Add support for testing custom RBAC requirements

Add support of running Patrole against a custom requirements YAML that
defines RBAC requirements. The YAML file lists all the APIs and the roles
that should have access to the APIs. The purpose of running Patrole against
a requirements YAML is to verify that the RBAC policy is in accordance to
deployment specific requirements. Running Patrole against a requirements
YAML is completely optional and can be enabled through the rbac section of
the tempest.conf.

Change-Id: I8ba89ab5e134b15e97ac20a7aacbfd70896e192f
Implements: blueprint support-custom-yaml
Co-Authored-By: Sangeet Gupta <sg774j@att.com>
Co-Authored-By: David Purcell <d.purcell222@gmail.com>
diff --git a/patrole_tempest_plugin/requirements_authority.py b/patrole_tempest_plugin/requirements_authority.py
new file mode 100644
index 0000000..2db12db
--- /dev/null
+++ b/patrole_tempest_plugin/requirements_authority.py
@@ -0,0 +1,72 @@
+# Copyright 2017 AT&T Corporation.
+# All Rights Reserved.
+#
+#    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.
+import yaml
+
+from oslo_log import log as logging
+
+from tempest.lib import exceptions
+
+from patrole_tempest_plugin.rbac_utils import RbacAuthority
+
+LOG = logging.getLogger(__name__)
+
+
+class RequirementsParser(object):
+    _inner = None
+
+    class Inner(object):
+        _rbac_map = None
+
+        def __init__(self, filepath):
+            with open(filepath) as f:
+                RequirementsParser.Inner._rbac_map = \
+                    list(yaml.safe_load_all(f))
+
+    def __init__(self, filepath):
+        if RequirementsParser._inner is None:
+            RequirementsParser._inner = RequirementsParser.Inner(filepath)
+
+    @staticmethod
+    def parse(component):
+        try:
+            for section in RequirementsParser.Inner._rbac_map:
+                if component in section:
+                    return section[component]
+        except yaml.parser.ParserError:
+            LOG.error("Error while parsing the requirements YAML file. Did "
+                      "you pass a valid component name from the test case?")
+        return None
+
+
+class RequirementsAuthority(RbacAuthority):
+    def __init__(self, filepath=None, component=None):
+        if filepath is not None and component is not None:
+            self.roles_dict = RequirementsParser(filepath).parse(component)
+        else:
+            self.roles_dict = None
+
+    def allowed(self, rule_name, role):
+        if self.roles_dict is None:
+            raise exceptions.InvalidConfiguration(
+                "Roles dictionary parsed from requirements YAML file is "
+                "empty. Ensure the requirements YAML file is correctly "
+                "formatted.")
+        try:
+            _api = self.roles_dict[rule_name]
+            return role in _api
+        except KeyError:
+            raise KeyError("'%s' API is not defined in the requirements YAML "
+                           "file" % rule_name)
+        return False