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zope.app.appsetup 4.0.0

Zope app setup helper

Bootstrap helpers

The bootstrap helpers provide a number of functions that help with bootstrapping.

The bootStrapSubscriber function makes sure that there is a root object. It subscribes to DatabaseOpened events:

>>> from zope.app.appsetup import bootstrap
>>> import zope.processlifetime
>>> from ZODB.tests import util
>>> db = util.DB()
>>> bootstrap.bootStrapSubscriber(zope.processlifetime.DatabaseOpened(db))

The subscriber makes sure that there is a root folder:

>>> from zope.app.publication.zopepublication import ZopePublication
>>> conn = db.open()
>>> root = conn.root()[ZopePublication.root_name]
>>> sm = root.getSiteManager()
>>> conn.close()

A DatabaseOpenedWithRoot is generated with the database.

>>> from zope.component.eventtesting import getEvents
>>> [event] = getEvents(zope.processlifetime.IDatabaseOpenedWithRoot)
>>> event.database is db
True

Generally, startup code that expects the root object and site to have been created will want to subscribe to this event, not IDataBaseOpenedEvent.

The subscriber generates the event whether or not the root had to be set up:

>>> bootstrap.bootStrapSubscriber(zope.processlifetime.DatabaseOpened(db))
>>> [e, event] = getEvents(zope.processlifetime.IDatabaseOpenedWithRoot)
>>> event.database is db
True

Check the Security Policy

When the security policy got refactored to be really pluggable, the inclusion of the security policy configuration was moved to the very top level, to site.zcml. This happened in r24770, after ZopeX3 3.0 was released, but before 3.1.

Now the maintainers of existing 3.0 sites need to manually update their site.zcml to include securitypolicy.zcml while upgrading to 3.1. See also http://www.zope.org/Collectors/Zope3-dev/381 .

>>> from __future__ import print_function
>>> from zope.testing.loggingsupport import InstalledHandler
>>> handler = InstalledHandler('zope.app.appsetup')

If the security policy is unset from the default ParanoidSecurityPolicy, we get a warning:

>>> from zope.app.appsetup.bootstrap import checkSecurityPolicy
>>> event = object()
>>> checkSecurityPolicy(event)
>>> print(handler)
zope.app.appsetup WARNING
  Security policy is not configured.
Please make sure that securitypolicy.zcml is included in site.zcml immediately
before principals.zcml

However, if any non-default security policy is installed, no warning is emitted:

>>> from zope.security.management import setSecurityPolicy
>>> defaultPolicy = setSecurityPolicy(object())
>>> handler.clear()
>>> checkSecurityPolicy(event)
>>> print(handler)
<BLANKLINE>

Clean up:

>>> handler.uninstall()

Debug console

The debug console lets you have a Python prompt with the full Zope environment loaded (which includes the ZCML configuration, as well as an open database connection).

Let’s define a helper to run the debug script and trap SystemExit exceptions that would otherwise hide the output

>>> from __future__ import print_function
>>> import sys
>>> from zope.app.appsetup import debug
>>> def run(*args):
...     sys.argv[0] = 'debug'
...     sys.stderr = sys.stdout
...     try:
...         debug.main(args)
...     except SystemExit as e:
...         print("(exited with status %d)" % e.code)

If you call the script with no arguments, it displays a brief error message on stderr

>>> run()
Error: please specify a configuration file
For help, use debug -h
(exited with status 2)

We need to pass a ZConfig configuration file as an argument

>>> run('-C', 'test.conf')
The application root is known as `root`.

Now you have the root object from the open database available as a global variable named ‘root’ in the __main__ module:

>>> main_module = sys.modules['__main__']
>>> main_module.root            # doctest: +ELLIPSIS
<zope.site.folder.Folder object at ...>

and we have asked Python to enter interactive mode by setting the PYTHONINSPECT environment variable

>>> import os
>>> os.environ.get('PYTHONINSPECT')
'true'

We have to do extra work to honor the PYTHONSTARTUP environment variable:

>>> pythonstartup = os.path.join(os.path.dirname(debug.__file__),
...                              'testdata', 'pythonstartup')
>>> os.environ['PYTHONSTARTUP'] = pythonstartup
>>> run('-C', 'test.conf')
The application root is known as `root`.

You can see that our pythonstartup file was executed because it changed the prompt

>>> sys.ps1
'debug> '

Product-specific configuration

The product module of this package provides a very simple way to deal with what has traditionally been called “product configuration”, where “product” refers to the classic Zope 2 notion of a product.

The configuration schema for the application server allows named <product-config> sections to be added to the configuration file, and product code can use the API provided by the module to retrieve configuration sections for given names.

There are two public functions in the module that should be used in normal operations, and additional functions and a class that can be used to help with testing:

>>> from __future__ import print_function
>>> from zope.app.appsetup import product

Let’s look at the helper class first, since we’ll use it in describing the public (application) interface. We’ll follow that with the functions for normal operation, then the remaining test-support functions.

Faux configuration object

The FauxConfiguration class constructs objects that behave like the ZConfig section objects to the extent needed for the product configuration API. These will be used here, and may also be used to create configurations for testing components that consume such configuration.

The constructor requires two arguments: the name of the section, and a mapping of keys to values that the section should provide. Let’s create a simple example:

>>> one = product.FauxConfiguration("one", {})
>>> one.getSectionName()
'one'
>>> one.mapping
{}

Providing a non-empty set of key/value pairs trivially behaves as expected:

>>> two = product.FauxConfiguration("two", {"abc": "def"})
>>> two.getSectionName()
'two'
>>> two.mapping
{'abc': 'def'}

Application API

There are two functions in the application interface for this module. One is used by the configuration provider, and the other is used by the consumer.

The provider’s API takes a sequence of configuration objects that conform to the behaviors exhibited by the default ZConfig section objects. Since the FauxConfiguration class provides these behaviors, we can easily see how this can be used:

>>> product.setProductConfigurations([one, two])

Now that we’ve established some configuration, we want to be able to use it. We do this using the getProductConfiguration() function. This function takes a name and returns a matching configuration section if there is one, of None if not:

>>> product.getProductConfiguration("one")
{}
>>> product.getProductConfiguration("not-there") is None
True

Note that for a section that exists, only the internal mapping is provided, not the containing section object. This is a historical wart; we’ll just need to live with it until new APIs are introduced.

Setting the configuration a second time will overwrite the prior configuration; sections previously available will no longer be:

>>> product.setProductConfigurations([two])
>>> product.getProductConfiguration("one") is None
True

The new sections are available, as expected:

>>> product.getProductConfiguration("two")
{'abc': 'def'}

Test support functions

Additional functions are provided that make it easier to manage configuration state in testing.

The first can be used to provide configuration for a single name. The function takes a name and either a configuration mapping or None as arguments. If None is provided as the second argument, any configuration settings for the name are removed, if present. If the second argument is not None, it will be used as the return value for getProductConfiguration for the given name.

>>> product.setProductConfiguration("first", None)
>>> print(product.getProductConfiguration("first"))
None
>>> product.setProductConfiguration("first", {"key": "value1"})
>>> product.getProductConfiguration("first")
{'key': 'value1'}
>>> product.setProductConfiguration("first", {"key": "value2"})
>>> product.getProductConfiguration("first")
{'key': 'value2'}
>>> product.setProductConfiguration("first", {"alt": "another"})
>>> product.getProductConfiguration("first")
{'alt': 'another'}
>>> product.setProductConfiguration("second", {"you": "there"})
>>> product.getProductConfiguration("first")
{'alt': 'another'}
>>> product.getProductConfiguration("second")
{'you': 'there'}
>>> product.setProductConfiguration("first", None)
>>> print(product.getProductConfiguration("first"))
None

The other two functions work in concert, saving and restoring the entirety of the configuration state.

Our current configuration includes data for the “second” key, and none for the “first” key:

>>> print(product.getProductConfiguration("first"))
None
>>> print(product.getProductConfiguration("second"))
{'you': 'there'}

Let’s save this state:

>>> state = product.saveConfiguration()

Now let’s replace the kitchen sink:

>>> product.setProductConfigurations([
...     product.FauxConfiguration("x", {"a": "b"}),
...     product.FauxConfiguration("y", {"c": "d"}),
...     ])
>>> print(product.getProductConfiguration("first"))
None
>>> print(product.getProductConfiguration("second"))
None
>>> product.getProductConfiguration("x")
{'a': 'b'}
>>> product.getProductConfiguration("y")
{'c': 'd'}

The saved configuration state can be restored:

>>> product.restoreConfiguration(state)
>>> print(product.getProductConfiguration("x"))
None
>>> print(product.getProductConfiguration("y"))
None
>>> print(product.getProductConfiguration("first"))
None
>>> print(product.getProductConfiguration("second"))
{'you': 'there'}

There’s an additional function that can be used to load product configuration from a file object; only product configuration components are accepted. The function returns a mapping of names to configuration objects suitable for passing to setProductConfiguration. Using this with setProductConfigurations would require constructing FauxConfiguration objects.

Let’s create some sample configuration text:

>>> product_config = u'''
... <product-config product1>
...   key1 product1-value1
...   key2 product1-value2
... </product-config>
...
... <product-config product2>
...   key1 product2-value1
...   key3 product2-value2
... </product-config>
... '''

We can now load the configuration using the loadConfiguration function:

>>> import io
>>> import pprint
>>> sio = io.StringIO(product_config)
>>> config = product.loadConfiguration(sio)
>>> pprint.pprint(config, width=1)
{u'product1': {'key1': 'product1-value1',
               'key2': 'product1-value2'},
 u'product2': {'key1': 'product2-value1',
               'key3': 'product2-value2'}}

Extensions that provide product configurations can be used as well:

>>> product_config = u'''
... %import zope.app.appsetup.testproduct
...
... <testproduct foobar>
... </testproduct>
...
... <testproduct barfoo>
...   key1 value1
...   key2 value2
... </testproduct>
... '''
>>> sio = io.StringIO(product_config)
>>> config = product.loadConfiguration(sio)
>>> pprint.pprint(config, width=1)
{u'barfoo': {'key1': 'value1',
             'key2': 'value2',
             'product-name': u'barfoo'},
 u'foobar': {'product-name': u'foobar'}}

Changelog

4.0.0 (2016-08-08)

  • Add dependency on zdaemon (split off from ZODB).
  • Claim support for Python 3.4, 3.5 and PyPy which requires zope.app.publication >= 4.0.
  • Drop Python 2.6 support.

4.0.0a1 (2013-03-03)

  • Added support for Python 3.3.
  • Replaced deprecated zope.interface.implements usage with equivalent zope.interface.implementer decorator.
  • Dropped support for Python 2.4 and 2.5.

3.16.0 (2011-01-27)

  • Added stacking of storages for layer/test level setup separation in derived ZODBLayers.

3.15.0 (2010-09-25)

  • Updated tests to run with zope.testing >= 3.10, requiring at least this version and zope.testrunner.
  • Switch IErrorReportingUtility copy_to_zlog field to True.
  • Using Python’s doctest module instead of depreacted zope.testing.doctest.

3.14.0 (2010-04-13)

  • Made zope.testing an optional (test) dependency.
  • Removed test dependency on zope.app.testing.

3.13.0 (2009-12-24)

  • Import hooks functionality from zope.component after it was moved there from zope.site.
  • Import ISite from zope.component after it was moved there from zope.location. This lifts the dependency on zope.location.
  • Added missing install dependency on zope.testing.

3.12.0 (2009-06-20)

  • Using zope.processlifetime interfaces and implementations directly instead of BBB imports from zope.app.appsetup.
  • Got rid of depencency on zope.app.component.
  • Got rid of test dependency on zope.app.security.

3.11 (2009-05-13)

  • Event interfaces / implementations moved to zope.processlifetime, version 1.0. Depend on this package, and add BBB imports.

3.10.1 (2009-03-31)

  • Fixed a DeprecationWarning introduced in 3.10.0.
  • Added doctests to long description to show up at pypi.

3.10.0 (2009-03-19)

  • Finally deprecate the “asObject” argument of helper functions in the zope.app.appsetup.bootstrap module. If your code uses any of these functions, please remove the “asObject=True” argument passing anywhere, because the support for that argument will be dropped soon.
  • Move session utility bootstrapping logic from zope.session into this package. This removes a dependency from zope.session to this package.
  • Remove one more deprecated function.

3.9.0 (2009-01-31)

  • Use zope.site instead of zope.app.folder and zope.app.component.
  • Use zope.container instead of zope.app.container.
  • Move error log bootstrapping logic from zope.error into this package. This removes a dependency from zope.error to this package. Also added a test for bootstrapping the error log here, which was missing in zope.error.

3.8.0 (2008-08-25)

  • Feature: Developed an entry point that allows you to quickly bring up an application instance for debugging purposes. (Implemented by Marius Gedminas and Stephan Richter.)

3.7.0 (2008-08-19)

  • Added .product.loadConfiguration test-support function; loads product configuration (only) from a file object, allowing test code (including setup) to make use of the same configuration schema support used by normal startup.

3.6.0 (2008-07-23)

  • Added additional test support functions to set the configuration for a single section, and save/restore the entire configuration.

3.5.0 (2008-06-17)

  • Added helper class for supporting product configuration tests.
  • Added documentation for the product configuration API, with tests.

3.4.1 (2007-09-27)

  • Egg was faulty, re-released.

3.4.0 (2007-09-25)

  • Initial documented release.
  • Reflect changes form zope.app.error refactoring.
 
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