From 1994d180d0ca8e05b76f2f7b3d6c5e40e5ddd4f4 Mon Sep 17 00:00:00 2001 From: Miguel Lavalle Date: Thu, 27 Jul 2017 14:40:39 -0500 Subject: [PATCH] Add segments service plug-in devref This commit adds a document to devref that explains the implementation of the segments plug-in Change-Id: I80928eac7a6cb051c3d6532d83c9d9ecd328cd18 --- doc/source/contributor/internals/index.rst | 1 + doc/source/contributor/internals/segments.rst | 55 +++++++++++++++++++ 2 files changed, 56 insertions(+) create mode 100644 doc/source/contributor/internals/segments.rst diff --git a/doc/source/contributor/internals/index.rst b/doc/source/contributor/internals/index.rst index edc2f8424c9..8cced837b5e 100644 --- a/doc/source/contributor/internals/index.rst +++ b/doc/source/contributor/internals/index.rst @@ -61,3 +61,4 @@ Neutron Internals retries l3_agent_extensions live_migration + segments diff --git a/doc/source/contributor/internals/segments.rst b/doc/source/contributor/internals/segments.rst new file mode 100644 index 00000000000..5c77a0f6cd4 --- /dev/null +++ b/doc/source/contributor/internals/segments.rst @@ -0,0 +1,55 @@ +.. + Licensed under the Apache License, Version 2.0 (the "License"); you may + not use this file except in compliance with the License. You may obtain + a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + License for the specific language governing permissions and limitations + under the License. + + +Segments extension +================== + +Neutron has an extension that allows CRUD operations on the ``/segments`` +resource in the API, that corresponds to the ``NetworkSegment`` entity in the +DB layer. The extension is implemented as a service plug-in. + +.. note:: The ``segments`` service plug-in is not configured by default. To + configure it, add ``segments`` to the ``service_plugins`` parameter in + ``neutron.conf`` + +Core plug-ins can coordinate with the ``segments`` service plug-in by +subscribing callbacks to events associated to the ``SEGMENT`` resource. +Currently, the segments plug-in notifies subscribers of the following events: + +* ``PRECOMMIT_CREATE`` +* ``AFTER_CREATE`` +* ``BEFORE_DELETE`` +* ``PRECOMMIT_DELETE`` +* ``AFTER_DELETE`` + +As of this writing, ``ML2`` and ``OVN`` register callbacks to receive events +from the ``segments`` service plug-in. The ``ML2`` plug-in defines the +callback ``_handle_segment_change`` to process all the relevant segments +events. + +Segments extension relevant modules +----------------------------------- + +* ``neutron/extensions/segment.py`` defines the extension +* ``neutron/db/models/segment.py`` defines the DB models for segments and for + the segment host mapping, that is used in the implementation of routed + networks. +* ``neutron/db/segments_db.py`` has functions to add, retrieve and delete + segments from the DB. +* ``neutron/services/segments/db.py`` defines a mixin class with the methods + that perform API CRUD operations for the ``segments`` plug-in. It also has a + set of functions to create and maintain the mapping of segments to hosts, + which is necessary in the implementation of routed networks. +* ``neutron/services/segments/plugin.py`` defines the ``segments`` service + plug-in.