dc55d63222
This patch set fixes all specification warnings and set warning-is-error flag to True. Change-Id: I9a6132cfd0d010db21c148be53b6bb5523eb6f5c
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4.7 KiB
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182 lines
4.7 KiB
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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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Add support to cancel execution of Action Plan
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==============================================
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https://blueprints.launchpad.net/watcher/+spec/cancel-action-plan
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Problem description
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===================
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A Cloud `Administrator`_ may want to cancel the `action plan`_ execution for
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any reason. An Action Plan can be in execution from long time and a cloud
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Administrator may want to execute the actions manually or want to fulfill the
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optimization requirements by some other methods.
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As of now Administrator can update the action plan state to **CANCELLED** but
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there is no action taken by Watcher to cancel the action plan. It only updates
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the action plan state to **CANCELLED**.
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It should be possible to **CANCEL** execution of the action plan by Watcher.
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Use Cases
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----------
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As a Watcher Administrator, I want Watcher to CANCEL the action plan that is
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in ONGOING state for a long time.
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As a Watcher Administrator, I want to CANCEL any action plan that is
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accidentally launched.
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As a Watcher Administrator, I want to CANCEL the action plan because my
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optimization requirements have been met.
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Proposed change
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===============
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* Add new state **CANCELLING** for the **Action Plan**.
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* CANCELLING, when watcher-api receives request from cloud admin to cancel
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the **ONGOING** action plan. When watcher-applier successfully executed
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the cancel request it will update the action plan state to **CANCELLED**.
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When watcher-applier failed to complete the action plan cancel request, it
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will update the action plan state to **FAILED**.
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* Add new states **CANCELLING**, **CANCELLED** to **Action**.
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* CANCELLING, when watcher-applier cancel an ONGOING action.
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* CANCELLED, when watcher-applier cancel a PENDING action. when
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watcher-applier successfully completed cancel of ONGOING action.
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* Add a new command **watcher actionplan cancel** in watcher-client to cancel
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the action plan.
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* Modify the state machine for action plan to add new actions plan state and
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transitions.
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* Modify the state machine for action to add new actions states and
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transitions.
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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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https://blueprints.launchpad.net/watcher/+spec/notifications-actionplan-cancel
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Other end user impact
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---------------------
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A new command **watcher actionplan cancel** will be added to cancel the action
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plan.
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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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Watcher cannot guarantee about the cluster state after cancelling the ongoing
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optimizations.
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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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<adi-sky17>
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Work Items
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----------
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* Implementation for action plan cancel will be done by using taskflow. When a
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running engine receives an exception, it stops execution and calls revert
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method for all the tasks(actions) added in the flow. In the revert method of
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action, current action state is checked and based on the action state
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(PENDING, ONGOING, SUCCEEDED) revert method will execute defined steps.
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.. code-block:: python
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e.g. if action_state is PENDING:
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# update action_state to CANCELLED
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if action_state is ONGOING:
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# call abort_action
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if action state is SUCCEEDED:
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# do nothing
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* Before starting any new action watcher-applier will check for the state of
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action plan, if its state is updated to CANCELLING it will trigger an
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exception "ActionPlanCancel" to the taskflow engine and taskflow engine will
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call revert method of all tasks (actions) in reverse manner, keeping the
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dependencies intact.
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Dependencies
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============
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For action plan cancel operation we need to call Abort API for **ONGOING**
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actions.
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The abort API of live migration is available.
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https://blueprints.launchpad.net/nova/+spec/abort-live-migration
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The abort API for cold migration is under development.
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https://blueprints.launchpad.net/nova/+spec/abort-cold-migration
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Testing
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=======
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The unit and tempest tests will have to be updated.
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Documentation Impact
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====================
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Need to update the **Action Plan State Machine** in the architecture
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documentation.
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Need to add the **Action State Machine** in the architecture documentation.
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References
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==========
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.. _Administrator: https://docs.openstack.org/developer/watcher/glossary.html#administrator-definition
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.. _action plan: https://docs.openstack.org/developer/watcher/glossary.html#action-plan
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History
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=======
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None
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