Added a spec for supporting deduced alarms

Change-Id: Id9f69ef2acb79e77ad60a5d2324711ff1e03fc20

specs/mitaka/vitrage-support-deduced-alarms.rst

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+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+==================================
+Vitrage Support for Deduced Alarms
+==================================
+
+https://blueprints.launchpad.net/vitrage/+spec/support-deduced-alarms
+
+Vitrage should support raising deduced alarms.
+When an alarm is raised on a certain resource, we might conclude that it results in problems in other related
+resources. In this case, we would like to raise deduced alarms on these other resources, even if we got no indication
+of a problem from other sources of information.
+
+Problem description
+===================
+
+There are cases where we know that a failure in one resource should result in problems in other resources. For example,
+high CPU load on a host may cause suboptimal performance of all instances running on this host, thus performance
+problems in the applications running on these instances. As far as Nova is concerned, all instances are up and
+running, and there is no indication of a problem.
+
+
+Proposed change
+===============
+
+The Vitrage Evaluator serves as workflow manager controlling the analysis and activation of templates and execution
+of template actions. One of its responsibilities is to listen to changes in Vitrage Graph, and upon a change execute
+the matching templates. This is a general mechanism that should work for all kinds of templates and perform several
+kinds of actions.
+
+The aim of this blueprint is to make sure deduced alarms functionality works properly end to end.
+
+Whenever a new alarm is raised, Vitrage Graph is updated with a new vertex for this alarm, connected to the relevant
+resource. Then, the vitrage evaluator engine looks for templates that could match this new alarm. If deduced alarms
+templates are found, the engine will try to find a full match for the entire template in Vitrage Graph. If found,
+the engine will ask the notifier to raise new alarms according to the template.
+
+
+Example for a graph with deduced alarms:
+
+::
+
+ Original alarm:
+ +-----------+               +------------+
+ |Host High  |     on        |            |
+ |CPU load   | +-----------> |  Host      |
+ |           |               |            |
+ +-----------+               +-----+------+
+                                   |
+                                   | contains
+ Deduced alarm                     |
+ to raise:                         |
+ +-----------+               +-----v------+
+ |Instance   |     on        |            |
+ |Suboptimal | +-----------> |  Instance  |
+ |Performance|               |            |
+ +-----------+               +------------+
+
+
+
+
+Alternatives
+------------
+
+None
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+None
+
+Security impact
+---------------
+
+None
+
+Pipeline impact
+---------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+Performance/Scalability Impacts
+-------------------------------
+
+None
+
+Other deployer impact
+---------------------
+
+None
+
+Developer impact
+----------------
+
+None
+
+Horizon impact
+--------------
+
+None
+
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+    ifat_afek <ifat.afek@alcatel-lucent.com>
+
+Work Items
+----------
+
+The blueprint includes:
+
+- Define the exact syntax for deduced alarms templates
+- Call the notifier to raise alarms
+
+
+Future lifecycle
+================
+
+None
+
+Dependencies
+============
+
+- Vitrage Graph
+- Vitrage Engine
+- Vitrage Notifier
+
+Testing
+=======
+
+This change needs to be tested by unit tests.
+
+Documentation Impact
+====================
+
+None
+
+References
+==========
+
+https://wiki.openstack.org/wiki/Vitrage
+