slapos.recipe.template 5.1

Templating recipe with remote resource support.

Contents

• default recipe

  • Options

    • md5sum - check file integrity

    • inline

    • mode - specify filesystem permissions

• jinja2

  • Options

    • md5sum, mode

    • once - avoiding file re-creation

    • context - template variables and section dependency

    • extensions - Jinja2 extensions

    • import-delimiter, import-list - template imports

    • update - force rerendering on update

    • encoding

  • FAQ

  • Errors in template

• History

  • 5.1 (2022-10-24)

  • 5.0 (2022-02-03)

  • 4.6 (2021-06-08)

  • 4.5 (2020-01-08)

  • 4.4 (2019-01-24)

  • 4.3 (2018-01-25)

  • 4.2 (2017-12-12)

  • 4.1 (2017-10-18)

  • 4.0 (2017-10-13)

  • 3.0 (2017-05-23)

  • 2.10 (2017-01-18)

  • 2.9 (2015-11-18)

  • 2.8 (2015-06-25)

  • 2.7 (2015-05-18)

  • 2.6 (2014-11-26)

  • 2.5 (2013-08-07)

  • 2.4.3 (2013-08-02)

  • 2.4.2 (2012-08-21)

  • 2.4.1 (2012-08-01)

  • 2.4 (2012-06-01)

  • 2.3 (2012-03-29)

  • 2.2 (2011-10-12)

  • 2.1 (2011-10-12)

  • 2.0 (2011-10-12)

  • 1.1 (2011-05-30)

Collection of recipes to generate a file from a template that can be either inline or fetched with the buildout download API.

Inspired by collective.recipe.template.

default recipe

The default recipe generates a file (option output) from a template using buildout expansion. The template is specified with either url (optionally combined with md5sum) or inline.

Here is a simple buildout:

>>> base = """
... [buildout]
... parts = template
...
... [section]
... option = value
...
... [template]
... recipe = slapos.recipe.template
... url = template.in
... output = template.out
... """
>>> write('buildout.cfg', base)

A simple template:

>>> write('template.in', '${section:option}')

And the output file has been parsed by buildout itself:

>>> run_buildout()
Installing template.
>>> cat('template.out')
value

The recipe relies on buildout expansion to pull sections it depends on, which implies that the rendering (including the download if requested) is done during the initialization phase.

Options

md5sum - check file integrity

If the template is specified with the url option, an MD5 checksum can be given to check the contents of the template:

>>> base += """
... md5sum = 1993226f57db37c4a19cb785f826a1aa
... """
>>> write(sample_buildout, 'buildout.cfg', base)
>>> run_buildout()
Uninstalling template.
Installing template.
>>> cat('template.out')
value

In such case, updating the part does nothing:

>>> write('template.out', 'altered')
>>> run_buildout()
Updating template.
>>> cat('template.out')
altered

In case of checksum mismatch:

>>> run_buildout('template:md5sum=00000000000000000000000000000000')
While:
  Installing.
  Getting section template.
  Initializing section template.
Error: MD5 checksum mismatch for local resource at 'template.in'.

inline

You may prefer to inline small templates:

>>> write('buildout.cfg', """
... [buildout]
... parts = template
...
... [section]
... option = inlined
...
... [template]
... recipe = slapos.recipe.template
... inline = ${section:option}
... output = template.out
... """)
>>> run_buildout()
Uninstalling template.
Installing template.
>>> cat('template.out')
inlined

Note that in such case, the rendering is done by buildout itself: it just creates a file with the value of inline.

mode - specify filesystem permissions

By default, executable permissions are set if the content of the output file looks like an executable script, i.e. it has a shebang that points to an executable file. This is done by respecting umask:

>>> import os, stat
>>> os.access('template.out', os.X_OK)
False
>>> run_buildout('section:option=#!/bin/sh')
Uninstalling template.
Installing template.
>>> os.access('template.out', os.X_OK)
True

File permissions can be forced using the mode option in octal representation (no need for 0-prefix):

>>> run_buildout('template:mode=627')
Uninstalling template.
Installing template.
>>> print("0%o" % stat.S_IMODE(os.stat('template.out').st_mode))
0627

jinja2

Similar to the default recipe but the template syntax is Jinja2 instead of buildout. Other significant differences are:

• Rendering, and download if requested, is done during the install phase.

• Dependencies are explicit (see context option) instead of deduced from the template.

• Some extra features (options detailed below).

For backward compatibility, the following old options are still supported:

• The generated file can be specified with rendered instead of output.

• The template can be specified with template instead of url/inline. An inline template is prefixed with inline: + an optional newline.

Example demonstrating some types:

>>> write('buildout.cfg',
... '''
... [buildout]
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... url = foo.in
... output = foo
... context =
...     key     bar          section:key
...     key     recipe       :recipe
...     raw     knight       Ni !
...     import  json_module  json
...     section param_dict   parameter-collection
...
... [parameter-collection]
... foo = 1
... bar = bar
...
... [section]
... key = value
... ''')

And according Jinja2 template (kept simple, control structures are possible):

>>> write('foo.in',
...     '{{bar}}\n'
...     'Knights who say "{{knight}}"\n'
...     '${this:is_literal}\n'
...     '${foo:{{bar}}}\n'
...     'swallow: {{ json_module.dumps(("african", "european")) }}\n'
...     'parameters from section: {{ param_dict | dictsort }}\n'
...     'Rendered with {{recipe}}\n'
...     'UTF-8 text: привет мир!\n'
...     'Unicode text: {{ "你好世界" }}\n'
... )

We run buildout:

>>> run_buildout()
Installing template.

And the template has been rendered:

>>> cat('foo')
value
Knights who say "Ni !"
${this:is_literal}
${foo:value}
swallow: ["african", "european"]
parameters from section: [('bar', 'bar'), ('foo', '1')]
Rendered with slapos.recipe.template:jinja2
UTF-8 text: привет мир!
Unicode text: 你好世界

Options

md5sum, mode

Same as for the default recipe.

once - avoiding file re-creation

Path of a marker file to prevents rendering altogether.

Normally, each time the section is installed/updated the file gets re-generated. This may be undesirable in some cases.

once allows specifying a marker file, which when present prevents template rendering:

>>> write('buildout.cfg',
... '''
... [buildout]
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... inline = dummy
... output = foo_once
... once = foo_flag
... ''')
>>> run_buildout()
Uninstalling template.
Installing template.
The template install returned None.  A path or iterable os paths should be returned.

Template was rendered:

>>> cat('foo_once')
dummy

And canary exists:

>>> import os
>>> os.path.exists('foo_flag')
True

Remove rendered file and re-render:

>>> os.unlink('foo_once')
>>> with open('buildout.cfg', 'a') as f:
...     f.writelines(['extra = useless'])
>>> run_buildout()
Uninstalling template.
Installing template.
The template install returned None.  A path or iterable os paths should be returned.
Unused options for template: 'extra'.

Template was not rendered:

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

Removing the canary allows template to be re-rendered:

>>> os.unlink('foo_flag')
>>> with open('buildout.cfg', 'a') as f:
...     f.writelines(['moreextra = still useless'])
>>> run_buildout()
Uninstalling template.
Installing template.
The template install returned None.  A path or iterable os paths should be returned.
Unused options for template: 'extra'.
>>> cat('foo_once')
dummy

It’s also possible to use the same file for rendered and once:

>>> write('buildout.cfg',
... '''
... [buildout]
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... inline = initial content
... output = rendered
... once = ${:output}
... ''')
>>> run_buildout() # doctest: +ELLIPSIS
Uninstalling template.
Installing template.
The template install returned None.  A path or iterable os paths should be returned.

Template was rendered:

>>> cat('rendered')
initial content

When buildout options are modified, the template will not be rendered again:

>>> with open('buildout.cfg', 'a') as f:
...     f.writelines(['inline = something different'])

>>> run_buildout()
Uninstalling template.
Installing template.
The template install returned None.  A path or iterable os paths should be returned.

Even though we used a different template, the file still contain the first template:

>>> cat('rendered')
initial content

context - template variables and section dependency

Jinja2 context specification, one variable per line, with 3 whitespace-separated parts: type, name and expression. Available types are described below. “name” is the variable name to declare. Expression semantic varies depending on the type.

Available types:

raw

Immediate literal string.

key

Indirect literal string.

import

Import a python module.

section

Make a whole buildout section available to template, as a dictionary.

Indirection targets are specified as: [section]:key . It is possible to use buildout’s buit-in variable replacement instead instead of key type, but keep in mind that different lines are different variables for this recipe. It might be what you want (factorising context chunk declarations), otherwise you should use indirect types.

You can use other part of buildout in the template. This way this parts will be installed as dependency:

>>> write('buildout.cfg', '''
... [buildout]
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... inline = {{bar}}
... output = foo
... context = key bar dependency:foobar
...
... [dependency]
... foobar = dependency content
... recipe = zc.buildout:debug
... ''')

>>> run_buildout()
Uninstalling template.
Installing dependency.
  foobar='dependency content'
  recipe='zc.buildout:debug'
Installing template.

This way you can get options which are computed in the __init__ of the dependent recipe.

Let’s create a sample recipe modifying its option dict:

>>> write('setup.py',
... '''
... from setuptools import setup
...
... setup(name='samplerecipe',
...       entry_points = {
...           'zc.buildout': [
...                'default = main:Recipe',
...           ],
...       }
...      )
... ''')
>>> write('main.py',
... '''
... class Recipe(object):
...
...     def __init__(self, buildout, name, options):
...         options['data'] = 'foobar'
...
...     def install(self):
...         return []
... ''')

Let’s just use buildout.cfg using this egg:

>>> write('buildout.cfg',
... '''
... [buildout]
... develop = .
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... inline =
...   {{bar}}
... output = foo
... context = key bar sample:data
...
... [sample]
... recipe = samplerecipe
... ''')
>>> run_buildout()
Develop: '/sample-buildout/.'
Uninstalling template.
Uninstalling dependency.
Installing sample.
Installing template.
>>> cat('foo')
foobar

extensions - Jinja2 extensions

Jinja2 extensions to enable when rendering the template, whitespace-separated. By default, none is loaded.

>>> write('foo.in',
... '''{% set foo = ['foo'] -%}
... {% do foo.append(bar) -%}
... {{ foo | join(', ') }}''')
>>> write('buildout.cfg',
... '''
... [buildout]
... develop = .
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... url = foo.in
... output = foo
... context = key bar buildout:parts
... # We don't actually use all those extensions in this minimal example.
... extensions = jinja2.ext.do jinja2.ext.loopcontrols
...   jinja2.ext.with_
... ''')
>>> run_buildout()
Develop: '/sample-buildout/.'
Uninstalling template.
Uninstalling sample.
Installing template.

>>> cat('foo')
foo, template

import-delimiter, import-list - template imports

import-delimiter specifies the delimiter character for in-temlate imports. Defaults to /.

import-list is a list of import paths. Format is similar to context. “name” becomes import’s base name. Available types:

rawfile

Literal path of a file.

file

Indirect path of a file.

rawfolder

Literal path of a folder. Any file in such folder can be imported.

folder

Indirect path of a folder. Any file in such folder can be imported.

Here is a simple template importing an equaly-simple library:

>>> write('template.in', '''
... {%- import "library" as library -%}
... {{ library.foo() }}
... ''')
>>> write('library.in', '{% macro foo() %}FOO !{% endmacro %}')

To import a template from rendered template, you need to specify what can be imported:

>>> write('buildout.cfg', '''
... [buildout]
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... url = template.in
... output = bar
... import-list = rawfile library library.in
... ''')
>>> run_buildout()
Uninstalling template.
Installing template.
>>> cat('bar')
FOO !

Just like context definition, it also works with indirect values:

>>> write('buildout.cfg', '''
... [buildout]
... parts = template
...
... [template-library]
... path = library.in
...
... [template]
... recipe = slapos.recipe.template:jinja2
... url = template.in
... output = bar
... import-list = file library template-library:path
... ''')
>>> run_buildout()
Uninstalling template.
Installing template.
>>> cat('bar')
FOO !

This also works to allow importing from identically-named files in different directories:

>>> write('template.in', '''
... {%- import "dir_a/1.in" as a1 -%}
... {%- import "dir_a/2.in" as a2 -%}
... {%- import "dir_b/1.in" as b1 -%}
... {%- import "dir_b/c/1.in" as bc1 -%}
... {{ a1.foo() }}
... {{ a2.foo() }}
... {{ b1.foo() }}
... {{ bc1.foo() }}
... ''')
>>> mkdir('a')
>>> mkdir('b')
>>> mkdir(join('b', 'c'))
>>> write(join('a', '1.in'), '{% macro foo() %}a1foo{% endmacro %}')
>>> write(join('a', '2.in'), '{% macro foo() %}a2foo{% endmacro %}')
>>> write(join('b', '1.in'), '{% macro foo() %}b1foo{% endmacro %}')
>>> write(join('b', 'c', '1.in'), '{% macro foo() %}bc1foo{% endmacro %}')

All templates can be accessed inside both folders:

>>> write('buildout.cfg', '''
... [buildout]
... parts = template
...
... [template-library]
... path = library.in
...
... [template]
... recipe = slapos.recipe.template:jinja2
... url = template.in
... output = bar
... import-list =
...     rawfolder dir_a a
...     rawfolder dir_b b
... ''')
>>> run_buildout()
Uninstalling template.
Installing template.
>>> cat('bar')
a1foo
a2foo
b1foo
bc1foo

It is possible to override default path delimiter (without any effect on final path):

>>> write('template.in', r'''
... {%- import "dir_a\\1.in" as a1 -%}
... {%- import "dir_a\\2.in" as a2 -%}
... {%- import "dir_b\\1.in" as b1 -%}
... {%- import "dir_b\\c\\1.in" as bc1 -%}
... {{ a1.foo() }}
... {{ a2.foo() }}
... {{ b1.foo() }}
... {{ bc1.foo() }}
... ''')
>>> write('buildout.cfg', r'''
... [buildout]
... parts = template
...
... [template-library]
... path = library.in
...
... [template]
... recipe = slapos.recipe.template:jinja2
... url = template.in
... output = bar
... import-delimiter = \
... import-list =
...     rawfolder dir_a a
...     rawfolder dir_b b
... ''')
>>> run_buildout()
Uninstalling template.
Installing template.
>>> cat('bar')
a1foo
a2foo
b1foo
bc1foo

update - force rerendering on update

By default, and like the default recipe, nothing is done on update if the template is known in advance to be the same, either because it’s inline or a md5sum is given:

>>> write('buildout.cfg',
... '''
... [buildout]
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... inline = {{ os.environ['FOO'] }}
... output = foo
... context = import os os
... ''')
>>> os.environ['FOO'] = '1'
>>> run_buildout()
Uninstalling template.
Installing template.
>>> cat('foo')
1
>>> os.environ['FOO'] = '2'
>>> run_buildout()
Updating template.
>>> cat('foo')
1

But Jinja2 is such that the output may depend on other things than buildout data and it may be wanted to force update in such case:

>>> with open('buildout.cfg', 'a') as f:
...     f.writelines(['update = true'])
>>> run_buildout()
Uninstalling template.
Installing template.
>>> cat('foo')
2
>>> os.environ['FOO'] = '1'
>>> run_buildout()
Updating template.
>>> cat('foo')
1
>>> del os.environ['FOO']

encoding

Encoding for input template and output file. Defaults to utf-8.

FAQ

Q: How do I generate ${foo:bar} where foo comes from a variable ?

A: {{ '${' ~ foo_var ~ ':bar}' }}

This is required as jinja2 fails parsing “${{{ foo_var }}:bar}”. Though, jinja2 succeeds at parsing “${foo:{{ bar_var }}}” so this trick isn’t needed for that case.

Errors in template

>>> write('template.in', '''\
... foo
... {%
... bar
... ''')
>>> write('buildout.cfg', '''
... [buildout]
... parts = template
...
... [template]
... recipe = slapos.recipe.template:jinja2
... url = template.in
... output = foo
... ''')
>>> 0; run_buildout() # doctest: +ELLIPSIS
0...
While:
  Installing template.
...
Traceback (most recent call last):
  ...
  File "template.in", line 3, in template
    bar
...TemplateSyntaxError: Encountered unknown tag 'bar'.

History

5.1 (2022-10-24)

• Allow an overriding section to unset ‘url’ in order to instead define ‘inline’.

• Fix incorrect initialization of buildout download API.

5.0 (2022-02-03)

• jinja2: annotate compiled source with source path rather than download destination path.

• default: bring some of the jinja2 improvements by refactoring the 2 recipes.

• default: add support for inline templates.

• Improve condition to determine if the output file is executable or not.

• jinja2: fix default context (range missing, Py2/Py3 inconsistencies).

• jinja2: new options to specify source (template -> url/inline) and destination (rendered -> output) the same way as the default recipe. rendered & template are deprecated.

• jinja2: by default, rerender on update only if the template may have changed, and new boolean option to force update like it used to be.

4.6 (2021-06-08)

• Fix leaking temporary files with templates from URLs

4.5 (2020-01-08)

• jinja2: Prevent ‘once’ from overwriting ‘rendered’

4.4 (2019-01-24)

• jinja2: add bytes and six

4.3 (2018-01-25)

• jinja2: Compile the same source only once and use compiled source next time.

4.2 (2017-12-12)

• jinja2: try to not rewrite on update if there’s no change

4.1 (2017-10-18)

• Fix $$ escaping in basic templates.

4.0 (2017-10-13)

• jinja2: read template at install/update and fix ‘mode’ option

• Add support for Python 3.

3.0 (2017-05-23)

• jinja2: make ‘import’ return the leaf module instead of the root one.

2.10 (2017-01-18)

• jinja2: Add support for render-once.

2.9 (2015-11-18)

• jinja2: Add support for non-ascii templates. Encoding for input/output and imported files can be set via new “encoding” parameter which defaults to utf-8.

2.8 (2015-06-25)

• jinja2: new assert function.

2.7 (2015-05-18)

• jinja2: fix display of source in traceback when there is an error in the root template (or in instance parameters).

2.6 (2014-11-26)

• jinja2: add many built-in functions from Python.

2.5 (2013-08-07)

• Fix file import with Jinja2 >= 2.7

2.4.3 (2013-08-02)

• jinja2: add support for inline templates.

2.4.2 (2012-08-21)

• jinja2: Mode shall be used instead of umask. [Vincent Pelletier]

• jinja2: Add jinja2 “import” directive support. [Vincent Pelletier, Timothee Lacroix]

• Added rawfile and rawfolder types. [Vincent Pelletier, Timothee Lacroix]

• Reworked loader classes [Vincent Pelletier]

2.4.1 (2012-08-01)

• jinja2: Make “context” parameter really optional. [Vincent Pelletier]

2.4 (2012-06-01)

• Provide access to zc.buildout.buildout.dumps when it exists. [Vincent Pelletier]

• Fix missing jinja2 entry point documentation in pacakge description [Vincent Pelletier]

2.3 (2012-03-29)

• Add jinja2 entry point with jinja2 template support. [Vincent Pelletier]

2.2 (2011-10-12)

• Include missing files in package. [Łukasz Nowak]

2.1 (2011-10-12)

• Description update. [Łukasz Nowak]

2.0 (2011-10-12)

• Dropping collective.recipe.template dependency. [Romain Courteaud, Antoine Catton]

1.1 (2011-05-30)

• Moved out from slapos.cookbook in order to minimise depenencies [Łukasz Nowak]