /sample-buildout/mydata/file/log my_name debug recipe recipes:debug  #### Automatic part selection and ordering When a section with a recipe is referred to, either through variable substitution or by an initializing recipe, the section is treated as a part and added to the part list before the referencing part. For example, we can leave data-dir out of the parts list: >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug ... log-level = INFO ... ... [debug] ... recipe = recipes:debug ... File-1 =${data-dir:path}/file
... File-2 = ${debug:File-1}/log ... ... [data-dir] ... recipe = recipes:mkdir ... path = mydata ... """)  It will still be treated as a part: >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Updating data-dir. Installing debug. File-1 /sample-buildout/mydata/file File-2 /sample-buildout/mydata/file/log recipe recipes:debug  >>> cat('.installed.cfg') # doctest: +ELLIPSIS [buildout] installed_develop_eggs = /sample-buildout/develop-eggs/recipes.egg-link parts = data-dir debug ...  Note that the data-dir part is included before the debug part, because the debug part refers to the data-dir part. Even if we list the data-dir part after the debug part, it will be included before: >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug data-dir ... log-level = INFO ... ... [debug] ... recipe = recipes:debug ... File-1 =${data-dir:path}/file
... color = red
...
... [with_file2]
... <= debug
... file2 = ${:path}/file2 ... color = blue ... ... [myfiles] ... <= with_file1 ... with_file2 ... path = mydata ... """)  >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Uninstalling data-dir. Installing myfiles. color blue file1 mydata/file1 file2 mydata/file2 path mydata recipe recipes:debug  In this example, the debug, with_file1 and with_file2 sections act as macros. In particular, the variable substitutions are performed relative to the myfiles section. #### Adding and removing options We can append and remove values to an option by using the + and - operators. This is illustrated below; first we define a base configuration. >>> write(sample_buildout, 'base.cfg', ... """ ... [buildout] ... parts = part1 part2 part3 ... ... [part1] ... recipe = ... option = a1 a2 ... ... [part2] ... recipe = ... option = b1 b2 b3 b4 ... ... [part3] ... recipe = ... option = c1 c2 ... ... """)  Extending this configuration, we can “adjust” the values set in the base configuration file. >>> write(sample_buildout, 'extension1.cfg', ... """ ... [buildout] ... extends = base.cfg ... ... # appending values ... [part1] ... option += a3 a4 ... ... # removing values ... [part2] ... option -= b1 b2 ... ... # alt. spelling ... [part3] ... option+=c3 c4 c5 ... ... # normal assignment ... [part4] ... option = h1 h2 ... ... """)  An additional extension. >>> write(sample_buildout, 'extension2.cfg', ... """ ... [buildout] ... extends = extension1.cfg ... ... # appending values ... [part1] ... option += a5 ... ... # removing values ... [part2] ... option -= b1 b2 b3 ... ... """)  To verify that the options are adjusted correctly, we’ll set up an extension that prints out the options. >>> mkdir(sample_buildout, 'demo') >>> write(sample_buildout, 'demo', 'demo.py', ... """ ... import sys ... def ext(buildout): ... sys.stdout.write(str( ... [part['option'] for name, part in sorted(buildout.items()) ... if name.startswith('part')])+'\\n') ... """)  >>> write(sample_buildout, 'demo', 'setup.py', ... """ ... from setuptools import setup ... ... setup( ... name="demo", ... entry_points={'zc.buildout.extension': ['ext = demo:ext']}, ... ) ... """)  Set up a buildout configuration for this extension. >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = demo ... parts = ... """)  >>> os.chdir(sample_buildout) >>> print_(system(os.path.join(sample_buildout, 'bin', 'buildout')), end='') ... # doctest: +ELLIPSIS Develop: '/sample-buildout/demo'...  Verify option values. >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = demo ... extensions = demo ... extends = extension2.cfg ... """)  >>> print_(system(os.path.join('bin', 'buildout')), end='') ['a1 a2/na3 a4/na5', 'b1 b2 b3 b4', 'c1 c2/nc3 c4 c5', 'h1 h2'] Develop: '/sample-buildout/demo'  Annotated sections output shows which files are responsible for which operations. >>> print_(system(os.path.join('bin', 'buildout') + ' annotate'), end='') ... # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE <BLANKLINE> Annotated sections ================== ... <BLANKLINE> [part1] option= a1 a2 a3 a4 a5 /sample-buildout/base.cfg += /sample-buildout/extension1.cfg += /sample-buildout/extension2.cfg recipe= /sample-buildout/base.cfg <BLANKLINE> [part2] option= b1 b2 b3 b4 /sample-buildout/base.cfg -= /sample-buildout/extension1.cfg -= /sample-buildout/extension2.cfg recipe= /sample-buildout/base.cfg <BLANKLINE> [part3] option= c1 c2 c3 c4 c5 /sample-buildout/base.cfg += /sample-buildout/extension1.cfg recipe= /sample-buildout/base.cfg <BLANKLINE> [part4] option= h1 h2 /sample-buildout/extension1.cfg  Cleanup. >>> os.remove(os.path.join(sample_buildout, 'base.cfg')) >>> os.remove(os.path.join(sample_buildout, 'extension1.cfg')) >>> os.remove(os.path.join(sample_buildout, 'extension2.cfg'))  #### Multiple configuration files A configuration file can “extend” another configuration file. Options are read from the other configuration file if they aren’t already defined by your configuration file. The configuration files your file extends can extend other configuration files. The same file may be used more than once although, of course, cycles aren’t allowed. To see how this works, we use an example: >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... extends = base.cfg ... ... [debug] ... op = buildout ... """)  >>> write(sample_buildout, 'base.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug ... ... [debug] ... recipe = recipes:debug ... op = base ... """)  >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Installing debug. op buildout recipe recipes:debug  The example is pretty trivial, but the pattern it illustrates is pretty common. In a more practical example, the base buildout might represent a product and the extending buildout might be a customization. Here is a more elaborate example. >>> other = tmpdir('other')  >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... extends = b1.cfg b2.cfg %(b3)s ... ... [debug] ... op = buildout ... """ % dict(b3=os.path.join(other, 'b3.cfg')))  >>> write(sample_buildout, 'b1.cfg', ... """ ... [buildout] ... extends = base.cfg ... ... [debug] ... op1 = b1 1 ... op2 = b1 2 ... """)  >>> write(sample_buildout, 'b2.cfg', ... """ ... [buildout] ... extends = base.cfg ... ... [debug] ... op2 = b2 2 ... op3 = b2 3 ... """)  >>> write(other, 'b3.cfg', ... """ ... [buildout] ... extends = b3base.cfg ... ... [debug] ... op4 = b3 4 ... """)  >>> write(other, 'b3base.cfg', ... """ ... [debug] ... op5 = b3base 5 ... """)  >>> write(sample_buildout, 'base.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug ... ... [debug] ... recipe = recipes:debug ... name = base ... """)  >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Installing debug. name base op buildout op1 b1 1 op2 b2 2 op3 b2 3 op4 b3 4 op5 b3base 5 recipe recipes:debug  There are several things to note about this example: • We can name multiple files in an extends option. • We can reference files recursively. • Relative file names in extended options are interpreted relative to the directory containing the referencing configuration file. #### Loading Configuration from URLs Configuration files can be loaded from URLs. To see how this works, we’ll set up a web server with some configuration files. >>> server_data = tmpdir('server_data')  >>> write(server_data, "r1.cfg", ... """ ... [debug] ... op1 = r1 1 ... op2 = r1 2 ... """)  >>> write(server_data, "r2.cfg", ... """ ... [buildout] ... extends = r1.cfg ... ... [debug] ... op2 = r2 2 ... op3 = r2 3 ... """)  >>> server_url = start_server(server_data)  >>> write('client.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug ... extends = %(url)s/r2.cfg ... ... [debug] ... recipe = recipes:debug ... name = base ... """ % dict(url=server_url))  >>> print_(system(buildout+ ' -c client.cfg'), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Installing debug. name base op1 r1 1 op2 r2 2 op3 r2 3 recipe recipes:debug  Here we specified a URL for the file we extended. The file we downloaded, itself referred to a file on the server using a relative URL reference. Relative references are interpreted relative to the base URL when they appear in configuration files loaded via URL. We can also specify a URL as the configuration file to be used by a buildout. >>> os.remove('client.cfg') >>> write(server_data, 'remote.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug ... extends = r2.cfg ... ... [debug] ... recipe = recipes:debug ... name = remote ... """)  >>> print_(system(buildout + ' -c ' + server_url + '/remote.cfg'), end='') While: Initializing. Error: Missing option: buildout:directory  Normally, the buildout directory defaults to directory containing a configuration file. This won’t work for configuration files loaded from URLs. In this case, the buildout directory would normally be defined on the command line: >>> print_(system(buildout ... + ' -c ' + server_url + '/remote.cfg' ... + ' buildout:directory=' + sample_buildout ... ), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Installing debug. name remote op1 r1 1 op2 r2 2 op3 r2 3 recipe recipes:debug  #### User defaults If the file$HOME/.buildout/default.cfg, exists, it is read before reading the configuration file. ($HOME is the value of the HOME environment variable. The ‘/’ is replaced by the operating system file delimiter.) >>> old_home = os.environ['HOME'] >>> home = tmpdir('home') >>> mkdir(home, '.buildout') >>> write(home, '.buildout', 'default.cfg', ... """ ... [debug] ... op1 = 1 ... op7 = 7 ... """)  >>> os.environ['HOME'] = home >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Installing debug. name base op buildout op1 b1 1 op2 b2 2 op3 b2 3 op4 b3 4 op5 b3base 5 op7 7 recipe recipes:debug  A buildout command-line argument, -U, can be used to suppress reading user defaults: >>> print_(system(buildout + ' -U'), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Installing debug. name base op buildout op1 b1 1 op2 b2 2 op3 b2 3 op4 b3 4 op5 b3base 5 recipe recipes:debug  >>> os.environ['HOME'] = old_home  #### Log level We can control the level of logging by specifying a log level in out configuration file. For example, so suppress info messages, we can set the logging level to WARNING >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... log-level = WARNING ... extends = b1.cfg b2.cfg ... """)  >>> print_(system(buildout), end='') name base op1 b1 1 op2 b2 2 op3 b2 3 recipe recipes:debug  #### Socket timeout The timeout of the connections to egg and configuration servers can be configured in the buildout section. Its value is configured in seconds. >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... socket-timeout = 5 ... develop = recipes ... parts = debug ... ... [debug] ... recipe = recipes:debug ... op = timeout ... """)  >>> print_(system(buildout), end='') Setting socket time out to 5 seconds. Develop: '/sample-buildout/recipes' Uninstalling debug. Installing debug. op timeout recipe recipes:debug  If the socket-timeout is not numeric, a warning is issued and the default timeout of the Python socket module is used. >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... socket-timeout = 5s ... develop = recipes ... parts = debug ... ... [debug] ... recipe = recipes:debug ... op = timeout ... """)  >>> print_(system(buildout), end='') Default socket timeout is used ! Value in configuration is not numeric: [5s]. <BLANKLINE> Develop: '/sample-buildout/recipes' Updating debug. op timeout recipe recipes:debug  #### Uninstall recipes As we’ve seen, when parts are installed, buildout keeps track of files and directories that they create. When the parts are uninstalled these files and directories are deleted. Sometimes more clean up is needed. For example, a recipe might add a system service by calling chkconfig –add during installation. Later during uninstallation, chkconfig –del will need to be called to remove the system service. In order to deal with these uninstallation issues, you can register uninstall recipes. Uninstall recipes are registered using the ‘zc.buildout.uninstall’ entry point. Parts specify uninstall recipes using the ‘uninstall’ option. In comparison to regular recipes, uninstall recipes are much simpler. They are simply callable objects that accept the name of the part to be uninstalled and the part’s options dictionary. Uninstall recipes don’t have access to the part itself since it maybe not be able to be instantiated at uninstallation time. Here’s a recipe that simulates installation of a system service, along with an uninstall recipe that simulates removing the service. >>> write(sample_buildout, 'recipes', 'service.py', ... """ ... import sys ... class Service: ... ... def __init__(self, buildout, name, options): ... self.buildout = buildout ... self.name = name ... self.options = options ... ... def install(self): ... sys.stdout.write("chkconfig --add %s\\n" ... % self.options['script']) ... return () ... ... def update(self): ... pass ... ... ... def uninstall_service(name, options): ... sys.stdout.write("chkconfig --del %s\\n" % options['script']) ... """)  To use these recipes we must register them using entry points. Make sure to use the same name for the recipe and uninstall recipe. This is required to let buildout know which uninstall recipe goes with which recipe. >>> write(sample_buildout, 'recipes', 'setup.py', ... """ ... from setuptools import setup ... entry_points = ( ... ''' ... [zc.buildout] ... mkdir = mkdir:Mkdir ... debug = debug:Debug ... service = service:Service ... ... [zc.buildout.uninstall] ... service = service:uninstall_service ... ''') ... setup(name="recipes", entry_points=entry_points) ... """)  Here’s how these recipes could be used in a buildout: >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = service ... ... [service] ... recipe = recipes:service ... script = /path/to/script ... """)  When the buildout is run the service will be installed >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Installing service. chkconfig --add /path/to/script  The service has been installed. If the buildout is run again with no changes, the service shouldn’t be changed. >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Updating service.  Now we change the service part to trigger uninstallation and re-installation. >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = service ... ... [service] ... recipe = recipes:service ... script = /path/to/a/different/script ... """)  >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling service. Running uninstall recipe. chkconfig --del /path/to/script Installing service. chkconfig --add /path/to/a/different/script  Now we remove the service part, and add another part. >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug ... ... [debug] ... recipe = recipes:debug ... """)  >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling service. Running uninstall recipe. chkconfig --del /path/to/a/different/script Installing debug. recipe recipes:debug  Uninstall recipes don’t have to take care of removing all the files and directories created by the part. This is still done automatically, following the execution of the uninstall recipe. An upshot is that an uninstallation recipe can access files and directories created by a recipe before they are deleted. For example, here’s an uninstallation recipe that simulates backing up a directory before it is deleted. It is designed to work with the mkdir recipe introduced earlier. >>> write(sample_buildout, 'recipes', 'backup.py', ... """ ... import os, sys ... def backup_directory(name, options): ... path = options['path'] ... size = len(os.listdir(path)) ... sys.stdout.write("backing up directory %s of size %s\\n" ... % (path, size)) ... """)  It must be registered with the zc.buildout.uninstall entry point. Notice how it is given the name ‘mkdir’ to associate it with the mkdir recipe. >>> write(sample_buildout, 'recipes', 'setup.py', ... """ ... from setuptools import setup ... entry_points = ( ... ''' ... [zc.buildout] ... mkdir = mkdir:Mkdir ... debug = debug:Debug ... service = service:Service ... ... [zc.buildout.uninstall] ... uninstall_service = service:uninstall_service ... mkdir = backup:backup_directory ... ''') ... setup(name="recipes", entry_points=entry_points) ... """)  Now we can use it with a mkdir part. >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = dir debug ... ... [dir] ... recipe = recipes:mkdir ... path = my_directory ... ... [debug] ... recipe = recipes:debug ... """)  Run the buildout to install the part. >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Installing dir. dir: Creating directory my_directory Installing debug. recipe recipes:debug  Now we remove the part from the configuration file. >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug ... ... [debug] ... recipe = recipes:debug ... """)  When the buildout is run the part is removed, and the uninstall recipe is run before the directory is deleted. >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling dir. Running uninstall recipe. backing up directory /sample-buildout/my_directory of size 0 Updating debug. recipe recipes:debug  Now we will return the registration to normal for the benefit of the rest of the examples. >>> write(sample_buildout, 'recipes', 'setup.py', ... """ ... from setuptools import setup ... entry_points = ( ... ''' ... [zc.buildout] ... mkdir = mkdir:Mkdir ... debug = debug:Debug ... ''') ... setup(name="recipes", entry_points=entry_points) ... """)  #### Command-line usage A number of arguments can be given on the buildout command line. The command usage is: buildout [options and assignments] [command [command arguments]]  The following options are supported: -h (or –help) Print basic usage information. If this option is used, then all other options are ignored.  -c filename The -c option can be used to specify a configuration file, rather than buildout.cfg in the current directory. -t socket_timeout Specify the socket timeout in seconds. -v Increment the verbosity by 10. The verbosity is used to adjust the logging level. The verbosity is subtracted from the numeric value of the log-level option specified in the configuration file. -q Decrement the verbosity by 10. -U Don’t read user-default configuration. -o Run in off-line mode. This is equivalent to the assignment buildout:offline=true. -O Run in non-off-line mode. This is equivalent to the assignment buildout:offline=false. This is the default buildout mode. The -O option would normally be used to override a true offline setting in a configuration file. -n Run in newest mode. This is equivalent to the assignment buildout:newest=true. With this setting, which is the default, buildout will try to find the newest versions of distributions available that satisfy its requirements. -N Run in non-newest mode. This is equivalent to the assignment buildout:newest=false. With this setting, buildout will not seek new distributions if installed distributions satisfy it’s requirements. Assignments are of the form: section_name:option_name=value  Options and assignments can be given in any order. Here’s an example: >>> write(sample_buildout, 'other.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug ... installed = .other.cfg ... log-level = WARNING ... ... [debug] ... name = other ... recipe = recipes:debug ... """)  Note that we used the installed buildout option to specify an alternate file to store information about installed parts. >>> print_(system(buildout+' -c other.cfg debug:op1=foo -v'), end='') Develop: '/sample-buildout/recipes' Installing debug. name other op1 foo recipe recipes:debug  Here we used the -c option to specify an alternate configuration file, and the -v option to increase the level of logging from the default, WARNING. Options can also be combined in the usual Unix way, as in: >>> print_(system(buildout+' -vcother.cfg debug:op1=foo'), end='') Develop: '/sample-buildout/recipes' Updating debug. name other op1 foo recipe recipes:debug  Here we combined the -v and -c options with the configuration file name. Note that the -c option has to be last, because it takes an argument. >>> os.remove(os.path.join(sample_buildout, 'other.cfg')) >>> os.remove(os.path.join(sample_buildout, '.other.cfg'))  The most commonly used command is ‘install’ and it takes a list of parts to install. if any parts are specified, only those parts are installed. To illustrate this, we’ll update our configuration and run the buildout in the usual way: >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug d1 d2 d3 ... ... [d1] ... recipe = recipes:mkdir ... path = d1 ... ... [d2] ... recipe = recipes:mkdir ... path = d2 ... ... [d3] ... recipe = recipes:mkdir ... path = d3 ... ... [debug] ... recipe = recipes:debug ... """)  >>> print_(system(buildout), end='') Develop: '/sample-buildout/recipes' Uninstalling debug. Installing debug. recipe recipes:debug Installing d1. d1: Creating directory d1 Installing d2. d2: Creating directory d2 Installing d3. d3: Creating directory d3  >>> ls(sample_buildout) - .installed.cfg - b1.cfg - b2.cfg - base.cfg d bin - buildout.cfg d d1 d d2 d d3 d demo d develop-eggs d eggs d parts d recipes  >>> cat(sample_buildout, '.installed.cfg') ... # doctest: +NORMALIZE_WHITESPACE [buildout] installed_develop_eggs = /sample-buildout/develop-eggs/recipes.egg-link parts = debug d1 d2 d3 <BLANKLINE> [debug] __buildout_installed__ = __buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg== recipe = recipes:debug <BLANKLINE> [d1] __buildout_installed__ = /sample-buildout/d1 __buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg== path = /sample-buildout/d1 recipe = recipes:mkdir <BLANKLINE> [d2] __buildout_installed__ = /sample-buildout/d2 __buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg== path = /sample-buildout/d2 recipe = recipes:mkdir <BLANKLINE> [d3] __buildout_installed__ = /sample-buildout/d3 __buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg== path = /sample-buildout/d3 recipe = recipes:mkdir  Now we’ll update our configuration file: >>> write(sample_buildout, 'buildout.cfg', ... """ ... [buildout] ... develop = recipes ... parts = debug d2 d3 d4 ... ... [d2] ... recipe = recipes:mkdir ... path = data2 ... ... [d3] ... recipe = recipes:mkdir ... path = data3 ... ... [d4] ... recipe = recipes:mkdir ... path =${d2:path}-extra
...
... [debug]
... recipe = recipes:debug
... x = 1
... """)


and run the buildout specifying just d3 and d4:

>>> print_(system(buildout+' install d3 d4'), end='')
Develop: '/sample-buildout/recipes'
Uninstalling d3.
Installing d3.
d3: Creating directory data3
Installing d4.
d4: Creating directory data2-extra

>>> ls(sample_buildout)
-  .installed.cfg
-  b1.cfg
-  b2.cfg
-  base.cfg
d  bin
-  buildout.cfg
d  d1
d  d2
d  data2-extra
d  data3
d  demo
d  develop-eggs
d  eggs
d  parts
d  recipes


Only the d3 and d4 recipes ran. d3 was removed and data3 and data2-extra were created.

The .installed.cfg is only updated for the recipes that ran:

>>> cat(sample_buildout, '.installed.cfg')
... # doctest: +NORMALIZE_WHITESPACE
[buildout]
parts = debug d1 d2 d3 d4
<BLANKLINE>
[debug]
__buildout_installed__ =
__buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg==
recipe = recipes:debug
<BLANKLINE>
[d1]
__buildout_installed__ = /sample-buildout/d1
__buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg==
path = /sample-buildout/d1
recipe = recipes:mkdir
<BLANKLINE>
[d2]
__buildout_installed__ = /sample-buildout/d2
__buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg==
path = /sample-buildout/d2
recipe = recipes:mkdir
<BLANKLINE>
[d3]
__buildout_installed__ = /sample-buildout/data3
__buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg==
path = /sample-buildout/data3
recipe = recipes:mkdir
<BLANKLINE>
[d4]
__buildout_installed__ = /sample-buildout/data2-extra
__buildout_signature__ = recipes-PiIFiO8ny5yNZ1S3JfT0xg==
path = /sample-buildout/data2-extra
recipe = recipes:mkdir


Note that the installed data for debug, d1, and d2 haven’t changed, because we didn’t install those parts and that the d1 and d2 directories are still there.

Now, if we run the buildout without the install command:

>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
Uninstalling d2.
Uninstalling d1.
Uninstalling debug.
Installing debug.
recipe recipes:debug
x 1
Installing d2.
d2: Creating directory data2
Updating d3.
Updating d4.


We see the output of the debug recipe and that data2 was created. We also see that d1 and d2 have gone away:

>>> ls(sample_buildout)
-  .installed.cfg
-  b1.cfg
-  b2.cfg
-  base.cfg
d  bin
-  buildout.cfg
d  data2
d  data2-extra
d  data3
d  demo
d  develop-eggs
d  eggs
d  parts
d  recipes


#### Alternate directory and file locations

The buildout normally puts the bin, eggs, and parts directories in the directory in the directory containing the configuration file. You can provide alternate locations, and even names for these directories.

>>> alt = tmpdir('sample-alt')

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts =
... bin-directory = %(scripts)s
... parts-directory = %(work)s
... """ % dict(
...    scripts = os.path.join(alt, 'scripts'),
...    work = os.path.join(alt, 'work'),
... ))

>>> print_(system(buildout), end='')
Creating directory '/sample-alt/scripts'.
Creating directory '/sample-alt/work'.
Develop: '/sample-buildout/recipes'
Uninstalling d4.
Uninstalling d3.
Uninstalling d2.
Uninstalling debug.

>>> ls(alt)
d  scripts
d  work

>>> ls(alt, 'developbasket')


You can also specify an alternate buildout directory:

>>> rmdir(alt)
>>> alt = tmpdir('sample-alt')

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... directory = %(alt)s
... develop = %(recipes)s
... parts =
... """ % dict(
...    alt=alt,
...    recipes=os.path.join(sample_buildout, 'recipes'),
...    ))

>>> print_(system(buildout), end='')
Creating directory '/sample-alt/bin'.
Creating directory '/sample-alt/parts'.
Creating directory '/sample-alt/eggs'.
Creating directory '/sample-alt/develop-eggs'.
Develop: '/sample-buildout/recipes'

>>> ls(alt)
-  .installed.cfg
d  bin
d  develop-eggs
d  eggs
d  parts

>>> ls(alt, 'develop-eggs')


#### Logging control

Three buildout options are used to control logging:

log-level
specifies the log level
verbosity
log-format
allows an alternate logging for mat to be specified

We’ve already seen the log level and verbosity. Let’s look at an example of changing the format:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts =
... log-level = 25
... verbosity = 5
... log-format = %(levelname)s %(message)s
... """)


Here, we’ve changed the format to include the log-level name, rather than the logger name.

We’ve also illustrated, with a contrived example, that the log level can be a numeric value and that the verbosity can be specified in the configuration file. Because the verbosity is subtracted from the log level, we get a final log level of 20, which is the INFO level.

>>> print_(system(buildout), end='')
INFO Develop: '/sample-buildout/recipes'


#### Predefined buildout options

Buildouts have a number of predefined options that recipes can use and that users can override in their configuration files. To see these, we’ll run a minimal buildout configuration with a debug logging level. One of the features of debug logging is that the configuration database is shown.

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... parts =
... """)

>>> print_(system(buildout+' -vv'), end='') # doctest: +NORMALIZE_WHITESPACE
Installing 'zc.buildout >=1.9a1', 'distribute'.
We have a develop egg: zc.buildout 1.0.0.
We have the best distribution that satisfies 'distribute'.
Picked: distribute = 0.6
<BLANKLINE>
Configuration data:
[buildout]
allow-hosts = *
allow-picked-versions = true
bin-directory = /sample-buildout/bin
develop-eggs-directory = /sample-buildout/develop-eggs
directory = /sample-buildout
eggs-directory = /sample-buildout/eggs
executable = python
install-from-cache = false
installed = /sample-buildout/.installed.cfg
log-format =
log-level = INFO
offline = false
parts =
parts-directory = /sample-buildout/parts
prefer-final = true
python = buildout
socket-timeout =
verbosity = 20
zc.buildout-version = >=1.9a1
<BLANKLINE>


All of these options can be overridden by configuration files or by command-line assignments. We’ve discussed most of these options already, but let’s review them and touch on some we haven’t discussed:

allow-hosts

On some environments the links visited by zc.buildout can be forbidden by paranoid firewalls. These URLs might be in the chain of links visited by zc.buildout as defined by buildout’s find-links option, or as defined by various eggs in their url, download_url, dependency_links metadata.

The fact that package_index works like a spider and might visit links and go to other locations makes this even harder.

The allow-hosts option provides a way to prevent this, and works exactly like the one provided in easy_install.

You can provide a list of allowed host, together with wildcards:

[buildout]
...

allow-hosts =
*.python.org
example.com


All URLs that does not match these hosts will not be visited.

allow-picked-versions
By default, the buildout will choose the best match for a given requirement if the requirement is not specified precisely (for instance, using the “versions” option. This behavior corresponds to the “allow-picked-versions” being set to its default value, “true”. If “allow-picked-versions” is “false,” instead of picking the best match, buildout will raise an error. This helps enforce repeatability.
bin-directory
The directory path where scripts are written. This can be a relative path, which is interpreted relative to the directory option.
develop-eggs-directory
The directory path where development egg links are created for software being created in the local project. This can be a relative path, which is interpreted relative to the directory option.
directory
The buildout directory. This is the base for other buildout file and directory locations, when relative locations are used.
eggs-directory
The directory path where downloaded eggs are put. It is common to share this directory across buildouts. Eggs in this directory should never be modified. This can be a relative path, which is interpreted relative to the directory option.
executable
The Python executable used to run the buildout. See the python option below.

You can specify more locations to search for distributions using the find-links option. All locations specified will be searched for distributions along with the package index as described before.

Locations can be urls:

[buildout]
...


They can also be directories on disk:

[buildout]
...


Finally, they can also be direct paths to distributions:

[buildout]
...


Any number of locations can be specified in the find-links option:

[buildout]
...
/some/otherpath
/some/path/someegg-1.0.0-py2.3.egg

install-from-cache
A download cache can be used as the basis of application source releases. In an application source release, we want to distribute an application that can be built without making any network accesses. In this case, we distribute a buildout with download cache and tell the buildout to install from the download cache only, without making network accesses. The buildout install-from-cache option can be used to signal that packages should be installed only from the download cache.
installed
The file path where information about the results of the previous buildout run is written. This can be a relative path, which is interpreted relative to the directory option. This file provides an inventory of installed parts with information needed to decide which if any parts need to be uninstalled.
log-format
The format used for logging messages.
log-level
The log level before verbosity adjustment
By default buildout and recipes will try to find the newest versions of distributions needed to satisfy requirements. This can be very time consuming, especially when incrementally working on setting up a buildout or working on a recipe. The buildout “newest” option can be used to to suppress this. If the “newest” option is set to false, then new distributions won’t be sought if an installed distribution meets requirements. The “newest” option can also be set to false using the -N command-line option. See also the “offline” option.
offline
The “offline” option goes a bit further than the “newest” option. If the buildout “offline” option is given a value of “true”, the buildout and recipes that are aware of the option will avoid doing network access. This is handy when running the buildout when not connected to the internet. It also makes buildouts run much faster. This option is typically set using the buildout -o option.
parts
A white space separated list of parts to be installed.
parts-directory
A working directory that parts can used to store data.
prefer-final

Currently, when searching for new releases, the newest available release is used. This isn’t usually ideal, as you may get a development release or alpha releases not ready to be widely used. You can request that final releases be preferred using the prefer final option in the buildout section:

[buildout]
...
prefer-final = true


When the prefer-final option is set to true, then when searching for new releases, final releases are preferred. If there are final releases that satisfy distribution requirements, then those releases are used even if newer non-final releases are available. The buildout prefer-final option can be used to override this behavior.

In buildout version 2, final releases will be preferred by default. You will then need to use a false value for prefer-final to get the newest releases.

python
The name of a section containing information about the default Python interpreter. Recipes that need a installation typically have options to tell them which Python installation to use. By convention, if a section-specific option isn’t used, the option is looked for in the buildout section. The option must point to a section with an executable option giving the path to a Python executable. By default, the buildout section defines the default Python as the Python used to run the buildout.

By default buildout will obey the setuptools dependency_links metadata when it looks for dependencies. This behavior can be controlled with the use-dependency-links buildout option:

[buildout]
...


The option defaults to true. If you set it to false, then dependency links are only looked for in the locations specified by find-links.

verbosity
A log-level adjustment. Typically, this is set via the -q and -v command-line options.

#### Creating new buildouts and bootstrapping

If zc.buildout is installed, you can use it to create a new buildout with it’s own local copies of zc.buildout and distribute and with local buildout scripts.

>>> sample_bootstrapped = tmpdir('sample-bootstrapped')

>>> print_(system(buildout
...              +' -c'+os.path.join(sample_bootstrapped, 'setup.cfg')
...              +' init'), end='')
Creating '/sample-bootstrapped/setup.cfg'.
Creating directory '/sample-bootstrapped/bin'.
Creating directory '/sample-bootstrapped/parts'.
Creating directory '/sample-bootstrapped/eggs'.
Creating directory '/sample-bootstrapped/develop-eggs'.
Generated script '/sample-bootstrapped/bin/buildout'.


Note that a basic setup.cfg was created for us. This is because we provided an ‘init’ argument. By default, the generated setup.cfg is as minimal as it could be:

>>> cat(sample_bootstrapped, 'setup.cfg')
[buildout]
parts =


We also get other buildout artifacts:

>>> ls(sample_bootstrapped)
d  bin
d  develop-eggs
d  eggs
d  parts
-  setup.cfg

>>> ls(sample_bootstrapped, 'bin')
-  buildout

>>> _ = (ls(sample_bootstrapped, 'eggs'),
...      ls(sample_bootstrapped, 'develop-eggs'))
-  distribute-0.6-py2.3.egg
-  zc.buildout-1.0-py2.3.egg


(We list both the eggs and develop-eggs directories because the buildout or distribute egg could be installed in the develop-eggs directory if the original buildout had develop eggs for either buildout or distribute.)

Note that the buildout script was installed but not run. To run the buildout, we’d have to run the installed buildout script.

If we have an existing buildout that already has a buildout.cfg, we’ll normally use the bootstrap command instead of init. It will complain if there isn’t a configuration file:

>>> sample_bootstrapped2 = tmpdir('sample-bootstrapped2')

>>> print_(system(buildout
...              +' -c'+os.path.join(sample_bootstrapped2, 'setup.cfg')
...              +' bootstrap'), end='')
While:
Initializing.
Error: Couldn't open /sample-bootstrapped2/setup.cfg

>>> write(sample_bootstrapped2, 'setup.cfg',
... """
... [buildout]
... parts =
... """)

>>> print_(system(buildout
...              +' -c'+os.path.join(sample_bootstrapped2, 'setup.cfg')
...              +' bootstrap'), end='')
Creating directory '/sample-bootstrapped2/bin'.
Creating directory '/sample-bootstrapped2/parts'.
Creating directory '/sample-bootstrapped2/eggs'.
Creating directory '/sample-bootstrapped2/develop-eggs'.
Generated script '/sample-bootstrapped2/bin/buildout'.


Similarly, if there is a configuration file and we use the init command, we’ll get an error that the configuration file already exists:

>>> print_(system(buildout
...              +' -c'+os.path.join(sample_bootstrapped, 'setup.cfg')
...              +' init'), end='')
While:
Initializing.


#### Initial eggs

When using the init command, you can specify distribution requirements or paths to use:

>>> cd(sample_bootstrapped)
>>> remove('setup.cfg')
>>> print_(system(buildout + ' -csetup.cfg init demo other ./src'), end='')
Creating '/sample-bootstrapped/setup.cfg'.
Getting distribution for 'zc.recipe.egg>=2.0.0a3'.
Got zc.recipe.egg
Installing py.
Getting distribution for 'demo'.
Got demo 0.3.
Getting distribution for 'other'.
Got other 1.0.
Getting distribution for 'demoneeded'.
Got demoneeded 1.1.
Generated script '/sample-bootstrapped/bin/demo'.
Generated script '/sample-bootstrapped/bin/distutilsscript'.
Generated interpreter '/sample-bootstrapped/bin/py'.


This causes a py part to be included that sets up a custom python interpreter with the given requirements or paths:

>>> cat('setup.cfg')
[buildout]
parts = py
<BLANKLINE>
[py]
recipe = zc.recipe.egg
interpreter = py
eggs =
demo
other
extra-paths =
./src


Passing requirements or paths causes the the builout to be run as part of initialization. In the example above, we got a number of distributions installed and 2 scripts generated. The first, demo, was defined by the demo project. The second, py was defined by the generated configuration. It’s a “custom interpreter” that behaves like a standard Python interpeter, except that includes the specified eggs and extra paths in it’s Python path.

We specified a source directory that didn’t exist. Buildout created it for us:

>>> ls('.')
-  .installed.cfg
d  bin
d  develop-eggs
d  eggs
d  parts
-  setup.cfg
d  src

>>> uncd()


#### Finding distributions

By default, buildout searches the Python Package Index when looking for distributions. You can, instead, specify your own index to search using the index option:

[buildout]
...
index = http://index.example.com/


This index, or the default of http://pypi.python.org/simple/ if no index is specified, will always be searched for distributions unless running buildout with options that prevent searching for distributions. The latest version of the distribution that meets the requirements of the buildout will always be used.

You can also specify more locations to search for distributions using the find-links option. See its description above.

#### Controlling the installation database

The buildout installed option is used to specify the file used to save information on installed parts. This option is initialized to “.installed.cfg”, but it can be overridden in the configuration file or on the command line:

>>> write('buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = debug
...
... [debug]
... recipe = recipes:debug
... """)

>>> print_(system(buildout+' buildout:installed=inst.cfg'), end='')
Develop: '/sample-buildout/recipes'
Installing debug.
recipe recipes:debug

>>> ls(sample_buildout)
-  b1.cfg
-  b2.cfg
-  base.cfg
d  bin
-  buildout.cfg
d  demo
d  develop-eggs
d  eggs
-  inst.cfg
d  parts
d  recipes


The installation database can be disabled by supplying an empty buildout installed option:

>>> os.remove('inst.cfg')
>>> print_(system(buildout+' buildout:installed='), end='')
Develop: '/sample-buildout/recipes'
Installing debug.
recipe recipes:debug

>>> ls(sample_buildout)
-  b1.cfg
-  b2.cfg
-  base.cfg
d  bin
-  buildout.cfg
d  demo
d  develop-eggs
d  eggs
d  parts
d  recipes


Note that there will be no installation database if there are no parts:

>>> write('buildout.cfg',
... """
... [buildout]
... parts =
... """)

>>> print_(system(buildout+' buildout:installed=inst.cfg'), end='')

>>> ls(sample_buildout)
-  b1.cfg
-  b2.cfg
-  base.cfg
d  bin
-  buildout.cfg
d  demo
d  develop-eggs
d  eggs
d  parts
d  recipes


#### Extensions

A feature allows code to be loaded and run after configuration files have been read but before the buildout has begun any processing. The intent is to allow special plugins such as urllib2 request handlers to be loaded.

To load an extension, we use the extensions option and list one or more distribution requirements, on separate lines. The distributions named will be loaded and any zc.buildout.extension entry points found will be called with the buildout as an argument. When buildout finishes processing, any zc.buildout.unloadextension entry points found will be called with the buildout as an argument.

Let’s create a sample extension in our sample buildout created in the previous section:

>>> mkdir(sample_bootstrapped, 'demo')

>>> write(sample_bootstrapped, 'demo', 'demo.py',
... """
... import sys
... def ext(buildout):
...     sys.stdout.write('%s %s\\n' % ('ext', list(buildout)))
...     sys.stdout.write('%s %s\\n' % ('unload', list(buildout)))
... """)

>>> write(sample_bootstrapped, 'demo', 'setup.py',
... """
... from setuptools import setup
...
... setup(
...     name = "demo",
...     entry_points = {
...        'zc.buildout.extension': ['ext = demo:ext'],
...        },
...     )
... """)


Our extension just prints out the word ‘demo’, and lists the sections found in the buildout passed to it.

We’ll update our buildout.cfg to list the demo directory as a develop egg to be built:

>>> write(sample_bootstrapped, 'buildout.cfg',
... """
... [buildout]
... develop = demo
... parts =
... """)

>>> os.chdir(sample_bootstrapped)
>>> print_(system(os.path.join(sample_bootstrapped, 'bin', 'buildout')),
...        end='')
Develop: '/sample-bootstrapped/demo'


Now we can add the extensions option. We were a bit tricky and ran the buildout once with the demo develop egg defined but without the extension option. This is because extensions are loaded before the buildout creates develop eggs. We needed to use a separate buildout run to create the develop egg. Normally, when eggs are loaded from the network, we wouldn’t need to do anything special.

>>> write(sample_bootstrapped, 'buildout.cfg',
... """
... [buildout]
... develop = demo
... extensions = demo
... parts =
... """)


We see that our extension is loaded and executed:

>>> print_(system(os.path.join(sample_bootstrapped, 'bin', 'buildout')),
...        end='')
ext ['buildout']
Develop: '/sample-bootstrapped/demo'


### Repeatable buildouts: controlling eggs used

One of the goals of zc.buildout is to provide enough control to make buildouts repeatable. It should be possible to check the buildout configuration files for a project into a version control system and later use the checked in files to get the same buildout, subject to changes in the environment outside the buildout.

An advantage of using Python eggs is that depenencies of eggs used are automatically determined and used. The automatic inclusion of depenent distributions is at odds with the goal of repeatable buildouts.

To support repeatable buildouts, a versions section can be created with options for each distribution name whos version is to be fixed. The section can then be specified via the buildout versions option.

To see how this works, we’ll create two versions of a recipe egg:

>>> mkdir('recipe')
>>> write('recipe', 'recipe.py',
... '''
... import sys
... print_ = lambda *a: sys.stdout.write(' '.join(map(str, a))+'\\n')
... class Recipe:
...     def __init__(*a): pass
...     def install(self):
...         print_('recipe v1')
...         return ()
...     update = install
... ''')

>>> write('recipe', 'setup.py',
... '''
... from setuptools import setup
... setup(name='spam', version='1', py_modules=['recipe'],
...       entry_points={'zc.buildout': ['default = recipe:Recipe']},
...       )
... ''')

>>> write('recipe', 'README', '')

>>> print_(system(buildout+' setup recipe bdist_egg')) # doctest: +ELLIPSIS
Running setup script 'recipe/setup.py'.
...

>>> rmdir('recipe', 'build')

>>> write('recipe', 'recipe.py',
... '''
... import sys
... print_ = lambda *a: sys.stdout.write(' '.join(map(str, a))+'\\n')
... class Recipe:
...     def __init__(*a): pass
...     def install(self):
...         print_('recipe v2')
...         return ()
...     update = install
... ''')

>>> write('recipe', 'setup.py',
... '''
... from setuptools import setup
... setup(name='spam', version='2', py_modules=['recipe'],
...       entry_points={'zc.buildout': ['default = recipe:Recipe']},
...       )
... ''')

>>> print_(system(buildout+' setup recipe bdist_egg')) # doctest: +ELLIPSIS
Running setup script 'recipe/setup.py'.
...


and we’ll configure a buildout to use it:

>>> write('buildout.cfg',
... '''
... [buildout]
... parts = foo
...
... [foo]
... recipe = spam
... ''' % join('recipe', 'dist'))


If we run the buildout, it will use version 2:

>>> print_(system(buildout), end='')
Getting distribution for 'spam'.
Got spam 2.
Installing foo.
recipe v2


We can specify a versions section that lists our recipe and name it in the buildout section:

>>> write('buildout.cfg',
... '''
... [buildout]
... parts = foo
... versions = release-1
...
... [release-1]
... spam = 1
... eggs = 2.2
...
... [foo]
... recipe = spam
... ''' % join('recipe', 'dist'))


Here we created a release-1 section listing the version 1 for the spam distribution. We told the buildout to use it by specifying release-1 as in the versions option.

Now, if we run the buildout, we’ll use version 1 of the spam recipe:

>>> print_(system(buildout), end='')
Getting distribution for 'spam==1'.
Got spam 1.
Uninstalling foo.
Installing foo.
recipe v1


Running the buildout in verbose mode will help us get information about versions used. If we run the buildout in verbose mode without specifying a versions section:

>>> print_(system(buildout+' buildout:versions= -v'), end='')
Installing 'zc.buildout >=1.99', 'distribute'.
We have a develop egg: zc.buildout 1.0.0.
We have the best distribution that satisfies 'distribute'.
Picked: distribute = 0.6
Installing 'spam'.
We have the best distribution that satisfies 'spam'.
Picked: spam = 2.
Uninstalling foo.
Installing foo.
recipe v2


We’ll get output that includes lines that tell us what versions buildout chose a for us, like:

zc.buildout.easy_install.picked: spam = 2


This allows us to discover versions that are picked dynamically, so that we can fix them in a versions section.

If we run the buildout with the versions section:

>>> print_(system(buildout+' -v'), end='')
Installing 'zc.buildout >=1.99', 'distribute'.
We have a develop egg: zc.buildout 1.0.0.
We have the best distribution that satisfies 'distribute'.
Picked: distribute = 0.6
Installing 'spam'.
We have the distribution that satisfies 'spam==1'.
Uninstalling foo.
Installing foo.
recipe v1


We won’t get output for the spam distribution, which we didn’t pick, but we will get output for distribute, which we didn’t specify versions for.

You can request buildout to generate an error if it picks any versions:

>>> write('buildout.cfg',
... '''
... [buildout]
... parts = foo
... versions = release-1
... allow-picked-versions = false
...
... [release-1]
... spam = 1
... eggs = 2.2
...
... [foo]
... recipe = spam
... ''' % join('recipe', 'dist'))


We setup an HTTP server that provides a file we want to download:

>>> server_data = tmpdir('sample_files')
>>> write(server_data, 'foo.txt', 'This is a foo text.')
>>> server_url = start_server(server_data)


We also use a fresh directory for temporary files in order to make sure that all temporary files have been cleaned up in the end:

>>> import tempfile
>>> old_tempdir = tempfile.tempdir
>>> tempfile.tempdir = tmpdir('tmp')


>>> from zc.buildout.download import Download
None


Downloading a file is achieved by calling the utility with the URL as an argument. A tuple is returned that consists of the path to the downloaded copy of the file and a boolean value indicating whether this is a temporary file meant to be cleaned up during the same buildout run:

>>> path, is_temp = download(server_url+'foo.txt')
>>> print_(path)
/.../buildout-...
>>> cat(path)
This is a foo text.


As we aren’t using the download cache and haven’t specified a target path either, the download has ended up in a temporary file:

>>> is_temp
True

>>> import tempfile
>>> path.startswith(tempfile.gettempdir())
True


We are responsible for cleaning up temporary files behind us:

>>> remove(path)


When trying to access a file that doesn’t exist, we’ll get an exception:

>>> try: download(server_url+'not-there') # doctest: +ELLIPSIS
... else: print_('woops')


>>> download(join(server_data, 'foo.txt'))
('/sample_files/foo.txt', False)


>>> try: from hashlib import md5
... except ImportError: from md5 import new as md5

>>> path, is_temp = download(server_url+'foo.txt',
...                          md5('This is a foo text.'.encode()).hexdigest())
>>> is_temp
True
>>> remove(path)

>>> download(server_url+'foo.txt',
...          md5('The wrong text.'.encode()).hexdigest())
Traceback (most recent call last):


The error message in the event of an MD5 checksum mismatch for a local file reads somewhat differently:

>>> download(join(server_data, 'foo.txt'),
...               md5('This is a foo text.'.encode()).hexdigest())
('/sample_files/foo.txt', False)

>>> download(join(server_data, 'foo.txt'),
...          md5('The wrong text.'.encode()).hexdigest())
Traceback (most recent call last):
ChecksumError: MD5 checksum mismatch for local resource at '/sample_files/foo.txt'.


Finally, we can download the file to a specified place in the file system:

>>> target_dir = tmpdir('download-target')
>>> print_(path)
>>> cat(path)
This is a foo text.
>>> is_temp
False


Trying to download a file in offline mode will result in an error:

>>> download = Download(cache=None, offline=True)
Traceback (most recent call last):


As an exception to this rule, file system paths and URLs in the file scheme will still work:

>>> cat(download(join(server_data, 'foo.txt'))[0])
This is a foo text.
This is a foo text.

>>> remove(path)


In order to make use of the download cache, we need to configure the download utility differently. To do this, we pass a directory path as the cache attribute upon instantiation:

>>> cache = tmpdir('download-cache')

##### Simple usage

When using the cache, a file will be stored in the cache directory when it is first downloaded. The file system path returned by the download utility points to the cached copy:

>>> ls(cache)
>>> print_(path)
>>> cat(path)
This is a foo text.
>>> is_temp
False


Whenever the file is downloaded again, the cached copy is used. Let’s change the file on the server to see this:

>>> write(server_data, 'foo.txt', 'The wrong text.')
>>> print_(path)
>>> cat(path)
This is a foo text.


If we specify an MD5 checksum for a file that is already in the cache, the cached copy’s checksum will be verified:

>>> download(server_url+'foo.txt', md5('The wrong text.'.encode()).hexdigest())
Traceback (most recent call last):


Trying to access another file at a different URL which has the same base name will result in the cached copy being used:

>>> mkdir(server_data, 'other')
>>> write(server_data, 'other', 'foo.txt', 'The wrong text.')
>>> print_(path)
>>> cat(path)
This is a foo text.


Given a target path for the download, the utility will provide a copy of the file at that location both when first downloading the file and when using a cached copy:

>>> remove(cache, 'foo.txt')
>>> ls(cache)
>>> write(server_data, 'foo.txt', 'This is a foo text.')

>>> path, is_temp = download(server_url+'foo.txt',
>>> print_(path)
>>> cat(path)
This is a foo text.
>>> is_temp
False
>>> ls(cache)
- foo.txt

>>> remove(path)
>>> write(server_data, 'foo.txt', 'The wrong text.')

>>> path, is_temp = download(server_url+'foo.txt',
>>> print_(path)
>>> cat(path)
This is a foo text.
>>> is_temp
False


In offline mode, downloads from any URL will be successful if the file is found in the cache:

>>> download = Download(cache=cache, offline=True)
This is a foo text.


Local resources will be cached just like any others since download caches are sometimes used to create source distributions:

>>> remove(cache, 'foo.txt')
>>> ls(cache)

>>> write(server_data, 'foo.txt', 'This is a foo text.')

>>> cat(download('file:' + join(server_data, 'foo.txt'), path=path)[0])
This is a foo text.
>>> ls(cache)
- foo.txt

>>> remove(cache, 'foo.txt')

>>> cat(download(join(server_data, 'foo.txt'), path=path)[0])
This is a foo text.
>>> ls(cache)
- foo.txt

>>> remove(cache, 'foo.txt')


However, resources with checksum mismatches will not be copied to the cache:

>>> download(server_url+'foo.txt', md5('The wrong text.'.encode()).hexdigest())
Traceback (most recent call last):
>>> ls(cache)

>>> remove(path)


If the file is completely missing it should notify the user of the error:

>>> download(server_url+'bar.txt') # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
Traceback (most recent call last):
...
...404...
>>> ls(cache)


Finally, let’s see what happens if the download cache to be used doesn’t exist as a directory in the file system yet:

>>> Download(cache=join(cache, 'non-existent'))(server_url+'foo.txt')
Traceback (most recent call last):
UserError: The directory:


>>> download = Download(cache=cache, namespace='test')


The namespace sub-directory hasn’t been created yet:

>>> ls(cache)


Downloading a file now creates the namespace sub-directory and places a copy of the file inside it:

>>> path, is_temp = download(server_url+'foo.txt')
>>> print_(path)
>>> ls(cache)
d test
>>> ls(cache, 'test')
- foo.txt
>>> cat(path)
This is a foo text.
>>> is_temp
False


The next time we want to download that file, the copy from inside the cache namespace is used. To see this clearly, we put a file with the same name but different content both on the server and in the cache’s root directory:

>>> write(server_data, 'foo.txt', 'The wrong text.')
>>> write(cache, 'foo.txt', 'The wrong text.')

>>> path, is_temp = download(server_url+'foo.txt')
>>> print_(path)
>>> cat(path)
This is a foo text.

>>> rmdir(cache, 'test')
>>> remove(cache, 'foo.txt')
>>> write(server_data, 'foo.txt', 'This is a foo text.')

##### Using a hash of the URL as the filename in the cache

So far, the base name of the downloaded file read from the URL has been used for the name of the cached copy of the file. This may not be desirable in some cases, for example when downloading files from different locations that have the same base name due to some naming convention, or if the file content depends on URL parameters. In such cases, an MD5 hash of the complete URL may be used as the filename in the cache:

>>> download = Download(cache=cache, hash_name=True)
>>> print_(path)
>>> cat(path)
This is a foo text.
>>> ls(cache)
- 09f5793fcdc1716727f72d49519c688d


The path was printed just to illustrate matters; we cannot know the real checksum since we don’t know which port the server happens to listen at when the test is run, so we don’t actually know the full URL of the file. Let’s check that the checksum actually belongs to the particular URL used:

>>> (path.lower() ==
...  join(cache, md5((server_url+'foo.txt').encode()).hexdigest()).lower())
True


>>> write(server_data, 'foo.txt', 'The wrong text.')
True
>>> cat(path)
This is a foo text.
>>> ls(cache)
- 09f5793fcdc1716727f72d49519c688d


If we change the URL, even in such a way that it keeps the base name of the file the same, the file will be downloaded again this time and put in the cache under a different name:

>>> path2, is_temp = download(server_url+'other/foo.txt')
>>> print_(path2)
>>> path == path2
False
>>> (path2.lower() ==
...  join(cache, md5((server_url+'other/foo.txt').encode()).hexdigest()
...       ).lower())
True
>>> cat(path)
This is a foo text.
>>> cat(path2)
The wrong text.
>>> ls(cache)
- 09f5793fcdc1716727f72d49519c688d
- 537b6d73267f8f4447586989af8c470e

>>> remove(path)
>>> remove(path2)
>>> write(server_data, 'foo.txt', 'This is a foo text.')


#### Using the cache purely as a fall-back

Sometimes it is desirable to try downloading a file from the net if at all possible, and use the cache purely as a fall-back option when a server is down or if we are in offline mode. This mode is only in effect if a download cache is configured in the first place:

>>> download = Download(cache=cache, fallback=True)


>>> ls(cache)
>>> ls(cache)
- foo.txt
>>> cat(cache, 'foo.txt')
This is a foo text.
>>> is_temp
False


If the file cannot be served, the cached copy will be used:

>>> remove(server_data, 'foo.txt')
... else: print_('woops')
>>> cat(path)
This is a foo text.
>>> is_temp
False


Similarly, if the file is served but we’re in offline mode, we’ll fall back to using the cache:

>>> write(server_data, 'foo.txt', 'The wrong text.')
>>> get(server_url+'foo.txt')
'The wrong text.'

>>> offline_download = Download(cache=cache, offline=True, fallback=True)
>>> print_(path)
>>> cat(path)
This is a foo text.
>>> is_temp
False


However, when downloading the file normally with the cache being used in fall-back mode, the file will be downloaded from the net and the cached copy will be replaced with the new content:

>>> cat(download(server_url+'foo.txt')[0])
The wrong text.
>>> cat(cache, 'foo.txt')
The wrong text.


When trying to download a resource whose checksum does not match, the cached copy will neither be used nor overwritten:

>>> write(server_data, 'foo.txt', 'This is a foo text.')
Traceback (most recent call last):
>>> cat(cache, 'foo.txt')
The wrong text.


The configuration options explained so far derive from the build logic implemented by the calling code. Other options configure the download utility for use in a particular project or buildout run; they are read from the buildout configuration section. The latter can be passed directly as the first argument to the download utility’s constructor.

>>> download = Download({'download-cache': cache}, namespace='cmmi')


If the download-cache option specifies a relative path, it is understood relative to the current working directory, or to the buildout directory if that is given:

>>> download = Download({'download-cache': 'relative-cache'})
/sample-buildout/relative-cache/

>>> download = Download({'directory': join(sample_buildout, 'root'),
/sample-buildout/root/relative-cache/


Keyword parameters take precedence over the corresponding options:

>>> download = Download({'download-cache': cache}, cache=None)
None


Whether to assume offline mode can be inferred from either the offline or the install-from-cache option. As usual with zc.buildout, these options must assume one of the values ‘true’ and ‘false’:

>>> download = Download({'offline': 'true'})
True

>>> download = Download({'offline': 'false'})
False

>>> download = Download({'install-from-cache': 'true'})
True

>>> download = Download({'install-from-cache': 'false'})
False


These two options are combined using logical ‘or’:

>>> download = Download({'offline': 'true', 'install-from-cache': 'false'})
True

>>> download = Download({'offline': 'false', 'install-from-cache': 'true'})
True


The offline keyword parameter takes precedence over both the offline and install-from-cache options:

>>> download = Download({'offline': 'true'}, offline=False)
False

>>> download = Download({'install-from-cache': 'false'}, offline=True)
True


#### Regressions

MD5 checksum calculation needs to be reliable on all supported systems, which requires text files to be treated as binary to avoid implicit line-ending conversions:

>>> text = 'First line of text.\r\nSecond line.\r\n'
>>> f = open(join(server_data, 'foo.txt'), 'wb')
>>> _ = f.write(text.encode())
>>> f.close()
...                            md5(text.encode()).hexdigest())
>>> remove(path)


When “downloading” a directory given by file-system path or file: URL and using a download cache at the same time, the cached directory wasn’t handled correctly. Consequently, the cache was defeated and an attempt to cache the directory a second time broke. This is how it should work:

>>> download = Download(cache=cache)
>>> dirpath = join(server_data, 'some_directory')
>>> mkdir(dirpath)


If we now modify the source tree, the second download will produce the original one from the cache:

>>> mkdir(join(dirpath, 'foo'))
>>> ls(dirpath)
d foo
>>> ls(dest)


#### Clean up

>>> ls(tempfile.tempdir)


Reset the global temporary directory:

>>> tempfile.tempdir = old_tempdir


Normally, when distributions are installed, if any processing is needed, they are downloaded from the internet to a temporary directory and then installed from there. A download cache can be used to avoid the download step. This can be useful to reduce network access and to create source distributions of an entire buildout.

In this example, we’ll create a directory to hold the cache:

>>> cache = tmpdir('cache')


>>> write('buildout.cfg',
... '''
... [buildout]
... parts = eggs
...
... [eggs]
... recipe = zc.recipe.egg
... eggs = demo ==0.2
... ''' % globals())


>>> print_(get(link_server), end='')
<html><body>
<a href="bigdemo-0.1-py2.4.egg">bigdemo-0.1-py2.4.egg</a><br>
<a href="demo-0.1-py2.4.egg">demo-0.1-py2.4.egg</a><br>
<a href="demo-0.2-py2.4.egg">demo-0.2-py2.4.egg</a><br>
<a href="demo-0.3-py2.4.egg">demo-0.3-py2.4.egg</a><br>
<a href="demo-0.4c1-py2.4.egg">demo-0.4c1-py2.4.egg</a><br>
<a href="demoneeded-1.0.zip">demoneeded-1.0.zip</a><br>
<a href="demoneeded-1.1.zip">demoneeded-1.1.zip</a><br>
<a href="demoneeded-1.2c1.zip">demoneeded-1.2c1.zip</a><br>
<a href="du_zipped-1.0-pyN.N.egg">du_zipped-1.0-pyN.N.egg</a><br>
<a href="extdemo-1.4.zip">extdemo-1.4.zip</a><br>
<a href="index/">index/</a><br>
<a href="other-1.0-py2.4.egg">other-1.0-py2.4.egg</a><br>
</body></html>


We’ll enable logging on the link server so we can see what’s going on:

>>> _ = get(link_server+'enable_server_logging')
GET 200 /enable_server_logging


If we run the buildout, we’ll see the eggs installed from the link server as usual:

>>> print_(system(buildout), end='')
GET 200 /
GET 200 /demo-0.2-py2.4.egg
GET 200 /demoneeded-1.1.zip
Installing eggs.
Getting distribution for 'demo==0.2'.
Got demo 0.2.
Getting distribution for 'demoneeded'.
Got demoneeded 1.1.
Generated script '/sample-buildout/bin/demo'.


We’ll also get the download cache populated. The buildout doesn’t put files in the cache directly. It creates an intermediate directory, dist:

>>> ls(cache)
d  dist

>>> ls(cache, 'dist')
-  demo-0.2-py2.4.egg
-  demoneeded-1.1.zip


If we remove the installed eggs from eggs directory and re-run the buildout:

>>> import os
>>> for  f in os.listdir('eggs'):
...     if f.startswith('demo'):
...         remove('eggs', f)

>>> print_(system(buildout), end='')
GET 200 /
Updating eggs.
Getting distribution for 'demo==0.2'.
Got demo 0.2.
Getting distribution for 'demoneeded'.
Got demoneeded 1.1.


A download cache can be used as the basis of application source releases. In an application source release, we want to distribute an application that can be built without making any network accesses. In this case, we distribute a buildout with download cache and tell the buildout to install from the download cache only, without making network accesses. The buildout install-from-cache option can be used to signal that packages should be installed only from the download cache.

Let’s remove our installed eggs and run the buildout with the install-from-cache option set to true:

>>> for  f in os.listdir('eggs'):
...     if f.startswith('demo'):
...         remove('eggs', f)

>>> write('buildout.cfg',
... '''
... [buildout]
... parts = eggs
... install-from-cache = true
...
... [eggs]
... recipe = zc.recipe.egg
... eggs = demo
... ''' % globals())

>>> print_(system(buildout), end='')
Uninstalling eggs.
Installing eggs.
Getting distribution for 'demo'.
Got demo 0.2.
Getting distribution for 'demoneeded'.
Got demoneeded 1.1.
Generated script '/sample-buildout/bin/demo'.


### Caching extended configuration

As mentioned in the general buildout documentation, configuration files can extend each other, including the ability to download configuration being extended from a URL. If desired, zc.buildout caches downloaded configuration in order to be able to use it when run offline.

As we’re going to talk about downloading things, let’s start an HTTP server. Also, all of the following will take place inside the sample buildout.

>>> server_data = tmpdir('server_data')
>>> server_url = start_server(server_data)
>>> cd(sample_buildout)


We also use a fresh directory for temporary files in order to make sure that all temporary files have been cleaned up in the end:

>>> import tempfile
>>> old_tempdir = tempfile.tempdir
>>> tempfile.tempdir = tmpdir('tmp')


#### Basic use of the extends cache

We put some base configuration on a server and reference it from a sample buildout:

>>> write(server_data, 'base.cfg', """\
... [buildout]
... parts =
... foo = bar
... """)

>>> write('buildout.cfg', """\
... [buildout]
... extends = %sbase.cfg
... """ % server_url)


When trying to run this buildout offline, we’ll find that we cannot read all of the required configuration:

>>> print_(system(buildout + ' -o'))
While:
Initializing.


Trying the same online, we can:

>>> print_(system(buildout))
Unused options for buildout: 'foo'.


As long as we haven’t said anything about caching downloaded configuration, nothing gets cached. Offline mode will still cause the buildout to fail:

>>> print_(system(buildout + ' -o'))
While:
Initializing.


Let’s now specify a cache for base configuration files. This cache is different from the download cache used by recipes for caching distributions and other files; one might, however, use a namespace subdirectory of the download cache for it. The configuration cache we specify will be created when running buildout and the base.cfg file will be put in it (with the file name being a hash of the complete URL):

>>> mkdir('cache')
>>> write('buildout.cfg', """\
... [buildout]
... extends = %sbase.cfg
... extends-cache = cache
... """ % server_url)

>>> print_(system(buildout))
Unused options for buildout: 'foo'.

>>> cache = join(sample_buildout, 'cache')
>>> ls(cache)
-  5aedc98d7e769290a29d654a591a3a45

>>> import os
>>> cat(cache, os.listdir(cache)[0])
[buildout]
parts =
foo = bar


We can now run buildout offline as it will read base.cfg from the cache:

>>> print_(system(buildout + ' -o'))
Unused options for buildout: 'foo'.


The cache is being used purely as a fall-back in case we are offline or don’t have access to a configuration file to be downloaded. As long as we are online, buildout attempts to download a fresh copy of each file even if a cached copy of the file exists. To see this, we put different configuration in the same place on the server and run buildout in offline mode so it takes base.cfg from the cache:

>>> write(server_data, 'base.cfg', """\
... [buildout]
... parts =
... bar = baz
... """)

>>> print_(system(buildout + ' -o'))
Unused options for buildout: 'foo'.


>>> print_(system(buildout))
Unused options for buildout: 'bar'.


Trying offline mode again, the new version will be used as it has been put in the cache now:

>>> print_(system(buildout + ' -o'))
Unused options for buildout: 'bar'.


Clean up:

>>> rmdir(cache)


#### Specifying extends cache and offline mode

Normally, the values of buildout options such as the location of a download cache or whether to use offline mode are determined by first reading the user’s default configuration, updating it with the project’s configuration and finally applying command-line options. User and project configuration are assembled by reading a file such as ~/.buildout/default.cfg, buildout.cfg or a URL given on the command line, recursively (depth-first) downloading any base configuration specified by the buildout:extends option read from each of those config files, and finally evaluating each config file to provide default values for options not yet read.

This works fine for all options that do not influence how configuration is downloaded in the first place. The extends-cache and offline options, however, are treated differently from the procedure described in order to make it simple and obvious to see where a particular configuration file came from under any particular circumstances.

• Offline and extends-cache settings are read from the two root config files exclusively. Otherwise one could construct configuration files that, when read, imply that they should have been read from a different source than they have. Also, specifying the extends cache within a file that might have to be taken from the cache before being read wouldn’t make a lot of sense.
• Offline and extends-cache settings given by the user’s defaults apply to the process of assembling the project’s configuration. If no extends cache has been specified by the user’s default configuration, the project’s root config file must be available, be it from disk or from the net.
• Offline mode turned on by the -o command line option is honoured from the beginning even though command line options are applied to the configuration last. If offline mode is not requested by the command line, it may be switched on by either the user’s or the project’s config root.
##### Extends cache

Let’s see the above rules in action. We create a new home directory for our user and write user and project configuration that recursively extends online bases, using different caches:

>>> mkdir('home')
>>> mkdir('home', '.buildout')
>>> mkdir('cache')
>>> mkdir('user-cache')
>>> os.environ['HOME'] = join(sample_buildout, 'home')
>>> write('home', '.buildout', 'default.cfg', """\
... [buildout]
... extends = fancy_default.cfg
... extends-cache = user-cache
... """)
>>> write('home', '.buildout', 'fancy_default.cfg', """\
... [buildout]
... extends = %sbase_default.cfg
... """ % server_url)
>>> write(server_data, 'base_default.cfg', """\
... [buildout]
... foo = bar
... offline = false
... """)

>>> write('buildout.cfg', """\
... [buildout]
... extends = fancy.cfg
... extends-cache = cache
... """)
>>> write('fancy.cfg', """\
... [buildout]
... extends = %sbase.cfg
... """ % server_url)
>>> write(server_data, 'base.cfg', """\
... [buildout]
... parts =
... offline = false
... """)


Buildout will now assemble its configuration from all of these 6 files, defaults first. The online resources end up in the respective extends caches:

>>> print_(system(buildout))
Unused options for buildout: 'foo'.

>>> ls('user-cache')
-  10e772cf422123ef6c64ae770f555740
>>> cat('user-cache', os.listdir('user-cache')[0])
[buildout]
foo = bar
offline = false

>>> ls('cache')
-  c72213127e6eb2208a3e1fc1dba771a7
>>> cat('cache', os.listdir('cache')[0])
[buildout]
parts =
offline = false


If, on the other hand, the extends caches are specified in files that get extended themselves, they won’t be used for assembling the configuration they belong to (user’s or project’s, resp.). The extends cache specified by the user’s defaults does, however, apply to downloading project configuration. Let’s rewrite the config files, clean out the caches and re-run buildout:

>>> write('home', '.buildout', 'default.cfg', """\
... [buildout]
... extends = fancy_default.cfg
... """)
>>> write('home', '.buildout', 'fancy_default.cfg', """\
... [buildout]
... extends = %sbase_default.cfg
... extends-cache = user-cache
... """ % server_url)

>>> write('buildout.cfg', """\
... [buildout]
... extends = fancy.cfg
... """)
>>> write('fancy.cfg', """\
... [buildout]
... extends = %sbase.cfg
... extends-cache = cache
... """ % server_url)

>>> remove('user-cache', os.listdir('user-cache')[0])
>>> remove('cache', os.listdir('cache')[0])

>>> print_(system(buildout))
Unused options for buildout: 'foo'.

>>> ls('user-cache')
>>> cat('user-cache', os.listdir('user-cache')[0])
[buildout]
parts =
offline = false

>>> ls('cache')


Clean up:

>>> rmdir('user-cache')
>>> rmdir('cache')


Offline mode and installation from cache —————————-~~~~~~~~~~~~

If we run buildout in offline mode now, it will fail because it cannot get at the remote configuration file needed by the user’s defaults:

>>> print_(system(buildout + ' -o'))
While:
Initializing.


Let’s now successively turn on offline mode by different parts of the configuration and see when buildout applies this setting in each case:

>>> write('home', '.buildout', 'default.cfg', """\
... [buildout]
... extends = fancy_default.cfg
... offline = true
... """)
>>> print_(system(buildout))
While:
Initializing.

>>> write('home', '.buildout', 'default.cfg', """\
... [buildout]
... extends = fancy_default.cfg
... """)
>>> write('home', '.buildout', 'fancy_default.cfg', """\
... [buildout]
... extends = %sbase_default.cfg
... offline = true
... """ % server_url)
>>> print_(system(buildout))
While:
Initializing.

>>> write('home', '.buildout', 'fancy_default.cfg', """\
... [buildout]
... extends = %sbase_default.cfg
... """ % server_url)
>>> write('buildout.cfg', """\
... [buildout]
... extends = fancy.cfg
... offline = true
... """)
>>> print_(system(buildout))
While:
Initializing.

>>> write('buildout.cfg', """\
... [buildout]
... extends = fancy.cfg
... """)
>>> write('fancy.cfg', """\
... [buildout]
... extends = %sbase.cfg
... offline = true
... """ % server_url)
>>> print_(system(buildout))
Unused options for buildout: 'foo'.


The install-from-cache option is treated accordingly:

>>> write('home', '.buildout', 'default.cfg', """\
... [buildout]
... extends = fancy_default.cfg
... install-from-cache = true
... """)
>>> print_(system(buildout))
While:
Initializing.

>>> write('home', '.buildout', 'default.cfg', """\
... [buildout]
... extends = fancy_default.cfg
... """)
>>> write('home', '.buildout', 'fancy_default.cfg', """\
... [buildout]
... extends = %sbase_default.cfg
... install-from-cache = true
... """ % server_url)
>>> print_(system(buildout))
While:
Initializing.

>>> write('home', '.buildout', 'fancy_default.cfg', """\
... [buildout]
... extends = %sbase_default.cfg
... """ % server_url)
>>> write('buildout.cfg', """\
... [buildout]
... extends = fancy.cfg
... install-from-cache = true
... """)
>>> print_(system(buildout))
While:
Initializing.

>>> write('buildout.cfg', """\
... [buildout]
... extends = fancy.cfg
... """)
>>> write('fancy.cfg', """\
... [buildout]
... extends = %sbase.cfg
... install-from-cache = true
... """ % server_url)
>>> print_(system(buildout))
While:
Installing.
An internal error occured ...

>>> rmdir('home', '.buildout')


While offline mode forbids network access completely, ‘newest’ mode determines whether to look for updated versions of a resource even if some version of it is already present locally. If we run buildout in newest mode (newest = true), the configuration files are updated with each run:

>>> mkdir("cache")
>>> write(server_data, 'base.cfg', """\
... [buildout]
... parts =
... """)
>>> write('buildout.cfg', """\
... [buildout]
... extends-cache = cache
... extends = %sbase.cfg
... """ % server_url)
>>> print_(system(buildout))
>>> ls('cache')
-  5aedc98d7e769290a29d654a591a3a45
>>> cat('cache', os.listdir(cache)[0])
[buildout]
parts =


A change to base.cfg is picked up on the next buildout run:

>>> write(server_data, 'base.cfg', """\
... [buildout]
... parts =
... foo = bar
... """)
>>> print_(system(buildout + " -n"))
Unused options for buildout: 'foo'.
>>> cat('cache', os.listdir(cache)[0])
[buildout]
parts =
foo = bar


In contrast, when not using newest mode (newest = false), the files already present in the extends cache will not be updated:

>>> write(server_data, 'base.cfg', """\
... [buildout]
... parts =
... """)
>>> print_(system(buildout + " -N"))
Unused options for buildout: 'foo'.
>>> cat('cache', os.listdir(cache)[0])
[buildout]
parts =
foo = bar


Even when updating base configuration files with a buildout run, any given configuration file will be downloaded only once during that particular run. If some base configuration file is extended more than once, its cached copy is used:

>>> write(server_data, 'baseA.cfg', """\
... [buildout]
... extends = %sbase.cfg
... foo = bar
... """ % server_url)
>>> write(server_data, 'baseB.cfg', """\
... [buildout]
... extends-cache = cache
... extends = %sbase.cfg
... bar = foo
... """ % server_url)
>>> write('buildout.cfg', """\
... [buildout]
... extends-cache = cache
... extends = %sbaseA.cfg %sbaseB.cfg
... """ % (server_url, server_url))
>>> print_(system(buildout + " -n"))
Unused options for buildout: 'bar' 'foo'.


(XXX We patch download utility’s API to produce readable output for the test; a better solution would utilise the logging already done by the utility.)

>>> import zc.buildout

>>> zc.buildout.buildout.main([])
Not upgrading because not running a local buildout command.
Unused options for buildout: 'bar' 'foo'.

>>> zc.buildout.download.Download.download = old_download


#### The deprecated extended-by option

The buildout section used to recognise an option named extended-by that was deprecated at some point and removed in the 1.5 line. Since ignoring this option silently was considered harmful as a matter of principle, a UserError is raised if that option is encountered now:

>>> write(server_data, 'base.cfg', """\
... [buildout]
... parts =
... extended-by = foo.cfg
... """)
>>> print_(system(buildout))
While:
Initializing.
Error: No-longer supported "extended-by" option found in http://localhost/base.cfg.


#### Clean up

>>> ls(tempfile.tempdir)


Reset the global temporary directory:

>>> tempfile.tempdir = old_tempdir


### Using zc.buildout to run setup scripts

zc buildout has a convenience command for running setup scripts. Why? There are two reasons. If a setup script doesn’t import setuptools, you can’t use any setuptools-provided commands, like bdist_egg. When buildout runs a setup script, it arranges to import setuptools before running the script so setuptools-provided commands are available.

If you use a squeaky-clean Python to do your development, the setup script that would import setuptools because setuptools isn’t in the path. Because buildout requires setuptools and knows where it has installed a distribute egg, it adds the distribute egg to the Python path before running the script. To run a setup script, use the buildout setup command, passing the name of a script or a directory containing a setup script and arguments to the script. Let’s look at an example:

>>> mkdir('test')
>>> cd('test')
>>> write('setup.py',
... '''
... from distutils.core import setup
... setup(name='sample')
... ''')


We’ve created a super simple (stupid) setup script. Note that it doesn’t import setuptools. Let’s try running it to create an egg. We’ll use the buildout script from our sample buildout:

>>> print_(system(buildout+' setup'), end='')
... # doctest: +NORMALIZE_WHITESPACE
Error: The setup command requires the path to a setup script or
directory containing a setup script, and its arguments.


Oops, we forgot to give the name of the setup script:

>>> print_(system(buildout+' setup setup.py bdist_egg'))
... # doctest: +ELLIPSIS
Running setup script 'setup.py'.
...

>>> ls('dist')
-  sample-0.0.0-py2.5.egg


Note that we can specify a directory name. This is often shorter and preferred by the lazy :)

>>> print_(system(buildout+' setup . bdist_egg')) # doctest: +ELLIPSIS
Running setup script './setup.py'.
...


When a buildout is run, one of the first steps performed is to check for updates to either zc.buildout or distribute. To demonstrate this, we’ve created some “new releases” of buildout and distribute in a new_releases folder:

>>> ls(new_releases)
d  distribute
-  distribute-99.99-py2.4.egg
d  zc.buildout
-  zc.buildout-99.99-py2.4.egg


Let’s update the sample buildout.cfg to look in this area:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... index = %(new_releases)s
... parts = show-versions
... develop = showversions
...
... [show-versions]
... recipe = showversions
... """ % dict(new_releases=new_releases))


We’ll also include a recipe that echos the versions of distribute and zc.buildout used:

>>> mkdir(sample_buildout, 'showversions')

>>> write(sample_buildout, 'showversions', 'showversions.py',
... """
... import pkg_resources
... import sys
... print_ = lambda *a: sys.stdout.write(' '.join(map(str, a))+'\\n')
...
... class Recipe:
...
...     def __init__(self, buildout, name, options):
...         pass
...
...     def install(self):
...         for project in 'zc.buildout', 'distribute':
...             req = pkg_resources.Requirement.parse(project)
...             print_(project, pkg_resources.working_set.find(req).version)
...         return ()
...     update = install
... """)

>>> write(sample_buildout, 'showversions', 'setup.py',
... """
... from setuptools import setup
...
... setup(
...     name = "showversions",
...     entry_points = {'zc.buildout': ['default = showversions:Recipe']},
...     )
... """)


Now if we run the buildout, the buildout will upgrade itself to the new versions found in new releases:

>>> print_(system(buildout), end='')
Getting distribution for 'zc.buildout>=1.99'.
Got zc.buildout 99.99.
Getting distribution for 'distribute'.
Got distribute 99.99.
zc.buildout version 99.99,
distribute version 99.99;
restarting.
Generated script '/sample-buildout/bin/buildout'.
Develop: '/sample-buildout/showversions'
Installing show-versions.
zc.buildout 99.99
distribute 99.99


Our buildout script has been updated to use the new eggs:

>>> cat(sample_buildout, 'bin', 'buildout')
#!/usr/local/bin/python2.7
<BLANKLINE>
import sys
sys.path[0:0] = [
'/sample-buildout/eggs/zc.buildout-99.99-py2.4.egg',
'/sample-buildout/eggs/distribute-99.99-py2.4.egg',
]
<BLANKLINE>
import zc.buildout.buildout
<BLANKLINE>
if __name__ == '__main__':
sys.exit(zc.buildout.buildout.main())


Now, let’s recreate the sample buildout. If we specify constraints on the versions of zc.buildout and distribute to use, running the buildout will install earlier versions of these packages:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... index = %(new_releases)s
... parts = show-versions
... develop = showversions
... zc.buildout-version = < 99
... distribute-version = < 99
...
... [show-versions]
... recipe = showversions
... """ % dict(new_releases=new_releases))


Now we can see that we actually “upgrade” to an earlier version.

>>> print_(system(buildout), end='')
zc.buildout version 1.4.4;
distribute version 0.6;
restarting.
Generated script '/sample-buildout/bin/buildout'.
Develop: '/sample-buildout/showversions'
Updating show-versions.
zc.buildout 1.0.0
distribute 0.6


There are a number of cases, described below, in which the updates don’t happen.

We won’t upgrade in offline mode:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... index = %(new_releases)s
... parts = show-versions
... develop = showversions
...
... [show-versions]
... recipe = showversions
... """ % dict(new_releases=new_releases))

>>> print_(system(buildout+' -o'), end='')
Develop: '/sample-buildout/showversions'
Updating show-versions.
zc.buildout 1.0.0
distribute 0.6


>>> print_(system(buildout+' -N'), end='')
Develop: '/sample-buildout/showversions'
Updating show-versions.
zc.buildout 1.0.0
distribute 0.6


We also won’t upgrade if the buildout script being run isn’t in the buildouts bin directory. To see this we’ll create a new buildout directory:

>>> sample_buildout2 = tmpdir('sample_buildout2')
>>> write(sample_buildout2, 'buildout.cfg',
... """
... [buildout]
... index = %(new_releases)s
... parts =
... """ % dict(new_releases=new_releases))

>>> cd(sample_buildout2)
>>> print_(system(buildout), end='')
Creating directory '/sample_buildout2/bin'.
Creating directory '/sample_buildout2/parts'.
Creating directory '/sample_buildout2/eggs'.
Creating directory '/sample_buildout2/develop-eggs'.
Getting distribution for 'zc.buildout>=1.99'.
Got zc.buildout 99.99.
Getting distribution for 'distribute'.
Got distribute 99.99.
Not upgrading because not running a local buildout command.

>>> ls('bin')


### Debugging buildouts

Buildouts can be pretty complex. When things go wrong, it isn’t always obvious why. Errors can occur due to problems in user input or due to bugs in zc.buildout or recipes. When an error occurs, Python’s post-mortem debugger can be used to inspect the state of the buildout or recipe code were there error occured. To enable this, use the -D option to the buildout. Let’s create a recipe that has a bug:

>>> mkdir(sample_buildout, 'recipes')

>>> write(sample_buildout, 'recipes', 'mkdir.py',
... """
... import os, zc.buildout
...
... class Mkdir:
...
...     def __init__(self, buildout, name, options):
...         self.name, self.options = name, options
...         options['path'] = os.path.join(
...                               buildout['buildout']['directory'],
...                               options['path'],
...                               )
...
...     def install(self):
...         directory = self.options['directory']
...         os.mkdir(directory)
...         return directory
...
...     def update(self):
...         pass
... """)

>>> write(sample_buildout, 'recipes', 'setup.py',
... """
... from setuptools import setup
...
... setup(name = "recipes",
...       entry_points = {'zc.buildout': ['mkdir = mkdir:Mkdir']},
...       )
... """)


And create a buildout that uses it:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... parts = data-dir
...
... [data-dir]
... recipe = recipes:mkdir
... path = mystuff
... """)


If we run the buildout, we’ll get an error:

>>> print_(system(buildout), end='')
Develop: '/sample-buildout/recipes'
Installing data-dir.
While:
Installing data-dir.
Error: Missing option: data-dir:directory


If we want to debug the error, we can add the -D option. Here’s we’ll supply some input:

>>> print_(system(buildout+" -D", """\
... up
... p sorted(self.options.keys())
... q
... """), end='')
Develop: '/sample-buildout/recipes'
Installing data-dir.
> /zc/buildout/buildout.py(925)__getitem__()
-> raise MissingOption("Missing option: %s:%s" % (self.name, key))
(Pdb) > /sample-buildout/recipes/mkdir.py(14)install()
-> directory = self.options['directory']
(Pdb) ['path', 'recipe']
(Pdb) While:
Installing data-dir.
Traceback (most recent call last):
File "/zc/buildout/buildout.py", line 1352, in main
getattr(buildout, command)(args)
File "/zc/buildout/buildout.py", line 383, in install
installed_files = self[part]._call(recipe.install)
File "/zc/buildout/buildout.py", line 961, in _call
return f()
File "/sample-buildout/recipes/mkdir.py", line 14, in install
directory = self.options['directory']
File "/zc/buildout/buildout.py", line 925, in __getitem__
raise MissingOption("Missing option: %s:%s" % (self.name, key))
MissingOption: Missing option: data-dir:directory
<BLANKLINE>
Starting pdb:


### Testing Support

The zc.buildout.testing module provides an API that can be used when writing recipe tests. This API is documented below. Many examples of using this API can be found in the zc.buildout, zc.recipe.egg, and zc.recipe.testrunner tests.

#### zc.buildout.testing.buildoutSetUp(test)

The buildoutSetup function can be used as a doctest setup function. It creates a sample buildout that can be used by tests, changing the current working directory to the sample_buildout. It also adds a number of names to the test namespace:

sample_buildout
This is the name of a buildout with a basic configuration.
buildout
This is the path of the buildout script in the sample buildout.
ls(*path)
List the contents of a directory. The directory path is provided as one or more strings, to be joined with os.path.join.
cat(*path)

Display the contents of a file. The file path is provided as one or more strings, to be joined with os.path.join.

On Windows, if the file doesn’t exist, the function will try adding a ‘-script.py’ suffix. This helps to work around a difference in script generation on windows.

mkdir(*path)
Create a directory. The directory path is provided as one or more strings, to be joined with os.path.join.
rmdir(*path)
Remove a directory. The directory path is provided as one or more strings, to be joined with os.path.join.
remove(*path)
Remove a directory or file. The path is provided as one or more strings, to be joined with os.path.join.
tmpdir(name)

Create a temporary directory with the given name. The directory will be automatically removed at the end of the test. The path of the created directory is returned.

Further, if the the normalize_path normlaizing substitution (see below) is used, then any paths starting with this path will be normalized to:

/name/restofpath


No two temporary directories can be created with the same name. A directory created with tmpdir can be removed with rmdir and recreated.

Note that the sample_buildout directory is created by calling this function.

write(*path_and_contents)
Create a file. The file path is provided as one or more strings, to be joined with os.path.join. The last argument is the file contents.
system(command, input='')
Execute a system command with the given input passed to the command’s standard input. The output (error and regular output) from the command is returned.
get(url)
Get a web page.
cd(*path)

Change to the given directory. The directory path is provided as one or more strings, to be joined with os.path.join.

The directory will be reset at the end of the test.

uncd()
Change to the directory that was current prior to the previous call to cd. You can call cd multiple times and then uncd the same number of times to return to the same location.
join(*path)
A convenient reference to os.path.join.
register_teardown(func)
Register a tear-down function. The function will be called with no arguments at the end of the test.
start_server(path)

Start a web server on the given path. The server will be shut down at the end of the test. The server URL is returned.

You can cause the server to start and stop logging it’s output using:

>>> get(server_url+'enable_server_logging')


and:

>>> get(server_url+'disable_server_logging')


This can be useful to see how buildout is interacting with a server.

sdist(setup, dest)
Create a source distribution by running the given setup file and placing the result in the given destination directory. If the setup argument is a directory, the thge setup.py file in that directory is used.
bdist_egg(setup, dest)
Create an egg by running the given setup file and placing the result in the given destination directory. If the setup argument is a directory, then the setup.py file in that directory is used.

#### zc.buildout.testing.buildoutTearDown(test)

Tear down everything set up by zc.buildout.testing.buildoutSetUp. Any functions passed to register_teardown are called as well.

#### install(project, destination)

Install eggs for a given project into a destination. If the destination is a test object, then the eggs directory of the sample buildout (sample_buildout) defined by the test will be used. Tests will use this to install the distributions for the packages being tested (and their dependencies) into a sample buildout. The egg to be used should already be loaded, by importing one of the modules provided, before calling this function.

#### install_develop(project, destination)

Like install, but a develop egg is installed even if the current egg if not a develop egg.

#### Output normalization

Recipe tests often generate output that is dependent on temporary file locations, operating system conventions or Python versions. To deal with these dependencies, we often use zope.testing.renormalizing.RENormalizing to normalize test output. zope.testing.renormalizing.RENormalizing takes pairs of regular expressions and substitutions. The zc.buildout.testing module provides a few helpful variables that define regular-expression/substitution pairs that you can pass to zope.testing.renormalizing.RENormalizing.

normalize_path
Converts tests paths, based on directories created with tmpdir(), to simple paths.
normalize_script
On Unix-like systems, scripts are implemented in single files without suffixes. On windows, scripts are implemented with 2 files, a -script.py file and a .exe file. This normalization converts directory listings of Windows scripts to the form generated on UNix-like systems.
normalize_egg_py
Normalize Python version and platform indicators, if specified, in egg names.

### Python API for egg and script installation

The easy_install module provides some functions to provide support for egg and script installation. It provides functionality at the python level that is similar to easy_install, with a few exceptions:

• By default, we look for new packages and the packages that they depend on. This is somewhat like (and uses) the –upgrade option of easy_install, except that we also upgrade required packages.
• If the highest-revision package satisfying a specification is already present, then we don’t try to get another one. This saves a lot of search time in the common case that packages are pegged to specific versions.
• If there is a develop egg that satisfies a requirement, we don’t look for additional distributions. We always give preference to develop eggs.
• Distutils options for building extensions can be passed.

#### Distribution installation

The easy_install module provides a function, install, for installing one or more packages and their dependencies. The install function takes 2 positional arguments:

• An iterable of setuptools requirement strings for the distributions to be installed, and
• A destination directory to install to and to satisfy requirements from. The destination directory can be None, in which case, no new distributions are downloaded and there will be an error if the needed distributions can’t be found among those already installed.

It supports a number of optional keyword arguments:

A sequence of URLs, file names, or directories to look for links to distributions.
index

The URL of an index server, or almost any other valid URL. :)

If not specified, the Python Package Index, http://pypi.python.org/simple/, is used. You can specify an alternate index with this option. If you use the links option and if the links point to the needed distributions, then the index can be anything and will be largely ignored. In the examples, here, we’ll just point to an empty directory on our link server. This will make our examples run a little bit faster.

path
A list of additional directories to search for locally-installed distributions.
working_set
An existing working set to be augmented with additional distributions, if necessary to satisfy requirements. This allows you to call install multiple times, if necessary, to gather multiple sets of requirements.
A boolean value indicating whether to search for new distributions when already-installed distributions meet the requirement. When this is true, the default, and when the destination directory is not None, then the install function will search for the newest distributions that satisfy the requirements.
versions
A dictionary mapping project names to version numbers to be used when selecting distributions. This can be used to specify a set of distribution versions independent of other requirements.
A flag indicating whether to search for dependencies using the setup dependency_links metadata or not. If true, links are searched for using dependency_links in preference to other locations. Defaults to true.
relative_paths
Adjust egg paths so they are relative to the script path. This allows scripts to work when scripts and eggs are moved, as long as they are both moved in the same way.

The install method returns a working set containing the distributions needed to meet the given requirements.

We have a link server that has a number of eggs:

>>> print_(get(link_server), end='')
<html><body>
<a href="bigdemo-0.1-py2.4.egg">bigdemo-0.1-py2.4.egg</a><br>
<a href="demo-0.1-py2.4.egg">demo-0.1-py2.4.egg</a><br>
<a href="demo-0.2-py2.4.egg">demo-0.2-py2.4.egg</a><br>
<a href="demo-0.3-py2.4.egg">demo-0.3-py2.4.egg</a><br>
<a href="demo-0.4c1-py2.4.egg">demo-0.4c1-py2.4.egg</a><br>
<a href="demoneeded-1.0.zip">demoneeded-1.0.zip</a><br>
<a href="demoneeded-1.1.zip">demoneeded-1.1.zip</a><br>
<a href="demoneeded-1.2c1.zip">demoneeded-1.2c1.zip</a><br>
<a href="du_zipped-1.0-pyN.N.egg">du_zipped-1.0-pyN.N.egg</a><br>
<a href="extdemo-1.4.zip">extdemo-1.4.zip</a><br>
<a href="index/">index/</a><br>
<a href="other-1.0-py2.4.egg">other-1.0-py2.4.egg</a><br>
</body></html>


Let’s make a directory and install the demo egg to it, using the demo:

>>> dest = tmpdir('sample-install')
>>> import zc.buildout.easy_install
>>> ws = zc.buildout.easy_install.install(
...     ['demo==0.2'], dest,


We requested version 0.2 of the demo distribution to be installed into the destination server. We specified that we should search for links on the link server and that we should use the (empty) link server index directory as a package index.

The working set contains the distributions we retrieved.

>>> for dist in ws:
...     print_(dist)
demo 0.2
demoneeded 1.1


We got demoneeded because it was a dependency of demo.

And the actual eggs were added to the eggs directory.

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demoneeded-1.1-py2.4.egg


If we remove the version restriction on demo, but specify a false value for newest, no new distributions will be installed:

>>> ws = zc.buildout.easy_install.install(
>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demoneeded-1.1-py2.4.egg


If we leave off the newest option, we’ll get an update for demo:

>>> ws = zc.buildout.easy_install.install(
>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demo-0.3-py2.4.egg
d  demoneeded-1.1-py2.4.egg


Note that we didn’t get the newest versions available. There were release candidates for newer versions of both packages. By default, final releases are preferred. We can change this behavior using the prefer_final function:

>>> zc.buildout.easy_install.prefer_final(False)
True


The old setting is returned.

>>> ws = zc.buildout.easy_install.install(
>>> for dist in ws:
...     print_(dist)
demo 0.4c1
demoneeded 1.2c1

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demo-0.3-py2.4.egg
d  demo-0.4c1-py2.4.egg
d  demoneeded-1.1-py2.4.egg
d  demoneeded-1.2c1-py2.4.egg


Let’s put the setting back to the default.

>>> zc.buildout.easy_install.prefer_final(True)
False


We can supply additional distributions. We can also supply specifications for distributions that would normally be found via dependencies. We might do this to specify a specific version.

>>> ws = zc.buildout.easy_install.install(
...     ['demo', 'other', 'demoneeded==1.0'], dest,

>>> for dist in ws:
...     print_(dist)
demo 0.3
other 1.0
demoneeded 1.0

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demo-0.3-py2.4.egg
d  demo-0.4c1-py2.4.egg
d  demoneeded-1.0-py2.4.egg
d  demoneeded-1.1-py2.4.egg
d  demoneeded-1.2c1-py2.4.egg
d  other-1.0-py2.4.egg

>>> rmdir(dest)


#### Specifying version information independent of requirements

Sometimes it’s useful to specify version information independent of normal requirements specifications. For example, a buildout may need to lock down a set of versions, without having to put put version numbers in setup files or part definitions. If a dictionary is passed to the install function, mapping project names to version numbers, then the versions numbers will be used.

>>> ws = zc.buildout.easy_install.install(
...     versions = dict(demo='0.2', demoneeded='1.0'))
>>> [d.version for d in ws]
['0.2', '1.0']


In this example, we specified a version for demoneeded, even though we didn’t define a requirement for it. The versions specified apply to dependencies as well as the specified requirements.

If we specify a version that’s incompatible with a requirement, then we’ll get an error:

>>> from zope.testing.loggingsupport import InstalledHandler
>>> handler = InstalledHandler('zc.buildout.easy_install')
>>> import logging
>>> logging.getLogger('zc.buildout.easy_install').propagate = False

>>> ws = zc.buildout.easy_install.install(
...     versions = dict(demo='0.2', demoneeded='1.0'))
Traceback (most recent call last):
...

>>> print_(handler)
zc.buildout.easy_install DEBUG
Installing 'demo >0.2'.
zc.buildout.easy_install ERROR
The constraint, 0.2, is not consistent with the requirement, 'demo>0.2'.

>>> handler.clear()


If no versions are specified, a debugging message will be output reporting that a version was picked automatically:

>>> ws = zc.buildout.easy_install.install(
...     )

>>> print_(handler) # doctest: +ELLIPSIS
zc.buildout.easy_install DEBUG
Installing 'demo'.
zc.buildout.easy_install INFO
Getting distribution for 'demo'.
zc.buildout.easy_install INFO
Got demo 0.3.
zc.buildout.easy_install DEBUG
Picked: demo = 0.3
zc.buildout.easy_install DEBUG
Getting required 'demoneeded'
zc.buildout.easy_install DEBUG
required by demo 0.3.
zc.buildout.easy_install INFO
Getting distribution for 'demoneeded'.
zc.buildout.easy_install DEBUG
Running easy_install:...
zc.buildout.easy_install INFO
Got demoneeded 1.1.
zc.buildout.easy_install DEBUG
Picked: demoneeded = 1.1

zc.buildout.easy_install DEBUG
Installing ‘demo’.
zc.buildout.easy_install DEBUG
We have the best distribution that satisfies ‘demo’.
zc.buildout.easy_install DEBUG
Picked: demo = 0.3
zc.buildout.easy_install DEBUG
Getting required ‘demoneeded’
zc.buildout.easy_install DEBUG
required by demo 0.3.
zc.buildout.easy_install DEBUG
We have the best distribution that satisfies ‘demoneeded’.
zc.buildout.easy_install DEBUG
Picked: demoneeded = 1.1
>>> handler.uninstall()
>>> logging.getLogger('zc.buildout.easy_install').propagate = True


We can request that we get an error if versions are picked:

>>> zc.buildout.easy_install.allow_picked_versions(False)
True


(The old setting is returned.)

>>> ws = zc.buildout.easy_install.install(
...     )
Traceback (most recent call last):
...
UserError: Picked: demo = 0.3

>>> zc.buildout.easy_install.allow_picked_versions(True)
False


The function default_versions can be used to get and set default version information to be used when no version information is passes. If called with an argument, it sets the default versions:

>>> zc.buildout.easy_install.default_versions(dict(demoneeded='1'))
... # doctest: +ELLIPSIS
{...}


It always returns the previous default versions. If called without an argument, it simply returns the default versions without changing them:

>>> zc.buildout.easy_install.default_versions()
{'demoneeded': '1'}


So with the default versions set, we’ll get the requested version even if the versions option isn’t used:

>>> ws = zc.buildout.easy_install.install(
...     )

>>> [d.version for d in ws]
['0.3', '1.0']


Of course, we can unset the default versions by passing an empty dictionary:

>>> zc.buildout.easy_install.default_versions({})
{'demoneeded': '1'}

>>> ws = zc.buildout.easy_install.install(
...     )

>>> [d.version for d in ws]
['0.3', '1.1']


#### Script generation

The easy_install module provides support for creating scripts from eggs. It provides a function similar to setuptools except that it provides facilities for baking a script’s path into the script. This has two advantages:

• The eggs to be used by a script are not chosen at run time, making startup faster and, more importantly, deterministic.
• The script doesn’t have to import pkg_resources because the logic that pkg_resources would execute at run time is executed at script-creation time.

The scripts method can be used to generate scripts. Let’s create a destination directory for it to place them in:

>>> import tempfile
>>> bin = tmpdir('bin')


Now, we’ll use the scripts method to generate scripts in this directory from the demo egg:

>>> import sys
>>> scripts = zc.buildout.easy_install.scripts(
...     ['demo'], ws, sys.executable, bin)


the three arguments we passed were:

1. A sequence of distribution requirements. These are of the same form as setuptools requirements. Here we passed a single requirement, for the version 0.1 demo distribution.
2. A working set,
3. The destination directory.

The bin directory now contains a generated script:

>>> ls(bin)
-  demo


The return value is a list of the scripts generated:

>>> import os, sys
>>> if sys.platform == 'win32':
...     scripts == [os.path.join(bin, 'demo.exe'),
...                 os.path.join(bin, 'demo-script.py')]
... else:
...     scripts == [os.path.join(bin, 'demo')]
True


Note that in Windows, 2 files are generated for each script. A script file, ending in ‘-script.py’, and an exe file that allows the script to be invoked directly without having to specify the Python interpreter and without having to provide a ‘.py’ suffix.

The demo script run the entry point defined in the demo egg:

>>> cat(bin, 'demo') # doctest: +NORMALIZE_WHITESPACE
#!/usr/local/bin/python2.7
<BLANKLINE>
import sys
sys.path[0:0] = [
'/sample-install/demo-0.3-py2.4.egg',
'/sample-install/demoneeded-1.1-py2.4.egg',
]
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
sys.exit(eggrecipedemo.main())


Some things to note:

• The demo and demoneeded eggs are added to the beginning of sys.path.
• The module for the script entry point is imported and the entry point, in this case, ‘main’, is run.

Rather than requirement strings, you can pass tuples containing 3 strings:

• A script name,
• A module,
• An attribute expression for an entry point within the module.

For example, we could have passed entry point information directly rather than passing a requirement:

>>> scripts = zc.buildout.easy_install.scripts(
...     [('demo', 'eggrecipedemo', 'main')], ws,
...     sys.executable, bin)

>>> cat(bin, 'demo') # doctest: +NORMALIZE_WHITESPACE
#!/usr/local/bin/python2.7
<BLANKLINE>
import sys
sys.path[0:0] = [
'/sample-install/demo-0.3-py2.4.egg',
'/sample-install/demoneeded-1.1-py2.4.egg',
]
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
sys.exit(eggrecipedemo.main())


Passing entry-point information directly is handy when using eggs (or distributions) that don’t declare their entry points, such as distributions that aren’t based on setuptools.

The interpreter keyword argument can be used to generate a script that can be used to invoke the Python interactive interpreter with the path set based on the working set. This generated script can also be used to run other scripts with the path set on the working set:

>>> scripts = zc.buildout.easy_install.scripts(
...     ['demo'], ws, sys.executable, bin, interpreter='py')

>>> ls(bin)
-  demo
-  py

>>> if sys.platform == 'win32':
...     scripts == [os.path.join(bin, 'demo.exe'),
...                 os.path.join(bin, 'demo-script.py'),
...                 os.path.join(bin, 'py.exe'),
...                 os.path.join(bin, 'py-script.py')]
... else:
...     scripts == [os.path.join(bin, 'demo'),
...                 os.path.join(bin, 'py')]
True


The py script simply runs the Python interactive interpreter with the path set:

>>> cat(bin, 'py') # doctest: +NORMALIZE_WHITESPACE
#!/usr/local/bin/python2.7
<BLANKLINE>
import sys
<BLANKLINE>
sys.path[0:0] = [
'/sample-install/demo-0.3-pyN.N.egg',
'/sample-install/demoneeded-1.1-pyN.N.egg',
]
<BLANKLINE>
_interactive = True
if len(sys.argv) > 1:
_options, _args = __import__("getopt").getopt(sys.argv[1:], 'ic:m:')
_interactive = False
for (_opt, _val) in _options:
if _opt == '-i':
_interactive = True
elif _opt == '-c':
exec(_val)
elif _opt == '-m':
sys.argv[1:] = _args
_args = []
__import__("runpy").run_module(
_val, {}, "__main__", alter_sys=True)
<BLANKLINE>
if _args:
sys.argv[:] = _args
__file__ = _args[0]
del _options, _args
__file__f = open(__file__)
__file__f.close(); del __file__f
<BLANKLINE>
if _interactive:
del _interactive
__import__("code").interact(banner="", local=globals())


If invoked with a script name and arguments, it will run that script, instead.

>>> write('ascript', r'''
... "demo doc"
... import sys
... print_ = lambda *a: sys.stdout.write(' '.join(map(str, a))+'\n')
... print_(sys.argv)
... print_((__name__, __file__, __doc__))
... ''')
>>> print_(system(join(bin, 'py')+' ascript a b c'), end='')
['ascript', 'a', 'b', 'c']
('__main__', 'ascript', 'demo doc')


For Python 2.5 and higher, you can also use the -m option to run a module:

>>> if sys.version_info < (2, 5):
...    print ('usage: pdb.py blah blah blah')
... else:
...    print_(system(join(bin, 'py')+' -m pdb'), end='')
... # doctest: +ELLIPSIS
usage: pdb.py ...

>>> print_(system(join(bin, 'py')+' -m pdb what'), end='')
Error: what does not exist


An additional argument can be passed to define which scripts to install and to provide script names. The argument is a dictionary mapping original script names to new script names.

>>> bin = tmpdir('bin2')
>>> scripts = zc.buildout.easy_install.scripts(
...     ['demo'], ws, sys.executable, bin, dict(demo='run'))

>>> if sys.platform == 'win32':
...     scripts == [os.path.join(bin, 'run.exe'),
...                 os.path.join(bin, 'run-script.py')]
... else:
...     scripts == [os.path.join(bin, 'run')]
True
>>> ls(bin)
-  run

>>> print_(system(os.path.join(bin, 'run')), end='')
3 1


#### Including extra paths in scripts

We can pass a keyword argument, extra paths, to cause additional paths to be included in the a generated script:

>>> foo = tmpdir('foo')
>>> scripts = zc.buildout.easy_install.scripts(
...    ['demo'], ws, sys.executable, bin, dict(demo='run'),
...    extra_paths=[foo])

>>> cat(bin, 'run') # doctest: +NORMALIZE_WHITESPACE
#!/usr/local/bin/python2.7
<BLANKLINE>
import sys
sys.path[0:0] = [
'/sample-install/demo-0.3-py2.4.egg',
'/sample-install/demoneeded-1.1-py2.4.egg',
'/foo',
]
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
sys.exit(eggrecipedemo.main())


#### Providing script arguments

An “argument” keyword argument can be used to pass arguments to an entry point. The value passed is a source string to be placed between the parentheses in the call:

>>> scripts = zc.buildout.easy_install.scripts(
...    ['demo'], ws, sys.executable, bin, dict(demo='run'),
...    arguments='1, 2')

>>> cat(bin, 'run') # doctest: +NORMALIZE_WHITESPACE
#!/usr/local/bin/python2.7
import sys
sys.path[0:0] = [
'/sample-install/demo-0.3-py2.4.egg',
'/sample-install/demoneeded-1.1-py2.4.egg',
]
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
sys.exit(eggrecipedemo.main(1, 2))


#### Passing initialization code

You can also pass script initialization code:

>>> scripts = zc.buildout.easy_install.scripts(
...    ['demo'], ws, sys.executable, bin, dict(demo='run'),
...    arguments='1, 2',
...    initialization='import os\nos.chdir("foo")')

>>> cat(bin, 'run') # doctest: +NORMALIZE_WHITESPACE
#!/usr/local/bin/python2.7
import sys
sys.path[0:0] = [
'/sample-install/demo-0.3-py2.4.egg',
'/sample-install/demoneeded-1.1-py2.4.egg',
]
<BLANKLINE>
import os
os.chdir("foo")
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
sys.exit(eggrecipedemo.main(1, 2))


#### Relative paths

Sometimes, you want to be able to move a buildout directory around and have scripts still work without having to rebuild them. We can control this using the relative_paths option to install. You need to pass a common base directory of the scripts and eggs:

>>> bo = tmpdir('bo')
>>> ba = tmpdir('ba')
>>> mkdir(bo, 'eggs')
>>> mkdir(bo, 'bin')
>>> mkdir(bo, 'other')

>>> ws = zc.buildout.easy_install.install(

>>> scripts = zc.buildout.easy_install.scripts(
...    ['demo'], ws, sys.executable, join(bo, 'bin'), dict(demo='run'),
...    extra_paths=[ba, join(bo, 'bar')],
...    interpreter='py',
...    relative_paths=bo)

>>> cat(bo, 'bin', 'run')
#!/usr/local/bin/python2.7
<BLANKLINE>
import os
<BLANKLINE>
join = os.path.join
base = os.path.dirname(os.path.abspath(os.path.realpath(__file__)))
base = os.path.dirname(base)
<BLANKLINE>
import sys
sys.path[0:0] = [
join(base, 'eggs/demo-0.3-pyN.N.egg'),
join(base, 'eggs/demoneeded-1.1-pyN.N.egg'),
'/ba',
join(base, 'bar'),
]
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
sys.exit(eggrecipedemo.main())


Note that the extra path we specified that was outside the directory passed as relative_paths wasn’t converted to a relative path.

Of course, running the script works:

>>> print_(system(join(bo, 'bin', 'run')), end='')
3 1


We specified an interpreter and its paths are adjusted too:

>>> cat(bo, 'bin', 'py')
#!/usr/local/bin/python2.7
<BLANKLINE>
import os
<BLANKLINE>
join = os.path.join
base = os.path.dirname(os.path.abspath(os.path.realpath(__file__)))
base = os.path.dirname(base)
<BLANKLINE>
import sys
<BLANKLINE>
sys.path[0:0] = [
join(base, 'eggs/demo-0.3-pyN.N.egg'),
join(base, 'eggs/demoneeded-1.1-pyN.N.egg'),
'/ba',
join(base, 'bar'),
]
<BLANKLINE>
_interactive = True
if len(sys.argv) > 1:
_options, _args = __import__("getopt").getopt(sys.argv[1:], 'ic:m:')
_interactive = False
for (_opt, _val) in _options:
if _opt == '-i':
_interactive = True
elif _opt == '-c':
exec(_val)
elif _opt == '-m':
sys.argv[1:] = _args
_args = []
__import__("runpy").run_module(
_val, {}, "__main__", alter_sys=True)
<BLANKLINE>
if _args:
sys.argv[:] = _args
__file__ = _args[0]
del _options, _args
__file__f = open(__file__)
__file__f.close(); del __file__f
<BLANKLINE>
if _interactive:
del _interactive
__import__("code").interact(banner="", local=globals())


#### Installing distutils-style scripts

Most python libraries use the console_scripts entry point nowadays. But several still have a scripts=['bin/something'] in their setup() call. Buildout also installs those:

>>> distdir = tmpdir('distutilsscriptdir')
>>> distbin = tmpdir('distutilsscriptbin')
>>> ws = zc.buildout.easy_install.install(
...     ['other'], distdir,
>>> scripts = zc.buildout.easy_install.scripts(
...     ['other'], ws, sys.executable, distbin)
>>> ls(distbin)
-  distutilsscript


It also works for zipped eggs:

>>> distdir2 = tmpdir('distutilsscriptdir2')
>>> distbin2 = tmpdir('distutilsscriptbin2')
>>> ws = zc.buildout.easy_install.install(
...     ['du_zipped'], distdir2,
>>> scripts = zc.buildout.easy_install.scripts(
...     ['du_zipped'], ws, sys.executable, distbin2)
>>> ls(distbin2)
-  distutilsscript


Distutils copies the script files verbatim, apart from a line at the top that looks like #!/usr/bin/python, which gets replaced by the actual python interpreter. Buildout does the same, but additionally also adds the sys.path like for the console_scripts:

>>> cat(distbin, 'distutilsscript')
#!/usr/local/bin/python2.7
<BLANKLINE>
import sys
sys.path[0:0] = [
'/distutilsscriptdir/other-1.0-pyN.N.egg',
]
<BLANKLINE>
<BLANKLINE>
import sys; sys.stdout.write("distutils!\n")


Due to the nature of distutils scripts, buildout cannot pass arguments as there’s no specific method to pass them to.

#### Handling custom build options for extensions provided in source distributions

Sometimes, we need to control how extension modules are built. The build function provides this level of control. It takes a single package specification, downloads a source distribution, and builds it with specified custom build options.

The build function takes 3 positional arguments:

spec
A package specification for a source distribution
dest
A destination directory
build_ext
A dictionary of options to be passed to the distutils build_ext command when building extensions.

It supports a number of optional keyword arguments:

a sequence of URLs, file names, or directories to look for links to distributions,
index

The URL of an index server, or almost any other valid URL. :)

If not specified, the Python Package Index, http://pypi.python.org/simple/, is used. You can specify an alternate index with this option. If you use the links option and if the links point to the needed distributions, then the index can be anything and will be largely ignored. In the examples, here, we’ll just point to an empty directory on our link server. This will make our examples run a little bit faster.

path
A list of additional directories to search for locally-installed distributions.
A boolean value indicating whether to search for new distributions when already-installed distributions meet the requirement. When this is true, the default, and when the destination directory is not None, then the install function will search for the newest distributions that satisfy the requirements.
versions
A dictionary mapping project names to version numbers to be used when selecting distributions. This can be used to specify a set of distribution versions independent of other requirements.

Our link server included a source distribution that includes a simple extension, extdemo.c:

#include <Python.h>
#include <extdemo.h>

static PyMethodDef methods[] = {};

PyMODINIT_FUNC
initextdemo(void)
{
PyObject *m;
m = Py_InitModule3("extdemo", methods, "");
#ifdef TWO
#else
#endif
}


The extension depends on a system-dependent include file, extdemo.h, that defines a constant, EXTDEMO, that is exposed by the extension.

We’ll add an include directory to our sample buildout and add the needed include file to it:

>>> mkdir('include')
>>> write('include', 'extdemo.h',
... """
... #define EXTDEMO 42
... """)


Now, we can use the build function to create an egg from the source distribution:

>>> zc.buildout.easy_install.build(
...   'extdemo', dest,
...   {'include-dirs': os.path.join(sample_buildout, 'include')},
['/sample-install/extdemo-1.4-py2.4-unix-i686.egg']


The function returns the list of eggs

Now if we look in our destination directory, we see we have an extdemo egg:

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demo-0.3-py2.4.egg
d  demoneeded-1.0-py2.4.egg
d  demoneeded-1.1-py2.4.egg
d  extdemo-1.4-py2.4-unix-i686.egg


Let’s update our link server with a new version of extdemo:

>>> update_extdemo()
<html><body>
<a href="bigdemo-0.1-py2.4.egg">bigdemo-0.1-py2.4.egg</a><br>
<a href="demo-0.1-py2.4.egg">demo-0.1-py2.4.egg</a><br>
<a href="demo-0.2-py2.4.egg">demo-0.2-py2.4.egg</a><br>
<a href="demo-0.3-py2.4.egg">demo-0.3-py2.4.egg</a><br>
<a href="demo-0.4c1-py2.4.egg">demo-0.4c1-py2.4.egg</a><br>
<a href="demoneeded-1.0.zip">demoneeded-1.0.zip</a><br>
<a href="demoneeded-1.1.zip">demoneeded-1.1.zip</a><br>
<a href="demoneeded-1.2c1.zip">demoneeded-1.2c1.zip</a><br>
<a href="du_zipped-1.0-pyN.N.egg">du_zipped-1.0-pyN.N.egg</a><br>
<a href="extdemo-1.4.zip">extdemo-1.4.zip</a><br>
<a href="extdemo-1.5.zip">extdemo-1.5.zip</a><br>
<a href="index/">index/</a><br>
<a href="other-1.0-py2.4.egg">other-1.0-py2.4.egg</a><br>
</body></html>


The easy_install caches information about servers to reduce network access. To see the update, we have to call the clear_index_cache function to clear the index cache:

>>> zc.buildout.easy_install.clear_index_cache()


If we run build with newest set to False, we won’t get an update:

>>> zc.buildout.easy_install.build(
...   'extdemo', dest,
...   {'include-dirs': os.path.join(sample_buildout, 'include')},
['/sample-install/extdemo-1.4-py2.4-linux-i686.egg']

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demo-0.3-py2.4.egg
d  demoneeded-1.0-py2.4.egg
d  demoneeded-1.1-py2.4.egg
d  extdemo-1.4-py2.4-unix-i686.egg


But if we run it with the default True setting for newest, then we’ll get an updated egg:

>>> zc.buildout.easy_install.build(
...   'extdemo', dest,
...   {'include-dirs': os.path.join(sample_buildout, 'include')},
['/sample-install/extdemo-1.5-py2.4-unix-i686.egg']

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demo-0.3-py2.4.egg
d  demoneeded-1.0-py2.4.egg
d  demoneeded-1.1-py2.4.egg
d  extdemo-1.4-py2.4-unix-i686.egg
d  extdemo-1.5-py2.4-unix-i686.egg


The versions option also influences the versions used. For example, if we specify a version for extdemo, then that will be used, even though it isn’t the newest. Let’s clean out the destination directory first:

>>> import os
>>> for name in os.listdir(dest):
...     remove(dest, name)

>>> zc.buildout.easy_install.build(
...   'extdemo', dest,
...   {'include-dirs': os.path.join(sample_buildout, 'include')},
...   versions=dict(extdemo='1.4'))
['/sample-install/extdemo-1.4-py2.4-unix-i686.egg']

>>> ls(dest)
d  extdemo-1.4-py2.4-unix-i686.egg


#### Handling custom build options for extensions in develop eggs

The develop function is similar to the build function, except that, rather than building an egg from a source directory containing a setup.py script.

The develop function takes 2 positional arguments:

setup
The path to a setup script, typically named “setup.py”, or a directory containing a setup.py script.
dest
The directory to install the egg link to

It supports some optional keyword argument:

build_ext
A dictionary of options to be passed to the distutils build_ext command when building extensions.

We have a local directory containing the extdemo source:

>>> ls(extdemo)
-  MANIFEST
-  MANIFEST.in
-  extdemo.c
-  setup.py


Now, we can use the develop function to create a develop egg from the source distribution:

>>> zc.buildout.easy_install.develop(
...   extdemo, dest,
...   {'include-dirs': os.path.join(sample_buildout, 'include')})


The name of the egg link created is returned.

Now if we look in our destination directory, we see we have an extdemo egg link:

>>> ls(dest)
d  extdemo-1.4-py2.4-unix-i686.egg


And that the source directory contains the compiled extension:

>>> contents = os.listdir(extdemo)
>>> bool([f for f in contents if f.endswith('.so') or f.endswith('.pyd')])
True


Normally, when distributions are installed, if any processing is needed, they are downloaded from the internet to a temporary directory and then installed from there. A download cache can be used to avoid the download step. This can be useful to reduce network access and to create source distributions of an entire buildout.

A download cache is specified by calling the download_cache function. The function always returns the previous setting. If no argument is passed, then the setting is unchanged. If an argument is passed, the download cache is set to the given path, which must point to an existing directory. Passing None clears the cache setting.

To see this work, we’ll create a directory and set it as the cache directory:

>>> cache = tmpdir('cache')


We’ll recreate our destination directory:

>>> remove(dest)
>>> dest = tmpdir('sample-install')


We’d like to see what is being fetched from the server, so we’ll enable server logging:

>>> _ = get(link_server+'enable_server_logging')
GET 200 /enable_server_logging


Now, if we install demo, and extdemo:

>>> ws = zc.buildout.easy_install.install(
...     ['demo==0.2'], dest,
GET 200 /
GET 404 /index/demo/
GET 200 /index/
GET 200 /demo-0.2-py2.4.egg
GET 404 /index/demoneeded/
GET 200 /demoneeded-1.1.zip

>>> zc.buildout.easy_install.build(
...   'extdemo', dest,
...   {'include-dirs': os.path.join(sample_buildout, 'include')},
GET 404 /index/extdemo/
GET 200 /extdemo-1.5.zip
['/sample-install/extdemo-1.5-py2.4-linux-i686.egg']


Not only will we get eggs in our destination directory:

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demoneeded-1.1-py2.4.egg
d  extdemo-1.5-py2.4-linux-i686.egg


But we’ll get distributions in the cache directory:

>>> ls(cache)
-  demo-0.2-py2.4.egg
-  demoneeded-1.1.zip
-  extdemo-1.5.zip


The cache directory contains uninstalled distributions, such as zipped eggs or source distributions.

Let’s recreate our destination directory and clear the index cache:

>>> remove(dest)
>>> dest = tmpdir('sample-install')
>>> zc.buildout.easy_install.clear_index_cache()


Now when we install the distributions:

>>> ws = zc.buildout.easy_install.install(
...     ['demo==0.2'], dest,
GET 200 /
GET 404 /index/demo/
GET 200 /index/
GET 404 /index/demoneeded/

>>> zc.buildout.easy_install.build(
...   'extdemo', dest,
...   {'include-dirs': os.path.join(sample_buildout, 'include')},
GET 404 /index/extdemo/
['/sample-install/extdemo-1.5-py2.4-linux-i686.egg']

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demoneeded-1.1-py2.4.egg
d  extdemo-1.5-py2.4-linux-i686.egg


>>> ws = zc.buildout.easy_install.install(
...     ['demo'], dest,
GET 200 /demo-0.3-py2.4.egg


A download cache can be used as the basis of application source releases. In an application source release, we want to distribute an application that can be built without making any network accesses. In this case, we distribute a download cache and tell the easy_install module to install from the download cache only, without making network accesses. The install_from_cache function can be used to signal that packages should be installed only from the download cache. The function always returns the previous setting. Calling it with no arguments returns the current setting without changing it:

>>> zc.buildout.easy_install.install_from_cache()
False


Calling it with a boolean value changes the setting and returns the previous setting:

>>> zc.buildout.easy_install.install_from_cache(True)
False


Let’s remove demo-0.3-py2.4.egg from the cache, clear the index cache, recreate the destination directory, and reinstall demo:

>>> for  f in os.listdir(cache):
...     if f.startswith('demo-0.3-'):
...         remove(cache, f)

>>> zc.buildout.easy_install.clear_index_cache()
>>> remove(dest)
>>> dest = tmpdir('sample-install')

>>> ws = zc.buildout.easy_install.install(
...     ['demo'], dest,

>>> ls(dest)
d  demo-0.2-py2.4.egg
d  demoneeded-1.1-py2.4.egg


## Change History

### 2.0.0a6 (2013-01-11)

Changed the configuratiion file format:

• Relative indentation in option values is retained if the first line is blank. (IOW, if the non-blank text is on the continuation lines.) As in:

[mysection]
tree =
/root
branch


In such cases, internal blank lines are also retained.

• The configuration syntax is more tightly defined, allowing fewer syntax definitions.

Buildout 1 configuration files were parsed with the Python ConfigParser module. The ConfigParser module’s format is poorly documented and wildly flexible. For example:

• Any characters other than left square brackets were allowed in section names.
• Arbitrary text was allowed and ignored after the closing bracket on section header lines.
• Any characters other than equal signs or colons were allowed in an option name.
• Configuration options could be spelled as RFC 822 mail headers (using a colon, rather than an equal sign).
• Comments could begin with “rem”.
• Semicolons could be used to start inline comments, but only if preceeded by a whitespace character.

### 2.0.0a5 (2012-12-01)

• Buildout now prefers final releases by default (buildout:prefer-final now defaults to true, rather than false.)

However, if buildout is bootstrapped with a non-final release, it won’t downgrade itself to a final release.

• Versions in versions sections can now be simple constraints, like >=2.0dev in addition to being simple versions.

Buildout 2 leverages this to make sure it uses zc.recipe.egg>=2.0.0a3, which mainly matters for Python 3.

### 2.0.0a4 (2012-11-19)

Tweaked PyPi page.

### 2.0.0a3 (2012-11-19)

New features:

• The buildout init command now accepts distribution requirements and paths to set up a custom interpreter part that has the distributions or parts in the path. For example:

python bootstrap.py init BeautifulSoup

• Added buildout:socket-timout option so that socket timeout can be configured both from command line and from config files. (gotcha)

• Distutils-style scripts are also installed now (for instance pyflakes’ and docutils’ scripts). https://bugs.launchpad.net/zc.buildout/+bug/422724

• Switched development location to github.com/buildout.

• Avoid sorting the working set and requirements when it won’t be logged. When profiling a simple buildout with 10 parts with identical and large working sets, this resulted in a decrease of run time from 93.411 to 15.068 seconds, about a 6 fold improvement. To see the benefit be sure to run without any increase in verbosity (“-v” option). (rossp)

• Introduce a cache for the expensive buildout._dir_hash function.

• Remove duplicate path from script’s sys.path setup.

• Make sure to download extended configuration files only once per buildout run even if they are referenced multiple times (patch by Rafael Monnerat).

• Removed any traces of the implementation of extended-by. Raise a UserError if the option is encountered instead of ignoring it, though.

Bugs fixed:

### 1.4.4 (2010-08-20)

The 1.4.4 release is a release for people who encounter trouble with the 1.5 line. By switching to the associated bootstrap script you can stay on 1.4.4 until you are ready to migrate.

### 1.4.3 (2009-12-10)

Bugs fixed:

• Using pre-detected setuptools version for easy_installing tgz files. This prevents a recursion error when easy_installing an upgraded “distribute” tgz. Note that setuptools did not have this recursion problem solely because it was packaged as an .egg, which does not have to go through the easy_install step.

### 1.4.2 (2009-11-01)

New Feature:

• Added a –distribute option to the bootstrap script, in order to use Distribute rather than Setuptools. By default, Setuptools is used.

Bugs fixed:

• While checking for new versions of setuptools and buildout itself, compare requirement locations instead of requirement objects.
• Incrementing didn’t work properly when extending multiple files. https://bugs.launchpad.net/zc.buildout/+bug/421022
• The download API computed MD5 checksums of text files wrong on Windows.

### 1.4.1 (2009-08-27)

New Feature:

• Added a debug built-in recipe to make writing some tests easier.

Bugs fixed:

• (introduced in 1.4.0) option incrementing (-=) and decrementing (-=) didn’t work in the buildout section. https://bugs.launchpad.net/zc.buildout/+bug/420463
• Option incrementing and decrementing didn’t work for options specified on the command line.
• Scripts generated with relative-paths enabled couldn’t be symbolically linked to other locations and still work.
• Scripts run using generated interpreters didn’t have __file__ set correctly.
• The standard Python -m option didn’t work for custom interpreters.

### 1.4.0 (2009-08-26)

• When doing variable substitutions, you can omit the section name to refer to a variable in the same section (e.g. ${:foo}). • When doing variable substitution, you can use the special option, _buildout_section_name_ to get the section name. This is most handy for getting the current section name (e.g.${:_buildout_section_name_}).
• A new special option, < allows sections to be used as macros.
• Added annotate command for annotated sections. Displays sections key-value pairs along with the value origin.
• Used the download API to allow caching of base configurations (specified by the buildout section’s ‘extends’ option).

### 1.3.1 (2009-08-12)

• Bug fixed: extras were ignored in some cases when versions were specified.

### 1.3.0 (2009-06-22)

• Better Windows compatibility in test infrastructure.
• Now the bootstrap.py has an optional –version argument, that can be used to force buildout version to use.
• zc.buildout.testing.buildoutSetUp installs a new handler in the python root logging facility. This handler is now removed during tear down as it might disturb other packages reusing buildout’s testing infrastructure.
• fixed usage of ‘relative_paths’ keyword parameter on Windows
• Fixed bug: when the relative paths option was used, relative paths could be inserted into sys.path if a relative path was used to run the generated script.

### 1.2.1 (2009-03-18)

• Refactored generation of relative egg paths to generate simpler code.

### 1.2.0 (2009-03-17)

• Added a relative_paths option to zc.buildout.easy_install.script to generate egg paths relative to the script they’re used in.

### 1.1.2 (2009-03-16)

• Added Python 2.6 support. Removed Python 2.3 support.

• Fixed remaining deprecation warnings under Python 2.6, both when running our tests and when using the package.

• Switched from using os.popen* to subprocess.Popen, to avoid a deprecation warning in Python 2.6. See:

http://docs.python.org/library/subprocess.html#replacing-os-popen-os-popen2-os-popen3

• Made sure the ‘redo_pyc’ function and the doctest checkers work with Python executable paths containing spaces.

• Expand shell patterns when processing the list of paths in develop, e.g:

[buildout]
develop = ./local-checkouts/*

• Conditionally import and use hashlib.md5 when it’s available instead of md5 module, which is deprecated in Python 2.6.

• Added Jython support for bootstrap, development bootstrap and buildout support on Jython

• Fixed a bug that would cause buildout to break while computing a directory hash if it found a broken symlink (Launchpad #250573)

### 1.1.1 (2008-07-28)

• Fixed a bug that caused buildouts to fail when variable substitutions are used to name standard directories, as in:

[buildout]
eggs-directory = ${buildout:directory}/develop-eggs  ### 1.1.0 (2008-07-19) • Added a buildout-level unzip option tp change the default policy for unzipping zip-safe eggs. • Tracebacks are now printed for internal errors (as opposed to user errors) even without the -D option. • pyc and pyo files are regenerated for installed eggs so that the stored path in code objects matches the the install location. ### 1.0.6 (2008-06-13) ### 1.0.5 (2008-06-10) • Fixed wrong split when using the += and -= syntax (mustapha) ### 1.0.4 (2008-06-10) • Added the allow-hosts option (tarek) • Quote the ‘executable’ argument when trying to detect the python version using popen4. (sidnei) • Quote the ‘spec’ argument, as in the case of installing an egg from the buildout-cache, if the filename contains spaces it would fail (sidnei) • Extended configuration syntax to allow -= and += operators (malthe, mustapha). ### 1.0.3 (2008-06-01) • fix for “””AttributeError: Buildout instance has no attribute ‘_logger’””” by providing reasonable defaults within the Buildout constructor. (patch by Gottfried Ganssauge) (ajung) ### 1.0.2 (2008-05-13) • More fixes for Windows. A quoted sh-bang is now used on Windows to make the .exe files work with a Python executable in ‘program files’. • Added “-t <timeout_in_seconds>” option for specifying the socket timeout. (ajung) ### 1.0.1 (2008-04-02) • Made easy_install.py’s _get_version accept non-final releases of Python, like 2.4.4c0. (hannosch) • Applied various patches for Windows (patch by Gottfried Ganssauge). (ajung) • Applied patch fixing rmtree issues on Windows (patch by Gottfried Ganssauge). (ajung) ### 1.0.0 (2008-01-13) • Added a French translation of the buildout tutorial. ### 1.0.0b31 (2007-11-01) #### Feature Changes • Added a configuration option that allows buildouts to ignore dependency_links metadata specified in setup. By default dependency_links in setup are used in addition to buildout specified find-links. This can make it hard to control where eggs come from. Here’s how to tell buildout to ignore URLs in dependency_links: [buildout] use-dependency-links = false  By default use-dependency-links is true, which matches the behavior of previous versions of buildout. • Added a configuration option that causes buildout to error if a version is picked. This is a nice safety belt when fixing all versions is intended, especially when creating releases. #### Bugs Fixed • 151820: Develop failed if the setup.py script imported modules in the distribution directory. • Verbose logging of the develop command was omitting detailed output. • The setup command wasn’t documented. • The setup command failed if run in a directory without specifying a configuration file. • The setup command raised a stupid exception if run without arguments. • When using a local find links or index, distributions weren’t copied to the download cache. • When installing from source releases, a version specification (via a buildout versions section) for setuptools was ignored when deciding which setuptools to use to build an egg from the source release. ### 1.0.0b30 (2007-08-20) ### Feature Changes • Changed the default policy back to what it was to avoid breakage in existing buildouts. Use: [buildout] prefer-final = true  to get the new policy. The new policy will go into effect in buildout 2. ### 1.0.0b29 (2007-08-20) #### Feature Changes • Now, final distributions are prefered over non-final versions. If both final and non-final versions satisfy a requirement, then the final version will be used even if it is older. The normal way to override this for specific packages is to specifically require a non-final version, either specifically or via a lower bound. • There is a buildout prefer-final version that can be used with a value of “false”: prefer-final = false  To prefer newer versions, regardless of whether or not they are final, buildout-wide. • The new simple Python index, http://cheeseshop.python.org/simple, is used as the default index. This will provide better performance than the human package index interface, http://pypi.python.org/pypi. More importantly, it lists hidden distributions, so buildouts with fixed distribution versions will be able to find old distributions even if the distributions have been hidden in the human PyPI interface. #### Bugs Fixed • 126441: Look for default.cfg in the right place on Windows. ### 1.0.0b28 (2007-07-05) ### Bugs Fixed • When requiring a specific version, buildout looked for new versions even if that single version was already installed. ### 1.0.0b27 (2007-06-20) ### Bugs Fixed • Scripts were generated incorrectly on Windows. This included the buildout script itself, making buildout completely unusable. ### 1.0.0b26 (2007-06-19) ### Feature Changes • Thanks to recent fixes in setuptools, I was able to change buildout to use find-link and index information when searching extensions. Sadly, this work, especially the timing, was motivated my the need to use alternate indexes due to performance problems in the cheese shop (http://www.python.org/pypi/). I really home we can address these performance problems soon. ### 1.0.0b25 (2007-05-31) #### Feature Changes • buildout now changes to the buildout directory before running recipe install and update methods. • Added a new init command for creating a new buildout. This creates an empty configuration file and then bootstraps. • Except when using the new init command, it is now an error to run buildout without a configuration file. • In verbose mode, when adding distributions to fulful requirements of already-added distributions, we now show why the new distributions are being added. • Changed the logging format to exclude the logger name for the buildout logger. This reduces noise in the output. • Clean up lots of messages, adding missing periods and adding quotes around requirement strings and file paths. #### Bugs Fixed • 114614: Buildouts could take a very long time if there were dependency problems in large sets of pathologically interdependent packages. • 59270: Buggy recipes can cause failures in later recipes via chdir • 61890: file:// urls don’t seem to work in find-links setuptools requires that file urls that point to directories must end in a “/”. Added a workaround. • 75607: buildout should not run if it creates an empty buildout.cfg ### 1.0.0b24 (2007-05-09) #### Feature Changes • Improved error reporting by showing which packages require other packages that can’t be found or that cause version conflicts. • Added an API for use by recipe writers to clean up created files when recipe errors occur. • Log installed scripts. #### Bugs Fixed • 92891: bootstrap crashes with recipe option in buildout section. • 113085: Buildout exited with a zero exist status when internal errors occured. ### 1.0.0b23 (2007-03-19) #### Feature Changes • Added support for download caches. A buildout can specify a cache for distribution downloads. The cache can be shared among buildouts to reduce network access and to support creating source distributions for applications allowing install without network access. • Log scripts created, as suggested in: https://bugs.launchpad.net/zc.buildout/+bug/71353 #### Bugs Fixed • It wasn’t possible to give options on the command line for sections not defined in a configuration file. ### 1.0.0b22 (2007-03-15) ### Feature Changes • Improved error reporting and debugging support: • Added “logical tracebacks” that show functionally what the buildout was doing when an error occurs. Don’t show a Python traceback unless the -D option is used. • Added a -D option that causes the buildout to print a traceback and start the pdb post-mortem debugger when an error occurs. • Warnings are printed for unused options in the buildout section and installed-part sections. This should make it easier to catch option misspellings. • Changed the way the installed database (.installed.cfg) is handled to avoid database corruption when a user breaks out of a buildout with control-c. • Don’t save an installed database if there are no installed parts or develop egg links. ### 1.0.0b21 (2007-03-06) ### Feature Changes • Added support for repeatable buildouts by allowing egg versions to be specified in a versions section. • The easy_install module install and build functions now accept a versions argument that supplied to mapping from project name to version numbers. This can be used to fix version numbers for required distributions and their depenencies. When a version isn’t fixed, using either a versions option or using a fixed version number in a requirement, then a debug log message is emitted indicating the version picked. This is useful for setting versions options. A default_versions function can be used to set a default value for this option. • Adjusted the output for verbosity levels. Using a single -v option no longer causes voluminous setuptools output. Uisng -vv and -vvv now triggers extra setuptools output. • Added a remove testing helper function that removes files or directories. ### 1.0.0b20 (2007-02-08) #### Feature Changes • Added a buildout newest option, to control whether the newest distributions should be sought to meet requirements. This might also provide a hint to recipes that don’t deal with distributions. For example, a recipe that manages subversion checkouts might not update a checkout if newest is set to “false”. • Added a newest keyword parameter to the zc.buildout.easy_install.install and zc.buildout.easy_install.build functions to control whether the newest distributions that meed given requirements should be sought. If a false value is provided for this parameter and already installed eggs meet the given requirements, then no attempt will be made to search for newer distributions. • The recipe-testing support setUp function now adds the name buildout to the test namespace with a value that is the path to the buildout script in the sample buildout. This allows tests to use >>> print system(buildout),  rather than: >>> print system(join('bin', 'buildout')),  #### Bugs Fixed • Paths returned from update methods replaced lists of installed files rather than augmenting them. ### 1.0.0b19 (2007-01-24) ### Bugs Fixed • Explicitly specifying a Python executable failed if the output of running Python with the -V option included a 2-digit (rather than a 3-digit) version number. ### 1.0.0b18 (2007-01-22) #### Feature Changes • Added documentation for some previously undocumented features of the easy_install APIs. • By popular demand, added a -o command-line option that is a short hand for the assignment buildout:offline=true. #### Bugs Fixed • When deciding whether recipe develop eggs had changed, buildout incorrectly considered files in .svn and CVS directories. ### 1.0.0b17 (2006-12-07) #### Feature Changes • Configuration files can now be loaded from URLs. #### Bugs Fixed ### 1.0.0b16 (2006-12-07) #### Feature Changes • A new command-line argument, -U, suppresses reading user defaults. • You can now suppress use of an installed-part database (e.g. .installed.cfg) by sprifying an empty value for the buildout installed option. #### Bugs Fixed • When the install command is used with a list of parts, only those parts are supposed to be installed, but the buildout was also building parts that those parts depended on. ### 1.0.0b15 (2006-12-06) ### Bugs Fixed • Uninstall recipes weren’t loaded correctly in cases where no parts in the (new) configuration used the recipe egg. ### 1.0.0b14 (2006-12-05) #### Feature Changes • Added uninstall recipes for dealing with complex uninstallation scenarios. #### Bugs Fixed • Automatic upgrades weren’t performed on Windows due to a bug that caused buildout to incorrectly determine that it wasn’t running locally in a buildout. • Fixed some spurious test failures on Windows. ### 1.0.0b13 (2006-12-04) #### Feature Changes • Variable substitutions now reflect option data written by recipes. • A part referenced by a part in a parts list is now added to the parts list before the referencing part. This means that you can omit parts from the parts list if they are referenced by other parts. • Added a develop function to the easy_install module to aid in creating develop eggs with custom build_ext options. • The build and develop functions in the easy_install module now return the path of the egg or egg link created. • Removed the limitation that parts named in the install command can only name configured parts. • Removed support ConfigParser-style variable substitutions (e.g. %(foo)s). Only the string-template style of variable (e.g.${section:option}) substitutions will be supported. Supporting both violates “there’s only one way to do it”.
• Deprecated the buildout-section extendedBy option.

#### Bugs Fixed

• We treat setuptools as a dependency of any distribution that (declares that it) uses namespace packages, whether it declares setuptools as a dependency or not. This wasn’t working for eggs intalled by virtue of being dependencies.

### Feature Changes

• Added an initialization argument to the zc.buildout.easy_install.scripts function to include initialization code in generated scripts.

### Bugs Fixed

67737
Verbose and quite output options caused errors when the develop buildout option was used to create develop eggs.
67871
Installation failed if the source was a (local) unzipped egg.
67873
There was an error in producing an error message when part names passed to the install command weren’t included in the configuration.

### 1.0.0b10 (2006-10-16)

#### Feature Changes

• Renamed the runsetup command to setup. (The old name still works.)
• Added a recipe update method. Now install is only called when a part is installed for the first time, or after an uninstall. Otherwise, update is called. For backward compatibility, recipes that don’t define update methiods are still supported.
• If a distribution defines namespace packages but fails to declare setuptools as one of its dependencies, we now treat setuptools as an implicit dependency. We generate a warning if the distribution is a develop egg.
• You can now create develop eggs for setup scripts that don’t use setuptools.

#### Bugs Fixed

• Egg links weren’t removed when corresponding entries were removed from develop sections.
• Running a non-local buildout command (one not installed in the buildout) ket to a hang if there were new versions of buildout or setuptools were available. Now we issue a warning and don’t upgrade.
• When installing zip-safe eggs from local directories, the eggs were moved, rather than copied, removing them from the source directory.

### Bugs Fixed

Non-zip-safe eggs were not unzipped when they were installed.

### Bugs Fixed

• Installing source distributions failed when using alternate Python versions (depending on the versions of Python used.)
• Installing eggs wasn’t handled as efficiently as possible due to a bug in egg URL parsing.
• Fixed a bug in runsetup that caused setup scripts that introspected __file__ to fail.

### 1.0.0b7

Added a documented testing framework for use by recipes. Refactored the buildout tests to use it.

Added a runsetup command run a setup script. This is handy if, like me, you don’t install setuptools in your system Python.

### 1.0.0b6

Fixed https://launchpad.net/products/zc.buildout/+bug/60582 Use of extension options caused bootstrapping to fail if the eggs directory didn’t already exist. We no longer use extensions for bootstrapping. There really isn’t any reason to anyway.

### 1.0.0b5

Refactored to do more work in buildout and less work in easy_install. This makes things go a little faster, makes errors a little easier to handle, and allows extensions (like the sftp extension) to influence more of the process. This was done to fix a problem in using the sftp support.

### 1.0.0b4

• Added an experimental extensions mechanism, mainly to support adding sftp support to buildouts that need it.
• Fixed buildout self-updating on Windows.

### 1.0.0b3

• Added a help option (-h, –help)

• Increased the default level of verbosity.

• Buildouts now automatically update themselves to new versions of buildout and setuptools.

• Added a recipe API for generating user errors.

• No-longer generate a py_zc.buildout script.

• Fixed some bugs in variable substitutions.

The characters “-”, “.” and ” “, weren’t allowed in section or option names.

Substitutions with invalid names were ignored, which caused missleading failures downstream.

• Improved error handling. No longer show tracebacks for user errors.

• Now require a recipe option (and therefore a section) for every part.

• Expanded the easy_install module API to:

• Allow extra paths to be provided
• Specify explicit entry points
• Specify entry-point arguments

### 1.0.0b2

Added support for specifying some build_ext options when installing eggs from source distributions.

### 1.0.0b1

• Changed the bootstrapping code to only install setuptools and buildout. The bootstrap code no-longer runs the buildout itself. This was to fix a bug that caused parts to be recreated unnecessarily because the recipe signature in the initial buildout reflected temporary locations for setuptools and buildout.
• Now create a minimal setup.py if it doesn’t exist and issue a warning that it is being created.
• Fixed bug in saving installed configuration data. %’s and extra spaces weren’t quoted.

### 1.0.0a1

Initial public version