Add entry_point for oslo policy scripts

With the setup.cfg entry it can  be called directly from
oslo.policy.

$oslopolicy-policy-generator --namespace heat

This will get the effective policy that’s being executed.

Change-Id: Iad2e71819f4847f47dd17d3cd4afa78e6b3f52a7
Story: #2005055
Task: 29573

heat/common/policy.py

@@ -51,6 +51,8 @@ class Enforcer(object):
 
         # register rules
         self.enforcer.register_defaults(policies.list_rules())
+        self.file_rules = self.enforcer.file_rules
+        self.registered_rules = self.enforcer.registered_rules
 
     def set_rules(self, rules, overwrite=True):
         """Create a new Rules object based on the provided dict of rules."""
@@ -118,6 +120,13 @@ class Enforcer(object):
                            is_registered_policy=True)
 
 
+def get_policy_enforcer():
+    # This method is used by oslopolicy CLI scripts to generate policy
+    # files from overrides on disk and defaults in code.
+    CONF([], project='heat')
+    return get_enforcer()
+
+
 def get_enforcer():
     global ENFORCER
     if ENFORCER is None:

setup.cfg

@@ -60,6 +60,9 @@ oslo.config.opts =
 oslo.config.opts.defaults =
     heat.common.config = heat.common.config:set_config_defaults
 
+oslo.policy.enforcer =
+    heat = heat.common.policy:get_policy_enforcer
+
 oslo.policy.policies =
     heat = heat.policies:list_rules