58ea85c852
This documentation describes step-by-step the process for implementing a new action in Watcher. Change-Id: I978b81cdf9ac6dcf43eb3ecbb79ab64ae4fd6f72 Closes-Bug: #1534639
117 lines
3.6 KiB
Python
117 lines
3.6 KiB
Python
# -*- encoding: utf-8 -*-
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# Copyright (c) 2015 b<>com
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#
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# Authors: Jean-Emile DARTOIS <jean-emile.dartois@b-com.com>
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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 License.
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# 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, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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import abc
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import six
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from watcher.common import clients
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@six.add_metaclass(abc.ABCMeta)
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class BaseAction(object):
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# NOTE(jed) by convention we decided
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# that the attribute "resource_id" is the unique id of
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# the resource to which the Action applies to allow us to use it in the
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# watcher dashboard and will be nested in input_parameters
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RESOURCE_ID = 'resource_id'
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def __init__(self, osc=None):
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""":param osc: an OpenStackClients instance"""
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self._input_parameters = {}
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self._osc = osc
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@property
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def osc(self):
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if not self._osc:
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self._osc = clients.OpenStackClients()
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return self._osc
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@property
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def input_parameters(self):
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return self._input_parameters
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@input_parameters.setter
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def input_parameters(self, p):
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self._input_parameters = p
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@property
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def resource_id(self):
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return self.input_parameters[self.RESOURCE_ID]
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@abc.abstractmethod
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def execute(self):
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"""Executes the main logic of the action
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This method can be used to perform an action on a given set of input
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parameters to accomplish some type of operation. This operation may
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return a boolean value as a result of its execution. If False, this
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will be considered as an error and will then trigger the reverting of
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the actions.
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:returns: A flag indicating whether or not the action succeeded
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:rtype: bool
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"""
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raise NotImplementedError()
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@abc.abstractmethod
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def revert(self):
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"""Revert this action
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This method should rollback the resource to its initial state in the
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event of a faulty execution. This happens when the action raised an
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exception during its :py:meth:`~.BaseAction.execute`.
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"""
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raise NotImplementedError()
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@abc.abstractmethod
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def precondition(self):
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"""Hook: called before the execution of an action
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This method can be used to perform some initializations or to make
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some more advanced validation on its input parameters. So if you wish
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to block its execution based on this factor, `raise` the related
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exception.
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"""
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raise NotImplementedError()
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@abc.abstractmethod
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def postcondition(self):
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"""Hook: called after the execution of an action
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This function is called regardless of whether an action succeded or
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not. So you can use it to perform cleanup operations.
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"""
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raise NotImplementedError()
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@abc.abstractproperty
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def schema(self):
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"""Defines a Schema that the input parameters shall comply to
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:returns: A schema declaring the input parameters this action should be
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provided along with their respective constraints
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:rtype: :py:class:`voluptuous.Schema` instance
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"""
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raise NotImplementedError()
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def validate_parameters(self):
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self.schema(self.input_parameters)
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return True
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