165 lines
3.8 KiB
ReStructuredText
165 lines
3.8 KiB
ReStructuredText
..
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This work is licensed under a Creative Commons Attribution 3.0 Unported
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License.
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http://creativecommons.org/licenses/by/3.0/legalcode
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============================
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Make default Planner generic
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============================
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https://blueprints.launchpad.net/watcher/+spec/configurable-weights-default-planner
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Problem description
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===================
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Watcher provides a very modular architecture that currently allows anyone
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to provide custom plugins:
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- Strategy
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- Planner
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- Action
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- Workflow Engine
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In most of the above, their related implementation(s) are generic enough so
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that they can work with any 3rd party plugin out of the box.
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However, this is currently not the case for the `defaultplanner`_ which
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defines a hardcoded set of priorities for each action type.
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Hence, this means that adding a new `Action`_ via an action plugin and
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reference it in a strategy would result in an error and the only solution
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is to create a planner plugin that would adapt to this new action.
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This is not very user friendly for the Watcher users because this means that
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every time someone adds a new action, the source code of the
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planner will have to be amended.
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Use Cases
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----------
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As an administrator, I would like to be able to add a new `Action`_ without
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having to amend the source code of the `defaultplanner`_.
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Project Priority
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----------------
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* Medium
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Proposed change
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===============
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This specification suggests modifying the DefaultPlanner class
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``watcher/decision_engine/planner/default.py`` in order to avoid having to
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implement a new planner whenever adding a new action plugin to
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the mix.
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A simple solution to this would be to leverage the `plugins-parameters`_
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blueprint so that we can configure weights via the configuration file.
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Currently in watcher, the weights are defined as below:
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::
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priorities = {
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'nop': 0,
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'sleep': 1,
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'change_nova_service_state': 2,
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'migrate': 3
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}
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We have to replace this by the code below :
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::
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self.weights_dict = {'nop': 0,
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'sleep': 1,
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'change_nova_service_state': 2,
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'migrate':3}
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def get_config_opts(self):
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return [
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cfg.DictOpt('weights', help="These weights are used to schedule
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the Actions.",
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default=self.weights_dict),
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]
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Alternatives
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------------
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None
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Data model impact
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-----------------
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None
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REST API impact
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---------------
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None
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Security impact
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---------------
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None
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Notifications impact
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--------------------
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None
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Other end user impact
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---------------------
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The user will have to modify the configurable file and reboot
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the decision engine.
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Performance Impact
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------------------
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None
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Other deployer impact
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---------------------
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We are adding a new field in the configuration file. So, we should revisit the
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puppet scripts.
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Developer impact
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----------------
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None
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Implementation
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==============
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Assignee(s)
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-----------
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Primary assignee:
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Jinquan Ni <ni.jinquan@zte.com.cn>
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Work Items
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----------
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* Replace the storage of the weights in the default planner
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* Update the documentation
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* add unit tests
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Dependencies
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============
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None
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Testing
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=======
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* Unit tests will be added to validate these modifications.
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Documentation Impact
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====================
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Update the `defaultplanner`_ documentations to now mention that the weights of
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the planner can be specified in the configuration file.
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References
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==========
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.. _defaultplanner: https://github.com/openstack/watcher/blob/master/watcher/decision_engine/planner/default.py#L38
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.. _Action: https://factory.b-com.com/www/watcher/doc/watcher/glossary.html#action
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.. _plugins-parameters: https://blueprints.launchpad.net/watcher/+spec/plugins-parameters
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.. _base planner: https://github.com/openstack/watcher/blob/master/watcher/decision_engine/planner/base.py#L57
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History
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=======
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None |