Configure stable service clients via the registry

Push the configuration for stable service clients into the client
registry so that they may be automatically configured in clients.py.
This makes the stable service clients available and pre-configured
to both Tempest and all the plugins, removing the need for the
extra configuration step.

Once all tempest service clients will be stable, several pieces of
code will become redundant, as noted in the code itself.

Change-Id: I6a4845edb95031243bca12a8d03c60cf18528212
diff --git a/tempest/clients.py b/tempest/clients.py
index 406f9d5..e14f6f8 100644
--- a/tempest/clients.py
+++ b/tempest/clients.py
@@ -97,19 +97,16 @@
         This uses `config.service_client_config` for all services to collect
         most configuration items needed to init the clients.
         """
-        # NOTE(andreaf) Configuration items will be passed in future patches
-        # into ClientFactory objects, but for now we update all the
-        # _set_*_client methods to consume them so we can verify that the
-        # configuration collected is correct
+        # NOTE(andreaf) Once all service clients in Tempest are migrated
+        # to tempest.lib, their configuration will be picked up from the
+        # registry, and this method will become redundant.
 
         configuration = {}
 
-        # Setup the parameters for all Tempest services.
+        # Setup the parameters for all Tempest services which are not in lib.
         # NOTE(andreaf) Since client.py is an internal module of Tempest,
         # it doesn't have to consider plugin configuration.
-        all_tempest_modules = (set(clients.tempest_modules()) |
-                               clients._tempest_internal_modules())
-        for service in all_tempest_modules:
+        for service in clients._tempest_internal_modules():
             try:
                 # NOTE(andreaf) Use the unversioned service name to fetch
                 # the configuration since configuration is not versioned.
diff --git a/tempest/config.py b/tempest/config.py
index 6bae021..d67de33 100644
--- a/tempest/config.py
+++ b/tempest/config.py
@@ -26,6 +26,7 @@
 import testtools
 
 from tempest.lib import exceptions
+from tempest.lib.services import clients
 from tempest.test_discover import plugins
 
 
@@ -1287,6 +1288,15 @@
             lockutils.set_defaults(lock_dir)
             self._config = TempestConfigPrivate(config_path=self._path)
 
+            # Pushing tempest internal service client configuration to the
+            # service clients register. Doing this in the config module ensures
+            # that the configuration is available by the time we register the
+            # service clients.
+            # NOTE(andreaf) This has to be done at the time the first
+            # attribute is accessed, to ensure all plugins have been already
+            # loaded, options registered, and _config is set.
+            _register_tempest_service_clients()
+
         return getattr(self._config, attr)
 
     def set_config_path(self, path):
@@ -1446,3 +1456,29 @@
     # Set service
     _parameters['service'] = getattr(options, 'catalog_type')
     return _parameters
+
+
+def _register_tempest_service_clients():
+    # Register tempest own service clients using the same mechanism used
+    # for external plugins.
+    # The configuration data is pushed to the registry so that automatic
+    # configuration of tempest own service clients is possible both for
+    # tempest as well as for the plugins.
+    service_clients = clients.tempest_modules()
+    registry = clients.ClientsRegistry()
+    all_clients = []
+    for service_client in service_clients:
+        module = service_clients[service_client]
+        configs = service_client.split('.')[0]
+        service_client_data = dict(
+            name=service_client.replace('.', '_'),
+            service_version=service_client,
+            module_path=module.__name__,
+            client_names=module.__all__,
+            **service_client_config(configs)
+        )
+        all_clients.append(service_client_data)
+    # NOTE(andreaf) Internal service clients do not actually belong
+    # to a plugin, so using '__tempest__' to indicate a virtual plugin
+    # which holds internal service clients.
+    registry.register_service_client('__tempest__', all_clients)
diff --git a/tempest/lib/services/clients.py b/tempest/lib/services/clients.py
index e782321..adf666b 100644
--- a/tempest/lib/services/clients.py
+++ b/tempest/lib/services/clients.py
@@ -18,7 +18,6 @@
 import importlib
 import inspect
 import logging
-import six
 
 from tempest.lib import auth
 from tempest.lib.common.utils import misc
@@ -90,11 +89,14 @@
                                                 plug_service_versions))
                 raise exceptions.PluginRegistrationException(
                     name=plugin_name, detailed_error=detailed_error)
-            if not plug_service_versions.isdisjoint(_tempest_modules):
+            # NOTE(andreaf) Once all tempest clients are stable, the following
+            # if will have to be removed.
+            if not plug_service_versions.isdisjoint(
+                    _tempest_internal_modules()):
                 detailed_error = (
                     'Plugin %s is trying to register a service %s already '
                     'claimed by a Tempest one' % (plugin_name,
-                                                  _tempest_modules &
+                                                  _tempest_internal_modules() &
                                                   plug_service_versions))
                 raise exceptions.PluginRegistrationException(
                     name=plugin_name, detailed_error=detailed_error)
@@ -351,15 +353,7 @@
             raise exceptions.UnknownServiceClient(
                 services=list(client_parameters.keys()))
 
-        # Register service clients owned by tempest
-        for service, module in six.iteritems(tempest_modules()):
-            attribute = service.replace('.', '_')
-            configs = service.split('.')[0]
-            self.register_service_client_module(
-                attribute, service, module.__name__,
-                module.__all__, **self.parameters[configs])
-
-        # Register service clients from plugins
+        # Register service clients from the registry (__tempest__ and plugins)
         clients_registry = ClientsRegistry()
         plugin_service_clients = clients_registry.get_service_clients()
         for plugin in plugin_service_clients:
@@ -432,6 +426,8 @@
 
     @property
     def registered_services(self):
+        # NOTE(andreaf) Once all tempest modules are stable this needs to
+        # be updated to remove _tempest_internal_modules
         return self._registered_services | _tempest_internal_modules()
 
     def _setup_parameters(self, parameters):