Add plugin group names to CONF

Plugins have no way of setting the name of their groups to CONF
so that they are available at discovery time, so setting them
up for them, using the get_opt_list hook.

Since plugins may pass an OptGroup object or a string, handle
both cases. Normalise strings with a '-' to '_'.

Added comments and docstring to document this.

Change-Id: I1afae0d1f9c4a6aec2742aaba4928cdde54b224f

tempest/config.py

@@ -1087,6 +1087,12 @@ class TempestConfigPrivate(object):
         return getattr(_CONF, attr)
 
     def _set_attrs(self):
+        # This methods ensures that config options in Tempest as well as
+        # in Tempest plugins can be accessed via:
+        #     CONF.<normalised_group_name>.<key_name>
+        # where:
+        #     normalised_group_name = group_name.replace('-', '_')
+        # Attributes are set at __init__ time *only* for known option groups
         self.auth = _CONF.auth
         self.compute = _CONF.compute
         self.compute_feature_enabled = _CONF['compute-feature-enabled']
@@ -1108,6 +1114,23 @@ class TempestConfigPrivate(object):
         self.service_available = _CONF.service_available
         self.debug = _CONF.debug
         logging.tempest_set_log_file('tempest.log')
+        # Setting attributes for plugins
+        # NOTE(andreaf) Plugins have no access to the TempestConfigPrivate
+        # instance at discovery time, so they have no way of setting these
+        # aliases themselves.
+        ext_plugins = plugins.TempestTestPluginManager()
+        for group, _ in ext_plugins.get_plugin_options_list():
+            if isinstance(group, cfg.OptGroup):
+                # If we have an OptGroup
+                group_name = group.name
+                group_dest = group.dest
+            else:
+                # If we have a group name as a string
+                group_name = group
+                group_dest = group.replace('-', '_')
+            # NOTE(andreaf) We can set the attribute safely here since in
+            # case of name conflict we would not have reached this point.
+            setattr(self, group_dest, _CONF[group_name])
 
     def __init__(self, parse_conf=True, config_path=None):
         """Initialize a configuration from a conf directory and conf file."""

tempest/test_discover/plugins.py

@@ -46,10 +46,41 @@ class TempestPlugin(object):
         """Add additional configuration options to tempest.
 
         This method will be run for the plugin during the register_opts()
-        function in tempest.config
+        function in tempest.config.
 
         :param ConfigOpts conf: The conf object that can be used to register
             additional options on.
+
+        Example:
+            >>> # Config options are defined in a config.py module
+            >>> service_option = cfg.BoolOpt(
+            >>>     "my_service",
+            >>>     default=True,
+            >>>     help="Whether or not my service is available")
+            >>>
+            >>> # Note: as long as the group is listed in get_opt_lists,
+            >>> # it will be possible to access its optins in the plugin code
+            >>> # via ("-" in the group name are replaces with "_"):
+            >>> #     CONF.my_service.<option_name>
+            >>> my_service_group = cfg.OptGroup(name="my-service",
+            >>>                                 title="My service options")
+            >>>
+            >>> MyServiceGroup = [<list of options>]
+            >>> # (...) More groups and options...
+            >>>
+            >>> # Plugin is implemented in a plugin.py module
+            >>> from my_plugin import config as my_config
+            >>>
+            >>> def register_opts(self, conf):
+            >>>    conf.register_opt(my_config.service_option,
+            >>>                      group='service_available')
+            >>>    conf.register_group(my_config.my_service_group)
+            >>>    conf.register_opts(my_config.MyService +
+            >>>                       my_config.my_service_group)
+            >>>
+            >>>    conf.register_group(my_config.my_service_feature_group)
+            >>>    conf.register_opts(my_config.MyServiceFeaturesGroup,
+            >>>                       my_config.my_service_feature_group)
         """
         return