Add policy sample generation

This adds the entry point and config file necessary for using the
oslo.policy sample generation script. It also adds a tox target to
simplify the usage of it.

Change-Id: I7feb522b2ea5f56e48982169c7ebbb2ec2ef2cb3
Partially-Implements: bp policy-in-code

etc/keystone-policy-generator.conf

@@ -0,0 +1,3 @@
+[DEFAULT]
+output_file = etc/keystone.policy.yaml.sample
+namespace = keystone

setup.cfg

@@ -184,6 +184,11 @@ oslo.config.opts =
 oslo.config.opts.defaults =
     keystone = keystone.conf:set_external_opts_defaults
 
+oslo.policy.policies =
+    # With the move of default policy in code list_rules returns a list of
+    # the default defined polices.
+    keystone = keystone.common.policies:list_rules
+
 paste.filter_factory =
     healthcheck = oslo_middleware:Healthcheck.factory
     cors = oslo_middleware:CORS.factory

tox.ini

@@ -123,6 +123,9 @@ commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasen
 [testenv:genconfig]
 commands = oslo-config-generator --config-file=config-generator/keystone.conf
 
+[testenv:genpolicy]
+commands = oslopolicy-sample-generator --config-file etc/keystone-policy-generator.conf
+
 [hacking]
 import_exceptions =
   keystone.i18n