Make help texts more descriptive in Metaplugin

This patch makes help texts of configuration parameters of
metaplugin.ini more descriptive. Comments in metaplugin.ini
are also improved.

Change-Id: I1fac888ecc223a7199cc9c9aeb603b7493f22171
Closes-Bug: #1283930

etc/neutron/plugins/metaplugin/metaplugin.ini

@@ -1,21 +1,31 @@
+# Config file for Metaplugin
 
 [meta]
-## This is list of flavor:neutron_plugins
-# extension method is used in the order of this list
-# If you use a router service plugin, set 'l3_plugin_list' blank.
-# If 'l3_plugin_list' is not blank, must not specify a router service
-# plugin in 'service_plugins' of neutron.conf.
-plugin_list= 'openvswitch:neutron.plugins.openvswitch.ovs_neutron_plugin.OVSNeutronPluginV2,linuxbridge:neutron.plugins.linuxbridge.lb_neutron_plugin.LinuxBridgePluginV2'
-l3_plugin_list= 'openvswitch:neutron.plugins.openvswitch.ovs_neutron_plugin.OVSNeutronPluginV2,linuxbridge:neutron.plugins.linuxbridge.lb_neutron_plugin.LinuxBridgePluginV2'
+# Comma separated list of flavor:neutron_plugin for plugins to load.
+# Extension method is searched in the list order and the first one is used.
+plugin_list = 'ml2:neutron.plugins.ml2.plugin.Ml2Plugin,nvp:neutron.plugins.vmware.plugin.NsxPluginV2'
 
-# Default value of flavor
-default_flavor = 'openvswitch'
-default_l3_flavor = 'openvswitch'
+# Comma separated list of flavor:neutron_plugin for L3 service plugins
+# to load.
+# This is intended for specifying L2 plugins which support L3 functions.
+# If you use a router service plugin, set this blank.
+l3_plugin_list =
 
-# supported extensions
-supported_extension_aliases = 'providernet'
-# specific method map for each flavor to extensions
+# Default flavor to use, when flavor:network is not specified at network
+# creation.
+default_flavor = 'nvp'
+
+# Default L3 flavor to use, when flavor:router is not specified at router
+# creation.
+# Ignored if 'l3_plugin_list' is blank.
+default_l3_flavor =
+
+# Comma separated list of supported extension aliases.
+supported_extension_aliases = 'provider,binding,agent,dhcp_agent_scheduler'
+
+# Comma separated list of method:flavor to select specific plugin for a method.
+# This has priority over method search order based on 'plugin_list'.
 extension_map = 'get_port_stats:nvp'
 
-# flavor of which plugin handles RPC
-rpc_flavor =
+# Specifies flavor for plugin to handle 'q-plugin' RPC requests.
+rpc_flavor = 'ml2'

neutron/plugins/metaplugin/common/config.py

@@ -19,20 +19,45 @@ from oslo.config import cfg
 
 
 meta_plugin_opts = [
-    cfg.StrOpt('plugin_list', default='',
-               help=_("List of plugins to load")),
-    cfg.StrOpt('l3_plugin_list', default='',
-               help=_("List of L3 plugins to load")),
-    cfg.StrOpt('default_flavor', default='',
-               help=_("Default flavor to use")),
-    cfg.StrOpt('default_l3_flavor', default='',
-               help=_("Default L3 flavor to use")),
-    cfg.StrOpt('supported_extension_aliases', default='',
-               help=_("Supported extension aliases")),
-    cfg.StrOpt('extension_map', default='',
-               help=_("A list of extensions, per plugin, to load.")),
-    cfg.StrOpt('rpc_flavor', default='',
-               help=_("Flavor of which plugin handles RPC")),
+    cfg.StrOpt(
+        'plugin_list',
+        default='',
+        help=_("Comma separated list of flavor:neutron_plugin for "
+               "plugins to load. Extension method is searched in the "
+               "list order and the first one is used.")),
+    cfg.StrOpt(
+        'l3_plugin_list',
+        default='',
+        help=_("Comma separated list of flavor:neutron_plugin for L3 "
+               "service plugins to load. This is intended for specifying "
+               "L2 plugins which support L3 functions. If you use a router "
+               "service plugin, set this blank.")),
+    cfg.StrOpt(
+        'default_flavor',
+        default='',
+        help=_("Default flavor to use, when flavor:network is not "
+               "specified at network creation.")),
+    cfg.StrOpt(
+        'default_l3_flavor',
+        default='',
+        help=_("Default L3 flavor to use, when flavor:router is not "
+               "specified at router creation. Ignored if 'l3_plugin_list' "
+               "is blank.")),
+    cfg.StrOpt(
+        'supported_extension_aliases',
+        default='',
+        help=_("Comma separated list of supported extension aliases.")),
+    cfg.StrOpt(
+        'extension_map',
+        default='',
+        help=_("Comma separated list of method:flavor to select specific "
+               "plugin for a method. This has priority over method search "
+               "order based on 'plugin_list'.")),
+    cfg.StrOpt(
+        'rpc_flavor',
+        default='',
+        help=_("Specifies flavor for plugin to handle 'q-plugin' RPC "
+               "requests.")),
 ]
 
 proxy_plugin_opts = [