Add example group for the URI driver

Ensure the sample generator emits an example group with
instructions on how to define extra URI sources.

Change-Id: Ica556771d8dd37cb02d9ca69c04e888d187041ee
Blueprint: oslo-config-drivers
Signed-off-by: Moises Guimaraes de Medeiros <moguimar@redhat.com>

5 files changed, 86 insertions, 15 deletions

diff --git a/oslo_config/_list_opts.py b/oslo_config/_list_opts.py
index 701ff18..2a318c4 100644
--- a/oslo_config/_list_opts.py
+++ b/oslo_config/_list_opts.py
@@ -12,6 +12,8 @@
 
 from oslo_config import cfg
 
+import stevedore
+
 
 def list_opts():
     default_config_files = [
@@ -26,8 +28,17 @@ def list_opts():
         '/etc/project/project.conf.d/',
         '/etc/project.conf.d/',
     ]
-    options = cfg.ConfigOpts._list_options_for_discovery(
+    options = [(None, cfg.ConfigOpts._list_options_for_discovery(
         default_config_files,
         default_config_dirs,
-    )
-    return [(None, options)]
+    ))]
+
+    ext_mgr = stevedore.ExtensionManager(
+        "oslo.config.driver",
+        invoke_on_load=True)
+
+    for driver in ext_mgr.names():
+        options.append(('sample_%s_source' % driver,
+                       ext_mgr[driver].obj.list_options_for_discovery()))
+
+    return options
diff --git a/oslo_config/cfg.py b/oslo_config/cfg.py
index 0f89e49..ea33b26 100644
--- a/oslo_config/cfg.py
+++ b/oslo_config/cfg.py
@@ -503,7 +503,7 @@ from oslo_config import iniparser
 from oslo_config import sources
 from oslo_config import types
 
-from stevedore.extension import ExtensionManager
+import stevedore
 
 LOG = logging.getLogger(__name__)
 
@@ -2544,7 +2544,7 @@ class ConfigOpts(collections.Mapping):
 
     def _open_source_from_opt_group(self, group_name):
         if not self._ext_mgr:
-            self._ext_mgr = ExtensionManager(
+            self._ext_mgr = stevedore.ExtensionManager(
                 "oslo.config.driver",
                 invoke_on_load=True)
 
diff --git a/oslo_config/sources/__init__.py b/oslo_config/sources/__init__.py
index e338d26..47565fa 100644
--- a/oslo_config/sources/__init__.py
+++ b/oslo_config/sources/__init__.py
@@ -46,6 +46,19 @@ class ConfigurationSourceDriver(object):
         :returns: an instance of a subclass of ConfigurationSource
         """
 
+    @abc.abstractmethod
+    def list_options_for_discovery(self):
+        """Return a list of options used by the driver to create the source.
+
+        Drivers should advertise all supported options in this method for the
+        purpose of sample generation by oslo-config-generator.
+
+        For an example on how to implement this method you can check the URI
+        driver at oslo_config.sources._uri.URIConfigurationSourceDriver.
+
+        :returns: a list of supported options of a ConfigurationSource.
+        """
+
 
 @six.add_metaclass(abc.ABCMeta)
 class ConfigurationSource(object):
diff --git a/oslo_config/sources/_uri.py b/oslo_config/sources/_uri.py
index 8e19cf0..f868824 100644
--- a/oslo_config/sources/_uri.py
+++ b/oslo_config/sources/_uri.py
@@ -35,17 +35,49 @@ class URIConfigurationSourceDriver(sources.ConfigurationSourceDriver):
                     specified but does not includes the private key.
     """
 
-    def open_source_from_opt_group(self, conf, group_name):
-        group = cfg.OptGroup(group_name)
-
-        conf.register_opt(cfg.URIOpt("uri",
-                                     schemes=["http", "https"],
-                                     required=True),
-                          group)
+    _uri_driver_opts = [
+        cfg.URIOpt(
+            'uri',
+            schemes=['http', 'https'],
+            required=True,
+            help=('Required option with the URI of the '
+                  'extra configuration file\'s location.'),
+        ),
+        cfg.StrOpt(
+            'ca_path',
+            help=('The path to a CA_BUNDLE file or directory '
+                  'with certificates of trusted CAs.'),
+        ),
+        cfg.StrOpt(
+            'client_cert',
+            help=('Client side certificate, as a single file path '
+                  'containing either the certificate only or the '
+                  'private key and the certificate.'),
+        ),
+        cfg.StrOpt(
+            'client_key',
+            help=('Client side private key, in case client_cert is '
+                  'specified but does not includes the private key.'),
+        ),
+    ]
+
+    def list_options_for_discovery(self):
+        # NOTE(moguimar): This option is only used to provide a better
+        #                 description of the driver option registered
+        #                 by ConfigOpts._open_source_from_opt_group().
+        driver_opt = cfg.StrOpt(
+            'driver',
+            default='remote_file',
+            help=('Required option and value for this group to be '
+                  'parsed as an extra source by the URI driver. '
+                  'This group\'s name must be set as one of the '
+                  'config_source\'s values in the [DEFAULT] group.'),
+        )
+
+        return [driver_opt] + self._uri_driver_opts
 
-        conf.register_opt(cfg.StrOpt("ca_path"), group)
-        conf.register_opt(cfg.StrOpt("client_cert"), group)
-        conf.register_opt(cfg.StrOpt("client_key"), group)
+    def open_source_from_opt_group(self, conf, group_name):
+        conf.register_opts(self._uri_driver_opts, group_name)
 
         return URIConfigurationSource(
             conf[group_name].uri,
diff --git a/oslo_config/tests/test_sources.py b/oslo_config/tests/test_sources.py
index 69ba645..0ca389c 100644
--- a/oslo_config/tests/test_sources.py
+++ b/oslo_config/tests/test_sources.py
@@ -12,6 +12,7 @@
 
 from requests import HTTPError
 
+from oslo_config import _list_opts
 from oslo_config import cfg
 from oslo_config import fixture
 from oslo_config import sources
@@ -279,3 +280,17 @@ class URISourceTestCase(base.BaseTestCase):
         # the option name and option value will match correctly
         for option in _extra_configs[uri]["data"]["DEFAULT"]:
             self.assertEqual(option, self.conf[option])
+
+    def test_list_opts(self):
+        expected_group = None
+        for group in _list_opts.list_opts():
+            if group[0] == "sample_remote_file_source":
+                expected_group = group
+                break
+
+        self.assertIsNotNone(expected_group)
+
+        self.assertEqual(
+            expected_group[1],
+            _uri.URIConfigurationSourceDriver().list_options_for_discovery()
+        )