buildout.recipe.isolation 0.2.0

食谱交付成果

• 包含指定分布（s）包及其依赖包（s）的目录。

• 包含 .pth 文件的目录，其中列出隔离上下文中每个包的绝对路径。

• 包含从分布（s）包及其依赖包生成的脚本。

依赖排除

现在让我们尝试一个稍大一些的示例构建，我们可以用它来展示从特定隔离中排除依赖项。

让我们根据上一个构建配置创建一个新的构建配置。此配置已设置为隔离 bigdemo 分发及其依赖项，但排除 demoneeded 依赖项。

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... parts =
...     demoneeded
...     demo
... find-links = %(server)s
... index = %(server)s/index
...
... [demoneeded]
... recipe = buildout.recipe.isolation
... dists = demoneeded
...
... [demo]
... recipe = buildout.recipe.isolation
... dists = bigdemo
... exclude-dists = ${demoneeded:dists}
... """ % dict(server=link_server))

>>> print system(buildout), #doctest: +ELLIPSIS
Uninstalling demo.
Installing demoneeded.
demoneeded: Copying demoneeded to the destination directory.
Installing demo.
Getting distribution for 'bigdemo'.
Got bigdemo 0.1.
Getting distribution for 'demo'.
Got demo 0.4c1.
demo: Copying demo to the destination directory.
demo: Copying bigdemo to the destination directory.
demo: Generated script '/sample-buildout/parts/demo-scripts/demo'.

检查隔离结果

>>> ls(sample_buildout, 'parts/demo')
-  bigdemo-0.1-py2.6.egg
-  demo-0.4c1-py2.6.egg
>>> ls(sample_buildout, 'parts/demoneeded')
d  demoneeded-1.2c1-py2.6.egg

脚本生成

某些分发在其软件包中提供命令行脚本。Buildout 通常为我们生成这些脚本，因为它需要向脚本提供构建的软件包。它通过将分发位置注入 Python 系统路径来完成此操作。在某些情况下，我们不希望将任何内容注入 Python 系统路径，因为我们可能已经将生成的 .pth 文件放置在虚拟环境的 site-packages 目录中。而在其他情况下，我们可能希望将 .pth 文件作为导入解析的手段提供。让我们更仔细地看看这两种情况。

对于一般情况，我们可能希望将我们的 .pth 文件提供给脚本。此外，我们可能还希望提供任何依赖隔离可能生成的 .pth 文件。以下是一个示例。

>>> import sys
>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... parts =
...     demoneeded
...     demo
... find-links = %(server)s
... index = %(server)s/index
...
... [demoneeded]
... recipe = buildout.recipe.isolation
... dists = demoneeded
...
... [demo]
... recipe = buildout.recipe.isolation
... dists = bigdemo
... exclude-dists = ${demoneeded:dists}
... extra-pth = ${demoneeded:pth-file-location}
... executable = %(python)s
... """ % dict(server=link_server, python=sys.executable))
>>> print system(buildout), #doctest: +ELLIPSIS
Uninstalling demo.
Uninstalling demoneeded.
Installing demoneeded.
demoneeded: Copying demoneeded to the destination directory.
Installing demo.
demo: Copying demo to the destination directory.
demo: Copying bigdemo to the destination directory.
demo: Generated script '/sample-buildout/parts/demo-scripts/demo'.

生成的脚本应包含两个 .pth 文件。demo.pth 文件已定义并从上下文中的配方生成。demoneeded.pth 文件是由 demoneeded 部分生成的，并使用 extra-pth 配方选项引入。

>>> if sys.platform == 'win32':
...    script_name = 'demo-script.py'
... else:
...    script_name = 'demo'
>>> script_dir = 'parts/demo-scripts'
>>> f = open(os.path.join(sample_buildout, script_dir, script_name))
>>> shebang = f.readline().strip()
>>> if shebang[:3] == '#!"' and shebang[-1] == '"':
...     shebang = '#!'+shebang[3:-1]
>>> shebang == '#!' + os.path.realpath(sys.executable)
True
>>> print f.read(), # doctest: +NORMALIZE_WHITESPACE
<BLANKLINE>
import sys
def pth_injector(pth_file):
    path_file = open(pth_file, 'r')
    sys.path[0:0] = [line
        for line in path_file.read().split('\n')
        if line is not None]
<BLANKLINE>
pth_files = ['/sample-buildout/parts/demo-pth/demo.pth', '/sample-buildout/parts/demoneeded-pth/demoneeded.pth']
for pth in pth_files:
    pth_injector(pth)
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
    eggrecipedemo.main()
>>> f.close()

第二种情况是将 .pth 文件存放到虚拟环境中。让我们为了演示的目的，在构建结构内部设置一个 伪造 的虚拟环境结构。

>>> virtenv = os.path.join(sample_buildout, 'virtenv')
>>> mkdir(virtenv)
>>> mkdir(virtenv, 'bin')
>>> mkdir(virtenv, 'lib')
>>> mkdir(virtenv, 'lib', 'python2.6')
>>> mkdir(virtenv, 'lib', 'python2.6', 'site-packages')
>>> site_pkgs = os.path.join(virtenv, 'lib', 'python2.6', 'site-packages')

对于这个演示，我们实际上只需要 site-packages 目录。

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... parts =
...     demoneeded
...     demo
... find-links = %(server)s
... index = %(server)s/index
...
... [demoneeded]
... recipe = buildout.recipe.isolation
... dists = demoneeded
... pth-file-location = %(site_pkgs)s
...
... [demo]
... recipe = buildout.recipe.isolation
... dists = bigdemo
... exclude-dists = ${demoneeded:dists}
... pth-file-location = %(site_pkgs)s
... exclude-own-pth = trUE
... python = %(python)s
... """ % dict(server=link_server, python=sys.executable,
...     site_pkgs=site_pkgs))
>>> print system(buildout), #doctest: +ELLIPSIS
Uninstalling demo.
Uninstalling demoneeded.
Installing demoneeded.
demoneeded: Copying demoneeded to the destination directory.
Installing demo.
demo: Copying demo to the destination directory.
demo: Copying bigdemo to the destination directory.
demo: Generated script '/sample-buildout/parts/demo-scripts/demo'.

现在，如果我们打印出 demo 脚本，我们会发现没有提到 .pth 文件。

>>> f = open(os.path.join(sample_buildout, script_dir, script_name))
>>> shebang = f.readline().strip()
>>> if shebang[:3] == '#!"' and shebang[-1] == '"':
...     shebang = '#!'+shebang[3:-1]
>>> shebang == '#!' + os.path.realpath(sys.executable)
True
>>> print f.read(), # doctest: +NORMALIZE_WHITESPACE
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
    eggrecipedemo.main()
>>> f.close()

为什么这会起作用？如果我们使用虚拟环境的 Python 可执行文件，它会加载 site-packages 目录以及其中的任何 .pth 文件。这将反过来加载我们使用构建生成的模块。

隔离的预演

在某些情况下，在将资源传输到最终目的地之前在本地构建软件包很有用。为此，我们可以使用 stage-locally 选项对隔离过程进行预演。

此选项将允许您设置 dists-location、scripts-location 和 pth-file-location 作为最终目的地，但将结果放置在其默认构建位置。如果您还记得，默认构建位置在构建的 parts 目录中。

让我们通过创建一个类似的构建配置来了解这是如何工作的，但现在我们将 stage-locally 选项设置为 true。

>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... parts =
...     demo
... find-links = %(server)s
... index = %(server)s/index
...
... [demo]
... recipe = buildout.recipe.isolation
... dists = bigdemo
... dists-location = %(site_pkgs)s
... scripts-location = %(bin_dir)s
... pth-location = %(site_pkgs)s
... executable = %(python)s
... stage-locally = true
... """ % dict(server=link_server,
...            bin_dir=os.path.join(virtenv, 'bin'),
...            python=os.path.join(virtenv, 'bin', 'python'),
...            site_pkgs=site_pkgs))
>>> print system(buildout), #doctest: +ELLIPSIS
Uninstalling demo.
Uninstalling demoneeded.
Installing demo.
demo: Copying demo to the staging directory.
demo: Copying demoneeded to the staging directory.
demo: Copying bigdemo to the staging directory.
demo: Can't find the executable on the filesystem. Perhaps this setup is not destine to be used on this machine. So we are using the given executable value /sample-buildout/virtenv/bin/python as is.
demo: Generated script '/sample-buildout/parts/demo-scripts/demo'.

为了验证事物已被部署，让我们仔细查看演示脚本以确认一切是否按计划进行。首先，我们期望脚本位于parts目录中

>>> parts_dir = os.path.join(sample_buildout, 'parts')
>>> demo_script = os.path.join(parts_dir, 'demo-scripts', 'demo')
>>> os.path.exists(demo_script)
True
>>> cat(demo_script)
#!/sample-buildout/virtenv/bin/python
<BLANKLINE>
import sys
def pth_injector(pth_file):
    path_file = open(pth_file, 'r')
    sys.path[0:0] = [line
        for line in path_file.read().split('\n')
        if line is not None]
<BLANKLINE>
pth_files = ['/sample-buildout/virtenv/lib/python2.6/site-packages/demo.pth']
for pth in pth_files:
    pth_injector(pth)
<BLANKLINE>
import eggrecipedemo
<BLANKLINE>
if __name__ == '__main__':
    eggrecipedemo.main()

此外，我们还想检查pth位置是否正确，并且pth本身是否与parts一起位于部署区域

>>> demo_pth = os.path.join(parts_dir, 'demo-pth', 'demo.pth')
>>> cat(demo_pth)
/sample-buildout/virtenv/lib/python2.6/site-packages/demo-0.4c1-py2.1.egg
/sample-buildout/virtenv/lib/python2.6/site-packages/demoneeded-1.2c1-py2.1.egg
/sample-buildout/virtenv/lib/python2.6/site-packages/bigdemo-0.1-py2.1.egg

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