Clean up configuration option management

Move the option definitions into the opts module with the other
functions related to options.

Add set_defaults() to override the default settings for options and make
it part of the public API of the library by including it in the
documentation.

Add opts._register() so the options can be registered consistently from
multiple places.

Change-Id: Ib74beac58a07bf5ee0f92c2b7eda8281ef7d7c33

doc/source/api.rst

@@ -2,5 +2,14 @@
  API
 =====
 
+oslo_policy.policy
+==================
+
 .. automodule:: oslo_policy.policy
    :members:
+
+oslo_policy.opts
+================
+
+.. automodule:: oslo_policy.opts
+   :members:

oslo_policy/opts.py

@@ -11,12 +11,40 @@
 #    under the License.
 
 __all__ = [
-    'list_opts'
+    'list_opts',
+    'set_defaults',
 ]
 
 import copy
 
-from oslo_policy import policy
+from oslo_config import cfg
+
+from oslo_policy._i18n import _
+
+
+_option_group = 'oslo_policy'
+
+_options = [
+    cfg.StrOpt('policy_file',
+               default='policy.json',
+               help=_('The JSON file that defines policies.'),
+               deprecated_group='DEFAULT'),
+    cfg.StrOpt('policy_default_rule',
+               default='default',
+               help=_('Default rule. Enforced when a requested rule is not '
+                      'found.'),
+               deprecated_group='DEFAULT'),
+    cfg.MultiStrOpt('policy_dirs',
+                    default=['policy.d'],
+                    help=_('Directories where policy configuration files are '
+                           'stored. They can be relative to any directory '
+                           'in the search path defined by the config_dir '
+                           'option, or absolute paths. The file defined by '
+                           'policy_file must exist for these directories to '
+                           'be searched.  Missing or empty directories are'
+                           'ignored.'),
+                    deprecated_group='DEFAULT'),
+]
 
 
 def list_opts():
@@ -36,4 +64,31 @@ def list_opts():
     :returns: a list of (group_name, opts) tuples
     """
 
-    return [('oslo_policy', copy.deepcopy(policy._opts))]
+    return [(_option_group, copy.deepcopy(_options))]
+
+
+def _register(conf):
+    """Register the policy options.
+
+    We do this in a few places, so use a function to ensure it is done
+    consistently.
+    """
+    conf.register_opts(_options, group=_option_group)
+
+
+def set_defaults(conf, policy_file=None):
+    """Set defaults for configuration variables.
+
+    Overrides default options values.
+
+    :param conf: Configuration object, managed by the caller.
+    :type conf: oslo.config.cfg.ConfigOpts
+
+    :param policy_file: The base filename for the JSON file that
+                        defines policies.
+    :type policy_file: unicode
+    """
+    _register(conf)
+
+    if policy_file is not None:
+        conf.set_default('policy_file', policy_file, group=_option_group)

oslo_policy/policy.py

@@ -213,29 +213,7 @@ from oslo_policy import _checks
 from oslo_policy._i18n import _
 from oslo_policy import _parser
 from oslo_policy.openstack.common import fileutils
-
-
-_opts = [
-    cfg.StrOpt('policy_file',
-               default='policy.json',
-               help=_('The JSON file that defines policies.'),
-               deprecated_group='DEFAULT'),
-    cfg.StrOpt('policy_default_rule',
-               default='default',
-               help=_('Default rule. Enforced when a requested rule is not '
-                      'found.'),
-               deprecated_group='DEFAULT'),
-    cfg.MultiStrOpt('policy_dirs',
-                    default=['policy.d'],
-                    help=_('Directories where policy configuration files are '
-                           'stored. They can be relative to any directory '
-                           'in the search path defined by the config_dir '
-                           'option, or absolute paths. The file defined by '
-                           'policy_file must exist for these directories to '
-                           'be searched.  Missing or empty directories are'
-                           'ignored.'),
-                    deprecated_group='DEFAULT'),
-]
+from oslo_policy import opts
 
 
 LOG = logging.getLogger(__name__)
@@ -327,7 +305,7 @@ class Enforcer(object):
     def __init__(self, conf, policy_file=None, rules=None,
                  default_rule=None, use_conf=True, overwrite=True):
         self.conf = conf
-        self.conf.register_opts(_opts, group='oslo_policy')
+        opts._register(conf)
 
         self.default_rule = (default_rule or
                              self.conf.oslo_policy.policy_default_rule)

oslo_policy/tests/test_opts.py

@@ -0,0 +1,31 @@
+#    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 fixture as config
+from oslotest import base as test_base
+
+from oslo_policy import opts
+
+
+class OptsTestCase(test_base.BaseTestCase):
+
+    def setUp(self):
+        super(OptsTestCase, self).setUp()
+        self.conf = self.useFixture(config.Config()).conf
+
+    def test_set_defaults_policy_file(self):
+        opts._register(self.conf)
+        self.assertNotEqual('new-value.json',
+                            self.conf.oslo_policy.policy_file)
+        opts.set_defaults(self.conf, policy_file='new-value.json')
+        self.assertEqual('new-value.json',
+                         self.conf.oslo_policy.policy_file)