Consolidate policy deprecation warnings

Suppress noisy deprecation warnings in favor of a single blanket
warning. Oslopolicy-policy-generator will still emit the same
deprecation warnings, and oslopolicy-policy-upgrade can be used to
migrate existing custom policies to the upgraded version.

This change requires no modification to oslo.policy and so no new
release or requirements bump will be needed.

Change-Id: I3c27c61cee3527b39f6a167b11198ab066614a1d
Closes-bug: #1836568

keystone/common/rbac_enforcer/enforcer.py

@@ -53,6 +53,40 @@ class RBACEnforcer(object):
         # BORG pattern.
         self.__dict__ = self.__shared_state__
 
+    def _check_deprecated_rule(self, action):
+        def _name_is_changing(rule):
+            deprecated_rule = rule.deprecated_rule
+            return (deprecated_rule and
+                    deprecated_rule.name != rule.name and
+                    deprecated_rule.name in self._enforcer.file_rules)
+
+        def _check_str_is_changing(rule):
+            deprecated_rule = rule.deprecated_rule
+            return (deprecated_rule and
+                    deprecated_rule.check_str != rule.check_str and
+                    rule.name not in self._enforcer.file_rules)
+
+        def _is_deprecated_for_removal(rule):
+            return (rule.deprecated_for_removal and
+                    rule.name in self._enforcer.file_rules)
+
+        def _emit_warning():
+            if not self._enforcer._warning_emitted:
+                LOG.warning("Deprecated policy rules found. Use "
+                            "oslopolicy-policy-generator and "
+                            "oslopolicy-policy-upgrade to detect and resolve "
+                            "deprecated policies in your configuration.")
+                self._enforcer._warning_emitted = True
+
+        registered_rule = self._enforcer.registered_rules.get(action)
+
+        if not registered_rule:
+            return
+        if (_name_is_changing(registered_rule) or
+                _check_str_is_changing(registered_rule) or
+                _is_deprecated_for_removal(registered_rule)):
+            _emit_warning()
+
     def _enforce(self, credentials, action, target, do_raise=True):
         """Verify that the action is valid on the target in this context.
 
@@ -80,8 +114,10 @@ class RBACEnforcer(object):
                          do_raise=do_raise)
 
         try:
-            return self._enforcer.enforce(
+            result = self._enforcer.enforce(
                 rule=action, target=target, creds=credentials, **extra)
+            self._check_deprecated_rule(action)
+            return result
         except common_policy.InvalidScope:
             raise exception.ForbiddenAction(action=action)
 
@@ -94,9 +130,22 @@ class RBACEnforcer(object):
         # The raw oslo-policy enforcer object
         if self.__ENFORCER is None:
             self.__ENFORCER = common_policy.Enforcer(CONF)
+            # NOTE(cmurphy) when running in the keystone server, suppress
+            # deprecation warnings for individual policy rules. Instead, we log
+            # a single notification at enforcement time indicating the
+            # oslo.policy tools the operator can use to detect and resolve
+            # deprecated policies. If there is no request context here, that
+            # means external tooling such as the oslo.policy tools are running
+            # this code, in which case we do want the full deprecation warnings
+            # emitted for individual polcy rules.
+            if flask.has_request_context():
+                self.__ENFORCER.suppress_deprecation_warnings = True
+            # NOTE(cmurphy) Tests may explicitly disable these warnings to
+            # prevent an explosion of test logs
             if self.suppress_deprecation_warnings:
                 self.__ENFORCER.suppress_deprecation_warnings = True
             self.register_rules(self.__ENFORCER)
+            self.__ENFORCER._warning_emitted = False
         return self.__ENFORCER
 
     @staticmethod

releasenotes/notes/bug-1836568-66d853a1f22c5530.yaml

@@ -0,0 +1,10 @@
+---
+fixes:
+  - |
+    [`bug 1836568 <https://bugs.launchpad.net/keystone/+bug/1836568>`_
+    Addresses a side effect of the large series of policy migrations in which
+    the volume of deprecation warnings that were emitted had become too massive
+    to be helpful. Instead of emitting warnings for individual policy rules,
+    the keystone server now emits a single warning indicating problematic rules
+    were found. Operators can use oslopolicy-policy-generator and
+    oslopolicy-policy-upgrade to find and resolve deprecated policies.