4a726d124a
This adds the base Context class for striker, along with several support functions and classes. This also settles on the Apache v2 license. Related to RM7484.
124 lines
5.2 KiB
Python
124 lines
5.2 KiB
Python
# Copyright 2014 Rackspace
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the
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# License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing,
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# software distributed under the License is distributed on an "AS
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# IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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# express or implied. See the License for the specific language
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# governing permissions and limitations under the License.
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from striker.core import environment
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class Context(object):
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"""
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Execution context. Objects of this class contain all the basic
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configuration data needed to perform a task.
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"""
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def __init__(self, workspace, config, logger,
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debug=False, dry_run=False, **extras):
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"""
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Initialize a ``Context`` object.
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:param workspace: The name of a temporary working directory.
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The directory must exist.
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:param config: An object containing configuration data. The
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object should support read-only attribute-style
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access to the configuration settings.
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:param logger: An object compatible with ``logging.Logger``.
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This will be used by all consumers of the
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``Context`` to emit logging information.
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:param debug: A boolean, defaulting to ``False``, indicating
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whether debugging mode is active.
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:param dry_run: A boolean, defaulting to ``False``, indicating
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whether permanent changes should be effected.
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This should be used to control whether files
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are uploaded, for instance.
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:param extras: Keyword arguments specifying additional data to
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be stored in the context. This could be, for
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instance, account data.
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"""
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# Store basic context data
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self.workspace = workspace
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self.config = config
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self.logger = logger
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self.debug = debug
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self.dry_run = dry_run
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# Extra data--things like accounts
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self._extras = extras
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# Environment
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self._environ = None
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def __getattr__(self, name):
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"""
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Provides access to the extra data specified to the constructor.
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:param name: The name of the extra datum to retrieve.
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:returns: The value of the extra datum.
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"""
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if name not in self._extras:
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raise AttributeError("'%s' object has no attribute '%s'" %
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(self.__class__.__name__, name))
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return self._extras[name]
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@property
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def environ(self):
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"""
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Access the environment. The environment is a dictionary of
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environment variables, but it is also a callable that can be
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used to invoke shell commands.
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:param cmd: The command to execute, as either a bare string or
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a list of arguments. If a string, it will be
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split into a list using ``shlex.split()``. Note
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that use of bare strings for this argument is
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discouraged.
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:param capture_output: If ``True``, standard input and output
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will be captured, and will be available
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in the result. Defaults to ``False``.
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Note that this is treated as implicitly
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``True`` if the ``retry`` parameter is
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provided.
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:param cwd: Gives an alternate working directory from which to
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run the command.
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:param do_raise: If ``True`` (the default), an execution
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failure will raise an exception.
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:param retry: If provided, must be a callable taking one
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argument. Will be called with an instance of
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``ExecResult``, and can return ``True`` to
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indicate that the call should be retried.
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Retries are performed with an exponential
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backoff controlled by ``max_tries``.
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:param max_tries: The maximum number of tries to perform
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before giving up, if ``retry`` is specified.
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Retries are performed with an exponential
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backoff: the first try is performed
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immediately, and subsequent tries occur
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after a sleep time that starts at one second
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and is doubled for each try.
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:returns: An ``ExecResult`` object containing the results of
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the execution. If the return code was non-zero and
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``do_raise`` is ``True``, this is the object that
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will be raised.
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"""
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# Construct the environment if necessary
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if self._environ is None:
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self._environ = environment.Environment(self.logger)
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return self._environ
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