Here's how to find which host components have stale configs (need to be restarted or have config refreshed).
Request:
curl -uadmin:admin http://localhost:8080/api/v1/clusters/c1/host_components?HostRoles/stale_configs=true&fields=HostRoles/service_name,HostRoles/state,HostRoles/host_name,HostRoles/stale_configs,&minimal_response=true
Response:
{ "items" : [ { "HostRoles" : { "component_name" : "DATANODE", "host_name" : "c6401.ambari.apache.org", "service_name" : "HDFS", "stale_configs" : true, "state" : "STARTED" }, "host" : { "href" : "http://127.0.0.1:8080/api/v1/clusters/c1/hosts/c6401.ambari.apache.org" } }, { "HostRoles" : { "component_name" : "HDFS_CLIENT", "host_name" : "c6401.ambari.apache.org", "service_name" : "HDFS", "stale_configs" : true, "state" : "INSTALLED" }, "host" : { "href" : "http://127.0.0.1:8080/api/v1/clusters/c1/hosts/c6401.ambari.apache.org" } }, { "HostRoles" : { "component_name" : "NAMENODE", "host_name" : "c6401.ambari.apache.org", "service_name" : "HDFS", "stale_configs" : true, "state" : "STARTED" }, "host" : { "href" : "http://127.0.0.1:8080/api/v1/clusters/c1/hosts/c6401.ambari.apache.org" } }, { "HostRoles" : { "component_name" : "SECONDARY_NAMENODE", "host_name" : "c6401.ambari.apache.org", "service_name" : "HDFS", "stale_configs" : true, "state" : "INSTALLED" }, "host" : { "href" : "http://127.0.0.1:8080/api/v1/clusters/c1/hosts/c6401.ambari.apache.org" } } ] }