Momgodb-events-feature specs

The purpose of this bp is to implement event feature on MongoDB and DB2

Implements blueprint mongodb-events-feature

Change-Id: Id8174b4889f85d07e5ade8419664b52f4c856b2e

specs/juno/mongodb-events-feature.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
+
+===============================
+Enable event feature on MongoDB
+===============================
+
+https://blueprints.launchpad.net/ceilometer/+spec/mongodb-events-feature
+
+Events feature was implemented on SQLAlchemy and HBase backends. And now it is
+necessary to extend it on MongoDB and DB2.
+
+Problem description
+===================
+
+The usecase is to store events in database (MongoDB or DB2) and to get
+events (event's types, traits, trait's types) from this database.
+
+The main idea is to implement event feature in way like it was done on
+other drivers (SQLAlchemy and HBase).
+
+Usecases:
+
+- to get all events that were created in a specified period of time
+
+- to get events by event's type
+
+- to get events by event's message id
+
+- to get events by trait's description, type, and value
+
+- to get all event's types that were stored
+
+- to get all trait types belonging to specific event type
+
+- to get all traits that could be found in specific event's type, and
+  optionally with specific trait type.
+
+Proposed change
+===============
+
+Add new methods in ceilometer.storage.pymongo_base.py for storing and getting
+events from database. Basing on events implementation that have been already
+done we should create next methods:
+
+1. record_event -- method for storing collected events into MongoDB and DB2
+
+2. get_events -- method for getting events from MongoDB and DB2 with specified
+   filters:
+   - period of event's generation time
+   - event's type
+   - event's message id
+   - trait's description, type, and value (here should be taken into account
+   possible operations on values, for ex: <lt, le, eq, ne, ge, gt>)
+
+3. get_event_types -- method for getting all event's types that were stored in
+   database.
+
+4. get_trait_types -- method returns all trait types for all stored event
+   types or only for one event's type if it is specified.
+
+5. get_traits -- method returns all traits for certain event type, or traits
+   for specified trait's type if type is defined.
+
+Alternatives
+------------
+
+None
+
+Data model impact
+-----------------
+
+We will need to add new collection into MongoDB and DB2 for events
+
+Collection:
+
+- events
+    - _id: uuid of event (Event.message_id)
+    - event_type: description of event's type
+    - timestamp: time stamp of event generation
+    - traits: [array of {trait_name: string, trait_type: integer,
+              trait_value: data}]
+
+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
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  * idegtiarov
+
+Ongoing maintainer:
+  * idegtiarov
+
+Work Items
+----------
+
+* Create new method for event feature implementation on MongoDB and DB2
+* Test method in unit tests
+
+Future lifecycle
+================
+
+None
+
+Dependencies
+============
+
+None
+
+Testing
+=======
+
+This code will be tested in unit tests for event feature
+
+Documentation Impact
+====================
+
+None
+
+References
+==========
+
+None
+