register the built-in options for the config generator to find

Change-Id: Ic570fece888a1a115bec976b368d0efb9b1b4686

oslo_config/_list_opts.py

@@ -0,0 +1,25 @@
+#    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.
+
+from oslo_config import cfg
+
+
+def list_opts():
+    default_config_files = [
+        '~/.project/project.conf',
+        '~/project.conf',
+        '/etc/project/project.conf',
+        '/etc/project.conf',
+    ]
+    return [
+        (None, cfg.ConfigOpts._make_config_options(default_config_files)),
+    ]

oslo_config/cfg.py

@@ -1948,17 +1948,16 @@ class ConfigOpts(collections.Mapping):
 
         return prog, default_config_files
 
-    def _setup(self, project, prog, version, usage, default_config_files):
-        """Initialize a ConfigOpts object for option parsing."""
-
-        self._config_opts = [
+    @staticmethod
+    def _make_config_options(default_config_files):
+        return [
             _ConfigFileOpt('config-file',
                            default=default_config_files,
                            metavar='PATH',
                            help=('Path to a config file to use. Multiple '
                                  'config files can be specified, with values '
-                                 'in later files taking precedence. The '
-                                 'default files used are: %(default)s.')),
+                                 'in later files taking precedence. Defaults '
+                                 'to %(default)s.')),
             _ConfigDirOpt('config-dir',
                           metavar='DIR',
                           help='Path to a config directory to pull *.conf '
@@ -1970,6 +1969,11 @@ class ConfigOpts(collections.Mapping):
                                'over-ridden options in the directory take '
                                'precedence.'),
         ]
+
+    def _setup(self, project, prog, version, usage, default_config_files):
+        """Initialize a ConfigOpts object for option parsing."""
+
+        self._config_opts = self._make_config_options(default_config_files)
         self.register_cli_opts(self._config_opts)
 
         self.project = project

setup.cfg

@@ -30,6 +30,8 @@ setup-hooks =
 [entry_points]
 console_scripts =
     oslo-config-generator = oslo_config.generator:main
+oslo.config.opts =
+    oslo.config = oslo_config._list_opts:list_opts
 
 [build_sphinx]
 source-dir = doc/source