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System for managing development buildouts

Project description

The Buildout project provides support for creating applications, especially Python applications. It provides tools for assembling applications from multiple parts, Python or otherwise. An application may actually contain multiple programs, processes, and configuration settings.

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”.

To get a feel for some of the things you might use buildouts for, see the Buildout examples.

To lean more about using buildouts, see Detailed Documentation.

Recipes

Existing recipes include:

zc.recipe.egg
The egg recipe installes one or more eggs, with their dependencies. It installs their console-script entry points with the needed eggs included in their paths.
zc.recipe.testrunner
The testrunner egg installs creates a test runner script for one or more eggs.
zc.recipe.zope3checkout
The zope3checkout recipe installs a Zope 3 checkout into a buildout.
zc.recipe.zope3instance
The zope3instance recipe sets up a Zope 3 instance.
zc.recipe.filestorage
The filestorage recipe sets up a ZODB file storage for use in a Zope 3 instance creayed by the zope3instance recipe.

Buildout examples

Here are a few examples of what you can do with buildouts. We’ll present these as a set of use cases.

Try out an egg

Sometimes you want to try an egg (or eggs) that someone has released. You’d like to get a Python interpreter that lets you try things interactively or run sample scripts without having to do path manipulations. If you can and don’t mind modifying your Python installation, you could use easy_install, otherwise, you could create a directory somewhere and create a buildout.cfg file in that directory containing:

[buildout]
parts = mypython

[mypython]
recipe = zc.recipe.egg
interpreter = mypython
eggs = theegg

where theegg is the name of the egg you want to try out.

Run buildout in this directory. It will create a bin subdirectory that includes a mypython script. If you run mypython without any arguments you’ll get an interactive interpreter with the egg in the path. If you run it with a script and script arguments, the script will run with the egg in its path. Of course, you can specify as many eggs as you want in the eggs option.

If the egg provides any scripts (console_scripts entry points), those will be installed in your bin directory too.

Work on a package

I often work on packages that are managed separately. They don’t have scripts to be installed, but I want to be able to run their tests using the zope.testing test runner. In this kind of application, the program to be instaleld is the test runner. A good example of this is zc.ngi.

Here I have a subversion project for the zc.ngi package. The software is in the src directory. The configuration file is very simple:

[buildout]
develop = .
parts = test

[test]
recipe = zc.recipe.testrunner
eggs = zc.ngi

I use the develop option to create a develop egg based on the current directory. I request a test script named “test” using the zc.recipe.testrunner recipe. In the section for the test script, I specify that I want to run the tests in the zc.ngi package.

When I check out this project into a new sandbox, I run bootstrap.py to get setuptools and zc.buildout and create bin/buildout. I run bin/buildout, which installs the test script, bin/test, which I can then use to run the tests.

This is probably the most common type of buildout.

The zc.buildout project is a slightly more complex example of this type of buildout.

Install egg-based scripts

A variation of the Try out an egg use case is to install scripts into your ~/bin directory (on Unix, of course). My ~/bin directory is a buildout with a configuration file that looks like:

[buildout]
parts = foo bar
bin-directory = .

[foo]
...

whwre foo and bar are packages with scripts that I want available. As I need new scripts, I can add additional sections. The bin-directory option specified that scripts should be installed into the current directory.

Multi-program multi-machine systems

Using an older prototype version of the buildout, we’ve build a number of systems involving multiple programs, databases, and machines. One typical example consists of:

  • Multiple Zope instances
  • Multiple ZEO servers
  • An LDAP server
  • Cache-invalidation and Mail delivery servers
  • Dozens of add-on packages
  • Multiple test runners
  • Multiple deployment modes, including dev, stage, and prod, with prod deployment over multiple servers

Parts installed include:

  • Application software installs, including Zope, ZEO and LDAP software
  • Add-on packages
  • Bundles of configuration that define Zope, ZEO and LDAP instances
  • Utility scripts such as test runners, server-control scripts, cron jobs.

Questions and Bug Reporting

Please send questions and comments to the distutils SIG mailing list.

Report bugs using the zc.buildout Launchpad Bug Tracker.

Status

The buildout system is under active development. Some near term priorities include:

  • Fixing bugs
  • Making buildouts more repeatable
  • Adding support for making distributions from buildouts
  • Better error reporing
  • Handling of egg extras
  • More recipes

Change History

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.

1.0.0b12 (2006-10-24)

Feature Changes

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

1.0.0b11 (2006-10-24)

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 zc.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.

1.0.0b9 (2006-10-02)

Bugs Fixed

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

1.0.0b8 (2006-10-01)

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 zc.buildout and setuptools.

  • Added Windows support.

  • 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 zc.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 zc.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

Detailed 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 setuptools 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 buildoput 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 setuptools 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')
-  setuptools-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.buildout = buildout
...         self.name = name
...         self.options = 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 [1]:

  • 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 ajusting 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 relevent 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.

We need to provide packaging information so that our recipe can be installed as a develop egg. The minimum information we need to specify [2] 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 setuptools 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),
buildout: Develop: /sample-buildout/recipes
buildout: 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]
installed_develop_eggs = /sample-buildout/develop-eggs/recipes.egg-link
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),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling data-dir
buildout: 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),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling data-dir
buildout: 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 UserError causes the buildout to print the error and exit without printing a traceback. In the sample above, of someone gives a non-existant 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),
buildout: Develop: /sample-buildout/recipes
data-dir: Cannot create /xxx/mydata. /xxx is not a directory.
Error: Invalid Path

Configuration file syntax

As mentioned earlier, buildout configuration files use the format defined by the Python ConfigParser module with extensions. The extensions are:

  • option names are case sensitive
  • option values can ue a substitution syntax, described below, to refer to option values in specific sections.

The ConfigParser syntax is very flexible. Section names can contain any characters other than newlines and right square braces (“]”). Option names can contain any characters other than newlines, colons, and equal signs, can not start with a space, and don’t include trailing spaces.

It is likely that, in the future, some characters will be given special buildout-defined meanings. This is already true of the characters “:”, “$”, “%”, “(“, and “)”. For now, it is a good idea to keep section and option names simple, sticking to alphanumeric characters, hyphens, and periods.

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',
... """
... class Debug:
...
...     def __init__(self, buildout, name, options):
...         self.buildout = buildout
...         self.name = name
...         self.options = options
...
...     def install(self):
...         items = self.options.items()
...         items.sort()
...         for option, value in items:
...             print 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
... """)

In this example, we’ve used ConfigParser substitutions for file2 and file3. This type of substitution uses Python string format syntax. Valid names are options in the same section and options defined in the DEFAULT section.

We used a string-template substitution for file1. 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),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling data-dir
buildout: Installing data-dir
data-dir: Creating directory mydata
buildout: 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),
buildout: Develop: /sample-buildout/recipes
buildout: Updating data-dir
buildout: 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.

Automatic part selection and ordering

When a section with a recipe is refered 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),
buildout: Develop: /sample-buildout/recipes
buildout: Updating data-dir
buildout: Updating 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
... File 2 = ${debug:File 1}/log
...
... [data-dir]
... recipe = recipes:mkdir
... path = mydata
... """)

It will still be treated as a part:

>>> print system(buildout),
buildout: Develop: /sample-buildout/recipes
buildout: Updating data-dir
buildout: Updating 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
...

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),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: Uninstalling data-dir
buildout: 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),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: 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.

User defaults

If the file $HOME/.buildout/defaults.cfg, exists, it is read before reading the configuration file. ($HOME is the value of the HOME environment variable. The ‘/’ is replaced by the operating system file delimiter.)

>>> home = tmpdir('home')
>>> mkdir(home, '.buildout')
>>> write(home, '.buildout', 'default.cfg',
... """
... [debug]
... op1 = 1
... op7 = 7
... """)
>>> os.environ['HOME'] = home
>>> print system(buildout),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: 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'),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: Installing debug
name base
op buildout
op1 b1 1
op2 b2 2
op3 b2 3
op4 b3 4
op5 b3base 5
recipe recipes:debug
>>> del os.environ['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),
name base
op1 b1 1
op2 b2 2
op3 b2 3
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',
... """
... class Service:
...
...     def __init__(self, buildout, name, options):
...         self.buildout = buildout
...         self.name = name
...         self.options = options
...
...     def install(self):
...         print "chkconfig --add %s" % self.options['script']
...         return ()
...
...     def update(self):
...         pass
...
...
... def uninstall_service(name, options):
...     print "chkconfig --del %s" % 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)
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: Installing service
chkconfig --add /path/to/script
<BLANKLINE>

The service has been installed. If the buildout is run again with no changes, the serivce shouldn’t be changed.

>>> print system(buildout)
buildout: Develop: /sample-buildout/recipes
buildout: Updating service
<BLANKLINE>

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)
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling service
buildout: Running uninstall recipe
chkconfig --del /path/to/script
buildout: Installing service
chkconfig --add /path/to/a/different/script
<BLANKLINE>

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)
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling service
buildout: Running uninstall recipe
chkconfig --del /path/to/a/different/script
buildout: Installing debug
recipe recipes:debug
<BLANKLINE>

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
... def backup_directory(name, options):
...     path = options['path']
...     size = len(os.listdir(path))
...     print "backing up directory %s of size %s" % (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)
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: Installing dir
dir: Creating directory my_directory
buildout: Installing debug
recipe recipes:debug
<BLANKLINE>

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)
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling dir
buildout: Running uninstall recipe
backing up directory /sample-buildout/my_directory of size 0
buildout: Updating debug
recipe recipes:debug
<BLANKLINE>

Now we will return the registeration 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 [-h] [-c file] [-q] [-v] [-U] [assignments] [command [command arguments]]

The -h (or –help) option causes basic usage information to be printed. If this option is used, then all other options are ignored.

The -c option can be used to specify a configuration file, rather than buildout.cfg in the current directory.

The -q and -v decrement and 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.

The -U option suppresses reading user defaults.

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'),
buildout: Develop: /sample-buildout/recipes
buildout: 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'),
buildout: Develop: /sample-buildout/recipes
buildout: 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),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: Installing debug
recipe recipes:debug
buildout: Installing d1
d1: Creating directory d1
buildout: Installing d2
d2: Creating directory d2
buildout: 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  develop-eggs
d  eggs
d  parts
d  recipes
>>> cat(sample_buildout, '.installed.cfg')
[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'),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling d3
buildout: Installing d3
d3: Creating directory data3
buildout: 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  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')
[buildout]
installed_develop_eggs = /sample-buildout/develop-eggs/recipes.egg-link
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),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling d2
buildout: Uninstalling d1
buildout: Uninstalling debug
buildout: Installing debug
recipe recipes:debug
x 1
buildout: Installing d2
d2: Creating directory data2
buildout: Updating d3
buildout: 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  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 =
... develop-eggs-directory = %(developbasket)s
... eggs-directory = %(basket)s
... bin-directory = %(scripts)s
... parts-directory = %(work)s
... """ % dict(
...    developbasket = os.path.join(alt, 'developbasket'),
...    basket = os.path.join(alt, 'basket'),
...    scripts = os.path.join(alt, 'scripts'),
...    work = os.path.join(alt, 'work'),
... ))
>>> print system(buildout),
buildout: Creating directory /sample-alt/scripts
buildout: Creating directory /sample-alt/work
buildout: Creating directory /sample-alt/basket
buildout: Creating directory /sample-alt/developbasket
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling d4
buildout: Uninstalling d3
buildout: Uninstalling d2
buildout: Uninstalling debug
>>> ls(alt)
d  basket
d  developbasket
d  scripts
d  work
>>> ls(alt, 'developbasket')
-  recipes.egg-link

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),
buildout: Creating directory /sample-alt/bin
buildout: Creating directory /sample-alt/parts
buildout: Creating directory /sample-alt/eggs
buildout: Creating directory /sample-alt/develop-eggs
buildout: Develop: /sample-buildout/recipes
>>> ls(alt)
-  .installed.cfg
d  bin
d  develop-eggs
d  eggs
d  parts
>>> ls(alt, 'develop-eggs')
-  recipes.egg-link

Logging control

Three buildout options are used to control logging:

log-level
specifies the log level
verbosity
adjusts the log level
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),
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+' -v'),
zc.buildout.easy_install: Installing ['zc.buildout', 'setuptools']
zc.buildout.easy_install: We have a develop egg for zc.buildout
zc.buildout.easy_install: We have the best distribution that satisfies
setuptools
<BLANKLINE>
Configuration data:
[buildout]
bin-directory = /sample-buildout/bin
develop-eggs-directory = /sample-buildout/develop-eggs
directory = /sample-buildout
eggs-directory = /sample-buildout/eggs
executable = /usr/local/bin/python2.3
installed = /sample-buildout/.installed.cfg
log-format = %(name)s: %(message)s
log-level = INFO
offline = false
parts =
parts-directory = /sample-buildout/parts
python = buildout
verbosity = 10
<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:

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.
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
parts
A white space separated list of parts to be installed.
parts-directory
A working directory that parts can used to store data.
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.
verbosity
A log-level adjustment. Typically, this is set via the -q and -v command-line options.

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 setuptools and with local buildout scripts.

>>> sample_bootstrapped = tmpdir('sample-bootstrapped')
>>> print system(buildout
...              +' -c'+os.path.join(sample_bootstrapped, 'setup.cfg')
...              +' bootstrap'),
Warning: creating /sample-bootstrapped/setup.cfg
buildout: Creating directory /sample-bootstrapped/bin
buildout: Creating directory /sample-bootstrapped/parts
buildout: Creating directory /sample-bootstrapped/eggs
buildout: Creating directory /sample-bootstrapped/develop-eggs

Note that a basic setup.cfg was created for us.

>>> 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'))
-  setuptools-0.6-py2.3.egg
-  zc.buildout-1.0-py2.3.egg

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

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

Offline mode

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 given as a command-line option buildout:offline=true.

Controlling the installation database

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

>>> os.remove('.installed.cfg')
>>> print system(buildout+' buildout:installed=inst.cfg'),
>>> ls(sample_buildout)
-  b1.cfg
-  b2.cfg
-  base.cfg
d  bin
-  buildout.cfg
d  develop-eggs
d  eggs
-  inst.cfg
d  parts
d  recipes

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

>>> os.remove('inst.cfg')
>>> print system(buildout+' buildout:installed='),
>>> ls(sample_buildout)
-  b1.cfg
-  b2.cfg
-  base.cfg
d  bin
-  buildout.cfg
d  develop-eggs
d  eggs
d  parts
d  recipes

Extensions

An experimental feature allows code to be loaded and run after condiguration 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.extensions entry points found will be called with the buildout as an argument.

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

>>> mkdir(sample_bootstrapped, 'demo')
>>> write(sample_bootstrapped, 'demo', 'demo.py',
... """
... def ext(buildout):
...     print 'ext', 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')),
buildout: Develop: /sample-bootstrapped/demo

Now we can add the extensions option. We were a bit tricly 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 out extension is loaded and executed:

>>> print system(os.path.join(sample_bootstrapped, 'bin', 'buildout')),
ext ['buildout']
buildout: Develop: /sample-bootstrapped/demo
[1]In the future, additional mathods may be added. Older recipes with fewer methods will still be supported.
[2]If we wanted to create a distribution from this package, we would need specify much more information. See the setuptools documentation.

Automatic Buildout Updates

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

>>> ls(new_releases)
d  setuptools
-  setuptools-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]
... find-links = %(new_releases)s
... 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 setuptools and zc.buildout used:

>>> mkdir(sample_buildout, 'showversions')
>>> write(sample_buildout, 'showversions', 'showversions.py',
... """
... import pkg_resources
...
... class Recipe:
...
...     def __init__(self, buildout, name, options):
...         pass
...
...     def install(self):
...         for project in 'zc.buildout', 'setuptools':
...             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:

>>> import os
>>> os.chdir(sample_buildout)
>>> buildout = os.path.join(sample_buildout, 'bin', 'buildout')
>>> print system(buildout),
zc.buildout.easy_install: Getting new distribution for zc.buildout
zc.buildout.easy_install: Got zc.buildout 99.99
zc.buildout.easy_install: Getting new distribution for setuptools
zc.buildout.easy_install: Got setuptools 99.99
buildout: Upgraded:
  zc.buildout version 99.99,
  setuptools version 99.99;
restarting.
buildout: Develop: /sample-buildout/showversions
buildout: Installing show-versions
zc.buildout 99.99
setuptools 99.99

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

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

There are a number of cases in which the updates don’t happen. Let’s recreate the sample buildout. One case is the one in which we specify versions of zc.buildout and setuptools for which the don’t match. If we update out configuration file to specify an older version:

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

We’ll actually “upgrade” to an earlier version.

>>> print system(buildout),
buildout: Upgraded:
  zc.buildout version 1.0.0,
  setuptools version 0.6;
restarting.
buildout: Develop: /sample-buildout/showversions
buildout: Updating show-versions
zc.buildout 1.0.0
setuptools 0.6

We won’t upgrade in offline mode:

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... find-links = %(new_releases)s
... index = %(new_releases)s
... parts = show-versions
... develop = showversions
... offline = true
...
... [show-versions]
... recipe = showversions
... """ % dict(new_releases=new_releases))
>>> print system(buildout),
buildout: Develop: /sample-buildout/showversions
buildout: Updating show-versions
zc.buildout 1.0.0
setuptools 0.6

We also won’t upgrade if the buildout script bing 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]
... find-links = %(new_releases)s
... index = %(new_releases)s
... parts =
... """ % dict(new_releases=new_releases))
>>> cd(sample_buildout2)
>>> print system(buildout),
buildout: Creating directory /sample_buildout2/bin
buildout: Creating directory /sample_buildout2/parts
buildout: Creating directory /sample_buildout2/eggs
buildout: Creating directory /sample_buildout2/develop-eggs
zc.buildout.easy_install: Getting new distribution for zc.buildout
zc.buildout.easy_install: Got zc.buildout 99.99
zc.buildout.easy_install: Getting new distribution for setuptools
zc.buildout.easy_install: Got setuptools 99.99
buildout: Not upgrading because not running a local buildout command
>>> ls('bin')

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.
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.
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.

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.
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, executable, dest)
Create an egg by running the given setup file with the given Python executable 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.
find_python(version)

Find a Python executable for the given version, where version is a string like “2.4”.

This function uses the following strategy to find a Python of the given version:

  • Look for an environment variable of the form PYTHON%(version)s.
  • On windows, look for Pythonm%(version)spython
  • on Unix, try running python%(version)s or just python to get the executable

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.

The easy_install module provides a method, 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.

It supports a number of optional keyword arguments:

find-links
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://cheeseshop.python.org/pypi, 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.

executable
A path to a Python executable. Distributions will ne installed using this executable and will be for the matching Python version.
path
A list of additional directories to search for locally-installed distributions.
always_unzip
A flag indicating that newly-downloaded distributions should be directories even if they could be installed as zip files.

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),
<html><body>
<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="demoneeded-1.0.zip">demoneeded-1.0.zip</a><br>
<a href="demoneeded-1.1.zip">demoneeded-1.1.zip</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,
...     links=[link_server], index=link_server+'index/')

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

And the actual eggs were added to the eggs directory.

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

If we ask for the demo distribution without a version restriction, we’ll get the newer version:

>>> ws = zc.buildout.easy_install.install(
...     ['demo'], dest, links=[link_server], index=link_server+'index/')
>>> ls(dest)
-  demo-0.2-py2.4.egg
-  demo-0.3-py2.4.egg
-  demoneeded-1.1-py2.4.egg

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 sprcific version.

>>> ws = zc.buildout.easy_install.install(
...     ['demo', 'other', 'demoneeded==1.0'], dest,
...     links=[link_server], index=link_server+'index/')
>>> for dist in ws:
...     print dist
demo 0.3
other 1.0
demoneeded 1.0
>>> ls(dest)
-  demo-0.2-py2.4.egg
-  demo-0.3-py2.4.egg
-  demoneeded-1.0-py2.4.egg
-  demoneeded-1.1-py2.4.egg
d  other-1.0-py2.4.egg

We can request that eggs be unzipped even if they are zip safe. This can be useful when debugging.

>>> rmdir(dest)
>>> dest = tmpdir('sample-install')
>>> ws = zc.buildout.easy_install.install(
...     ['demo'], dest, links=[link_server], index=link_server+'index/',
...     always_unzip=True)
>>> ls(dest)
d  demo-0.3-py2.4.egg
d  demoneeded-1.1-py2.4.egg
>>> rmdir(dest)
>>> dest = tmpdir('sample-install')
>>> ws = zc.buildout.easy_install.install(
...     ['demo'], dest, links=[link_server], index=link_server+'index/',
...     always_unzip=True)
>>> ls(dest)
d  demo-0.3-py2.4.egg
d  demoneeded-1.1-py2.4.egg

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 four 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 Python executable to use, and
  1. 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/python2.4
<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__':
    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 antry 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/python2.4
<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__':
    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/python2.4
import sys
<BLANKLINE>
sys.path[0:0] = [
  '/sample-install/demo-0.3-py2.4.egg',
  '/sample-install/demoneeded-1.1-py2.4.egg',
  ]
<BLANKLINE>
_interactive = True
if len(sys.argv) > 1:
    import getopt
    _options, _args = getopt.getopt(sys.argv[1:], 'ic:')
    _interactive = False
    for (_opt, _val) in _options:
        if _opt == '-i':
            _interactive = True
        elif _opt == '-c':
            exec _val
<BLANKLINE>
    if _args:
        sys.argv[:] = _args
        execfile(sys.argv[0])
<BLANKLINE>
if _interactive:
    import code
    code.interact(banner="", local=globals())

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

An additional argumnet 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')),
3 1

Including extra paths in scripts

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

>>> scripts = zc.buildout.easy_install.scripts(
...    ['demo'], ws, sys.executable, bin, dict(demo='run'),
...    extra_paths=['/foo/bar'])
>>> cat(bin, 'run') # doctest: +NORMALIZE_WHITESPACE
#!/usr/local/bin/python2.4
<BLANKLINE>
import sys
sys.path[0:0] = [
  '/sample-install/demo-0.3-py2.4.egg',
  '/sample-install/demoneeded-1.1-py2.4.egg',
  '/foo/bar',
  ]
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
    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/python2.4
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__':
    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/python2.4
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__':
    eggrecipedemo.main(1, 2)

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:

links
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://cheeseshop.python.org/pypi, 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.

executable
A path to a Python executable. Distributions will ne installed using this executable and will be for the matching Python version.
path
A list of additional directories to search for locally-installed distributions.
always_unzip
A flag indicating that newly-downloaded distributions should be directories even if they could be installed as zip files.

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
    PyModule_AddObject(m, "val", PyInt_FromLong(2));
#else
    PyModule_AddObject(m, "val", PyInt_FromLong(EXTDEMO));
#endif
}

The extension depends on a system-dependnt 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')},
...   links=[link_server], index=link_server+'index/')
'/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-0.3-py2.4.egg
d  demoneeded-1.1-py2.4.egg
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.
executable
A path to a Python executable. Distributions will ne installed using this executable and will be for the matching Python version.

We have a local directory containing the extdemo source:

>>> ls(extdemo)
-  MANIFEST
-  MANIFEST.in
-  README
-  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')})
'/sample-install/extdemo.egg-link'

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  demo-0.3-py2.4.egg
d  demoneeded-1.1-py2.4.egg
d  extdemo-1.4-py2.4-linux-i686.egg
-  extdemo.egg-link

And that the source directory contains the compiled extension:

>>> ls(extdemo)
-  MANIFEST
-  MANIFEST.in
-  README
d  build
-  extdemo.c
d  extdemo.egg-info
-  extdemo.so
-  setup.py

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