zc.buildout 1.0.0b17

Feature Changes

• Added documentation for some previously undocumented features of the easy_install APIs.

• By popular demand, added a -o command-line option that is a short hand for the assignment buildout:offline=true.

Bugs Fixed

• When deciding whether recipe develop eggs had changed, buildout incorrectly considered files in .svn and CVS directories.

Feature Changes

• Configuration files can now be loaded from URLs.

Bugs Fixed

• https://bugs.launchpad.net/products/zc.buildout/+bug/71246

  Buildout extensions installed as eggs couldn’t be loaded in offline mode.

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.

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.

Feature Changes

• Variable substitutions now reflect option data written by recipes.

• A part referenced by a part in a parts list is now added to the parts list before the referencing part. This means that you can omit parts from the parts list if they are referenced by other parts.

• Added a develop function to the easy_install module to aid in creating develop eggs with custom build_ext options.

• The build and develop functions in the easy_install module now return the path of the egg or egg link created.

• Removed the limitation that parts named in the install command can only name configured parts.

• Removed support ConfigParser-style variable substitutions (e.g. %(foo)s). Only the string-template style of variable (e.g. ${section:option}) substitutions will be supported. Supporting both violates “there’s only one way to do it”.

• Deprecated the buildout-section extendedBy option.

Bugs Fixed

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

Feature Changes

• 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.

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.

Loading Configuration from URLs

Configuration files can be loaded from URLs. To see how this works, we’ll set up a web server with some configuration files.

>>> server_data = tmpdir('server_data')

>>> write(server_data, "r1.cfg",
... """
... [debug]
... op1 = r1 1
... op2 = r1 2
... """)

>>> write(server_data, "r2.cfg",
... """
... [buildout]
... extends = r1.cfg
...
... [debug]
... op2 = r2 2
... op3 = r2 3
... """)

>>> server_url = start_server(server_data)

>>> write('client.cfg',
... """
... [buildout]
... develop = recipes
... parts = debug
... extends = %(url)s/r2.cfg
...
... [debug]
... recipe = recipes:debug
... name = base
... """ % dict(url=server_url))

>>> print system(buildout+ ' -c client.cfg'),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: Installing debug
name base
op1 r1 1
op2 r2 2
op3 r2 3
recipe recipes:debug

Here we specified a URL for the file we extended. The file we downloaded, itself refered to a file on the server using a relative URL reference. Relative references are interpreted relative to the base URL when they appear in configuration files loaded via URL.

We can also specify a URL as the configuration file to be used by a buildout.

>>> os.remove('client.cfg')
>>> write(server_data, 'remote.cfg',
... """
... [buildout]
... develop = recipes
... parts = debug
... extends = r2.cfg
...
... [debug]
... recipe = recipes:debug
... name = remote
... """)

>>> print system(buildout + ' -c ' + server_url + '/remote.cfg'),
Error: Missing option: buildout:directory

Normally, the buildout directory defaults to directory containing a configuration file. This won’t work for configuration files loaded from URLs. In this case, the buildout directory would normally be defined on the command line:

>>> print system(buildout
...              + ' -c ' + server_url + '/remote.cfg'
...              + ' buildout:directory=' + sample_buildout
...              ),
buildout: Develop: /sample-buildout/recipes
buildout: Uninstalling debug
buildout: Installing debug
name remote
op1 r1 1
op2 r2 2
op3 r2 3
recipe recipes:debug

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 [options and assignments] [command [command arguments]]

The following options are supported:

-h (or –help)

Print basic usage information. If this option is used, then all other options are ignored.

-c filename

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

-v

Increment the verbosity by 10. The verbosity is used to adjust the logging level. The verbosity is subtracted from the numeric value of the log-level option specified in the configuration file.

-q

Decrement the verbosity by 10.

-U

Don’t read user-default configuration.

-o

Run in off-line mode. This is equivalent to the assignment buildout:offline=true.

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

To load an extension, we use the extensions option and list one or more distribution requirements, on separate lines. The distributions named will be loaded and any zc.buildout.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 our extension is loaded and executed:

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

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, then the 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.

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

3. The destination directory.

The bin directory now contains a generated script:

>>> ls(bin)
-  demo

The return value is a list of the scripts generated:

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

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

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

>>> cat(bin, 'demo') # doctest: +NORMALIZE_WHITESPACE
#!/usr/local/bin/python2.4
<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