devref doc config option separation

Document separation of configuration options between services and agents.

Configurations used in devstack and deployment documentation should also be
updated since they are referenced as examples.

Partial-Bug: #1557119
Change-Id: Ia4b2a542cded6cc56c1b3eaa9e9b9e0abff31707
This commit is contained in:
Dustin Lundquist 2016-02-02 11:27:56 -08:00
parent 53c03f5ed3
commit 1257af45ea
1 changed files with 24 additions and 0 deletions

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@ -83,3 +83,27 @@ Connecting to the Database
Only the neutron-server connects to the neutron database. Agents may never
connect directly to the database, as this would break the ability to do rolling
upgrades.
Configuration Options
---------------------
In addition to database access, configuration options are segregated between
neutron-server and agents. Both services and agents may load the main
```neutron.conf``` since this file should contain the oslo.messaging
configuration for internal Neutron RPCs and may contain host specific
configuration such as file paths. In addition ```neutron.conf``` contains the
database, Keystone, and Nova credentials and endpoints strictly for
neutron-server to use.
In addition neutron-server may load a plugin specific configuration file, yet
the agents should not. As the plugin configuration is primarily site wide
options and the plugin provides the persistence layer for Neutron, agents
should be instructed to act upon these values via RPC.
Each individual agent may have its own configuration file. This file should be
loaded after the main ```neutron.conf``` file, so the agent configuration takes
precedence. The agent specific configuration may contain configurations which
vary between hosts in a Neutron deployment such as the external_network_bridge
for a L3 agent. If any agent requires access to additional external services
beyond the Neutron RPC, those endpoints should be defined in the agent specific
configuration file (e.g. nova metadata for metadata agent).