Neutron Resource Cleanup spec

Implements blueprint neutron-resource-cleanup

Change-Id: I7937426a44be5f6b3d0310ca11fee4ed9debf8d9

specs/7.0/neutron-resource-cleanup.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
+
+========================
+Neutron Resource Cleanup
+========================
+
+Include the URL of your launchpad blueprint:
+
+https://blueprints.launchpad.net/fuel/+spec/neutron-resource-cleanup
+
+On controllers Neutron network resources such as namespaces, interfaces,
+OVS ports and processes are managed in two unrelated parts of code:
+Neutron agents and OCF scripts including `q-agent-cleanup` script.
+The goal is to move all responsibility to a single point - Neutron.
+
+
+Problem description
+===================
+
+Right now resource cleanup is performed by external script provided by Fuel
+(`q-agent-cleanup`). The script lives in `fuel-library` repo and it may be
+changed to re-use code from Neutron. Ideally all cleanup code should belong to
+Neutron agents as they currently able to manage namespaces, network interfaces,
+OVS ports and processes.
+
+The proposal in inspired by issues:
+
+* Clearing up the large number of network namespaces is very time consuming.
+  Pacemaker has very strict timeout management and if the operation doesn't
+  fit the whole resource may turn into unmanaged state
+  (https://bugs.launchpad.net/fuel/+bug/1436414).
+
+* Restart of a particular agent is performed via banning and clearing the
+  associated pacemaker resource. As result all network namespaces are dropped
+  and then created again causing traffic interruptions
+  (https://bugs.launchpad.net/fuel/+bug/1464817).
+
+* Code defects in `q-agent-cleanup`
+  (https://bugs.launchpad.net/fuel/+bug/1434196)
+
+
+Proposed change
+===============
+
+The proposed change is mostly related to code refactoring and optimization. It
+doesn't suggest changes in the architecture. OCF scripts will remain the
+entry-point for resource clean-up, however the code will move to Neutron.
+
+Step-by-step changes:
+ 1. Move `q-agent-cleanup` and the corresponding test into Neutron tree.
+    Add shell entry point into Neutron package.
+ 2. Refactor the code by re-using existing parts from Neutron. The CLI should
+    stay the same.
+ 3. Apply optimizations with replacing shell calls by iproute2 (native ovsdb if
+    applicable)
+
+
+Alternatives
+------------
+
+Initially we discussed the proposal to move the whole clean-up from OCF to
+Neutron agents. However there are cases where resources need to be cleared
+by external stuff.
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+None
+
+Upgrade impact
+--------------
+
+None
+
+Security impact
+---------------
+
+None
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+Performance Impact
+------------------
+
+Restart of agents should become faster when using native APIs instead of
+shell commands.
+
+Plugin impact
+-------------
+
+None
+
+Other deployer impact
+---------------------
+
+None
+
+
+Developer impact
+----------------
+
+Patches into `q-agent-cleanup` will be tested with Neutron infra, thus making
+changes less risky.
+
+Infrastructure impact
+---------------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  shakhat
+
+Other contributors:
+  skolekonov
+  kkuznetsova
+
+Work Items
+----------
+
+* Implementation
+
+    * Move `q-agent-cleanup` into Neutron tree
+    * Update Neutron package to install `q-agent-cleanup` shell utility
+    * Remove the old script from fuel-library tree
+    * Optimize resource cleanup to satisfy scale tests
+
+Dependencies
+============
+
+None
+
+Testing
+=======
+
+Revisit disaster tests, add new if needed. The following cases should be
+covered: restart of agent, death of agent, banning agent on a particular node.
+The same scenarios should be ran manually at scale on large numbers (thousands)
+of networks and routers.
+
+Documentation Impact
+====================
+
+None
+
+References
+==========
+
+None