TripleO DVR enablement

Outline for means to add the ability to configure enablement
of neutron distributed routers in the overcloud.

Added 'kilo' folder for this spec.

Change-Id: I52f213c794bc008c9b0a0fbcb4464cba9f309801

doc/source/index.rst

@@ -11,6 +11,7 @@ Juno approved specs:
    :maxdepth: 1
 
    specs/juno/*
+   specs/kilo/*
 
 ==================
 Indices and tables

specs/kilo/tripleo-enable-dvr.rst

@@ -0,0 +1,166 @@
+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+==========================================
+Enable Neutron DVR on overcloud in TripleO
+==========================================
+
+https://blueprints.launchpad.net/tripleo/+spec/support-neutron-dvr
+
+Neutron distributed virtual routing should be able to be configured in TripleO.
+
+
+Problem Description
+===================
+
+To be able to enable distributed virtual routing in Neutron there needs to be
+several changes to the current TripleO overcloud deployment.  The overcloud
+compute node(s) are constructed with the ``neutron-openvswitch-agent`` image
+element, which provides the ``neutron-openvswitch-agent`` on the compute node.
+In order to support distributed virtual routing, the compute node(s) must also
+have the ``neutron-metadata-agent`` and ``neutron-l3-agent`` installed. The
+installation of the ``neutron-l3-agent`` and ``neutron-dhcp-agent`` will need
+also to be decoupled.
+
+Additionally, for distributed virtual routing to be enabled, the
+``neutron.conf``, ``l3_agent.ini`` and ``ml2_conf.ini`` all need to have
+additional settings.
+
+Proposed Change
+===============
+
+In the tripleo-image-elements, move the current ``neutron-network-node`` element
+to an element named ``neutron-router``, which will be responsible for doing the
+installation and configuration work required to install the ``neutron-l3-agent``
+and the ``neutron-metadata-agent``. This ``neutron-router`` element will list
+the ``neutron-openvswitch-agent`` in its element-deps.  The ``neutron-network
+-node`` element will then become simply a 'wrapper' whose sole purpose is to list
+the dependencies required for a network node (neutron, ``neutron-dhcp-agent``,
+``neutron-router``, os-refresh-config).
+
+Additionally, in the tripleo-image-elements/neutron element, the
+``neutron.conf``, ``l3_agent.ini`` and ``plugins/ml2/ml2_conf.ini`` will be
+modified to add the configuration variables required in each to support
+distributed virtual routing (the required configuration variables are listed at
+https://wiki.openstack.org/wiki/Neutron/DVR/HowTo#Configuration).
+
+In the tripleo-heat-templates, the ``nova-compute-config.yaml``
+``nova-compute-instance.yaml`` and ``overcloud-source.yaml`` files will be
+modified to provide the correct settings for the new distributed virtual routing
+variables.  The enablement of distributed virtual routing will be determined by
+a 'NeutronDVR' variable which will be 'False' by default (distributed virtual
+routing not enabled) for backward compatibility, but can be set to 'True' if
+distributed virtual routing is desired.
+
+Lastly, the tripleo-incubator script ``devtest_overcloud.sh`` will be modified
+to: a) build the overcloud-compute disk-image with ``neutron-router`` rather
+than with ``neutron-openvswitch-agent``, and b) configure the appropriate
+parameter values to be passed in to the heat stack create for the overcloud so
+that distributed routing is either enabled or disabled.
+
+Alternatives
+------------
+
+We could choose to make no change to the ``neutron-router`` image-element and
+it can be included as well in the list of elements arguments to the disk image
+build for compute nodes.  This has the undesired effect of also
+including/configuring and starting the ``neutron-dhcp-agent`` on each compute
+node.  Alternatively, it is possible to keep the ``neutron-network-node``
+element as it is and create a ``neutron-router`` element which is a copy of
+most of the element contents of the ``neutron-network-node`` element but without
+the dependency on the ``neutron-dhcp-agent`` element.  This approach would
+introduce a significant amount of code duplication.
+
+Security Impact
+---------------
+
+Although TripleO installation does not use FWaaS, enablement of DVR currently
+is known to break FWaaS.
+See https://blueprints.launchpad.net/neutron/+spec/neutron-dvr-fwaas
+
+Other End User Impact
+---------------------
+
+The user will have the ability to set an environment variable during install
+which will determine whether distributed virtual routing is enabled or not.
+
+Performance Impact
+------------------
+
+None identified
+
+Other Deployer Impact
+---------------------
+
+The option to enable or disable distributed virtual routing at install time will
+be added.  By default distributed virtual routing will be disabled.
+
+Developer Impact
+----------------
+
+None identified
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  Erik Colnick (erikcolnick on Launchpad)
+Other contributors:
+  None
+
+Work Items
+----------
+
+ * Create ``neutron-router`` element in tripleo-image-elements and move related
+   contents from ``neutron-network-node`` element.  Remove the
+   ``neutron-dhcp-agent`` dependency from the element-deps of the
+   ``neutron-router`` element.
+
+ * Add the ``neutron-router`` element as a dependency in the
+   ``neutron-network-node`` ``element-deps`` file.  The ``element-deps``
+   file becomes the only content in the ``neutron-network-node`` element.
+
+ * Add the configuration values indicated in
+   https://wiki.openstack.org/wiki/Neutron/DVR/HowTo#Configuration to the
+   ``neutron.conf``, ``l3_agent.ini`` and ``ml2_conf.ini`` files in the
+   ``neutron`` image element.
+
+ * Add the necessary reference variables to the ``nova-compute-config.yaml`` and
+   ``nova-compute-instance.yaml`` tripleo-heat-templates files in order to be
+   able to set the new variables in the config files (from above item).  Add
+   definitions and default values in ``overcloud-source.yaml``.
+
+ * Modify tripleo-incubator ``devtest_overcloud.sh`` script to set the
+   appropriate environment variables which will drive the configuration of
+   neutron on the overcloud to either enable distributed virtual routers or
+   disable distributed virtual routers (with disable as the default).
+
+Dependencies
+============
+
+None
+
+Testing
+=======
+
+Existing TripleO CI will help ensure that as this is implemented, the current
+feature set is not impacted and that the default behavior of disabled
+distributed virtual routers is maintained.
+
+Additional CI tests which test the installation with distributed virtual
+routers should be added as this implementation is completed.
+
+Documentation Impact
+====================
+
+Documentation of the new configuration option will be needed.
+
+References
+==========
+