Introduces example of running a method on a resource

Example provides support for invoking arbirary methods on a resource object.

Change-Id: Ib07a974f188c76690ab7cd43cbfda503a5e81b9a

examples/action.py

@@ -0,0 +1,75 @@
+# 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.
+
+"""
+Example Action Command
+
+Invoke an action method on a resource.
+
+A session will be provided to the action if needed. The action itself
+must be identified by the 'action' key. Arguments to the action may be
+provided through an 'action_args' dictionary.
+
+For examples:
+    python -m examples.action openstack/telemetry/v2/alarm.py \
+           --data '{"alarm_id": "33109eea-24dd-45ff-93f7-82292d1dd38c",
+                    "action": "change_state",
+                    "action_args": {"next_state": "insufficient data"}'
+
+    python -m examples.action openstack/compute/v2/server.py \
+           --data '{"id": "a1369557-748f-429c-bd3e-fc385aacaec7",
+                    "action": "reboot",
+                    "action_args": {"reboot_type": "SOFT"}}'
+"""
+
+import inspect
+import sys
+
+from examples import common
+from examples import session
+
+
+def filter_args(method, params):
+    expected_args = inspect.getargspec(method).args
+    accepted_args = ([a for a in expected_args if a != 'self'])
+    filtered_args = {desired: params[desired] for desired in accepted_args}
+    return filtered_args
+
+
+def invoke_method(target, method_name, params):
+    action = getattr(target, method_name)
+    filtered_args = filter_args(action, params)
+    reply = action(**filtered_args)
+    return reply
+
+
+def run_action(options):
+    sess = session.make_session(options)
+    cls = common.find_resource_cls(options)
+    data = common.get_data_option(options)
+
+    action = data.pop('action')
+    if 'action_args' in data:
+        args = data.pop('action_args')
+    else:
+        args = {}
+    args.update(session=sess)
+
+    obj = cls.new(**data)
+    reply = invoke_method(obj, action, args)
+    print(str(reply))
+    return
+
+
+if __name__ == "__main__":
+    opts = common.setup()
+    sys.exit(common.main(opts, run_action))