def scale_rc(self, manifest_filename, namespace="<STR_LIT:default>", num_replicas=<NUM_LIT:0>):
rc_manifest, rc_manifest_json = util.load_yaml(filename=manifest_filename)<EOL>logging.debug("<STR_LIT:%s>" %(rc_manifest_json))<EOL>rc_path = "<STR_LIT>".join(["<STR_LIT>", namespace, "<STR_LIT>", rc_manifest["<STR_LIT>"]["<STR_LIT:name>"]])<EOL>rc_manifest["<STR_LIT>"]["<STR_LIT>"] = num_replicas<EOL>res = self.execute_operation(method="<STR_LIT>", ops_path=rc_path, payload=util.serialize_tojson(rc_manifest))<EOL>try:<EOL><INDENT>rc_url = res.json()["<STR_LIT>"]["<STR_LIT>"]<EOL><DEDENT>except KeyError:<EOL><INDENT>raise ResourceCRUDException("<STR_LIT>".join(["<STR_LIT>", rc_manifest["<STR_LIT>"]["<STR_LIT:name>"]]))<EOL><DEDENT>logging.info("<STR_LIT>" %(rc_manifest["<STR_LIT>"]["<STR_LIT:name>"], rc_url, num_replicas))<EOL>return (res, rc_url)<EOL>
Changes the replicas of an RC based on a manifest.
Note that it defaults to 0, meaning to effectively disable this RC.

:Parameters:
   - `manifest_filename`: The manifest file containing the ReplicationController definition, for example: `manifest/nginx-webserver-rc.yaml`
   - `namespace`: In which namespace the RC is, defaulting to `default`
   - `num_replicas`: How many copies of the pods that match the selector are supposed to run