Merge "Add Watcher Continuosly Optimization spec"

specs/newton/approved/continuously-optimization.rst

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+=============================================
+Watcher Continuous Optimization
+=============================================
+
+https://blueprints.launchpad.net/watcher/+spec/continuously-optimization
+
+
+Problem description
+===================
+
+`Cluster`_ can be optimized by different `Strategies`_ only when they have
+been triggered by `Administrator`_. Launching a recommended `Action Plan`_
+manually is not always suitable since state of cluster is constantly changing.
+It would be better to have two ways of launching audit: either by triggering
+it manually or by launching it periodically.
+We propose to include continuous optimization as continuous type of
+audit object in Watcher Project.
+
+The main purpose of this change is to design and implement active mode of
+Watcher's audit.
+
+This specification relates to blueprint:
+https://blueprints.launchpad.net/watcher/+spec/continuously-optimization
+
+Use Cases
+---------
+
+As the Administrator I want to create `Audit`_ with CONTINUOUS type.
+I specify periodic time with --period parameter (in seconds) to run audit
+every 600 seconds. Running audit will create action plan every 600 seconds.
+
+Project Priority
+----------------
+
+Not relevant because Watcher is not in the big tent so far.
+
+
+Proposed change
+===============
+
+To perform audits with continuous type we can use periodic_task decorator
+from oslo_service module on 'launch_audits_periodically' method. This method
+gets continuous type audits with (PENDING, ONGOING) states. If some
+of them are not in audits_to_launch list we add them to that list and to the
+ThreadPoolExecutor. Once audit is added to thread, this thread is going to
+sleep for PERIOD seconds. After this audit will be executed and UUID of audit
+will be removed from audits_to_launch list.
+To keep track of the triggered audit, notification has to be pushed on
+the message bus every time the audit is re-triggered.
+When a new action plan is proposed, Watcher should cancel all the previously
+generated action plans (and actions) with same Audit Template become obsolete
+and therefore their state should be changed to CANCELLED.
+
+Alternatives
+------------
+
+* To use Congress to automatically trigger audits when some conditions are met.
+* To use a cronjob which triggers new audit regularly via python-watcherclient.
+
+Data model impact
+-----------------
+
+There must be new field in Audit model: integer 'period'. 'period' field has
+3600 by default.
+
+REST API impact
+---------------
+
+period's field has to be added as Audit attribute.
+
+Security impact
+---------------
+
+None expected.
+
+Notifications impact
+--------------------
+
+None expected.
+
+Other end user impact
+---------------------
+
+Support for 'period' field must be added to the python-watcherclient and
+to the watcher-dashboard.
+
+Performance Impact
+------------------
+
+No specific performance impact is expected.
+
+Other deployer impact
+---------------------
+
+No specific deployer impact is envisaged.
+
+Developer impact
+----------------
+
+This will not impact other developers working on OpenStack.
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  Alexander Chadin <alexchadin>
+Other contributors:
+  Vladimir Ostroverkhov <Ostroverkhov>
+
+Work Items
+----------
+
+* Add support for periodic_task decorator.
+* Implement PeriodicAuditHandler that manages DefaultAuditHandler.
+* Implement method 'execute' that runs audits periodically.
+* Adapt API to support period field.
+* Make some changes to python-watcherclient to add support for period argument.
+* Add changes to watcher-dashboard to support CONTINUOUS type.
+* Implement appropriate unit tests to test various scenarios.
+
+Dependencies
+============
+
+There are no dependencies.
+
+Testing
+=======
+
+Appropriate unit tests will be adapted to new changes.
+
+Documentation Impact
+====================
+
+It will be necessary to add new content relating to this change.
+
+References
+==========
+
+No references.
+
+History
+=======
+
+No history.
+
+
+.. _Strategies: https://factory.b-com.com/www/watcher/doc/watcher/glossary.html#strategy
+.. _Administrator: https://factory.b-com.com/www/watcher/doc/watcher/glossary.html#administrator
+.. _Audit: https://factory.b-com.com/www/watcher/doc/watcher/glossary.html#audit
+.. _Action Plan: https://factory.b-com.com/www/watcher/doc/watcher/glossary.html#action-plan
+.. _Cluster: https://factory.b-com.com/www/watcher/doc/watcher/glossary.html#cluster