public void addUpdateConfigurationsStage(Cluster cluster, String clusterHostInfoJson,
                                             String hostParamsJson, ServiceComponentHostServerActionEvent event,
                                             Map<String, String> commandParameters,
                                             RoleCommandOrder roleCommandOrder, RequestStageContainer requestStageContainer)
      throws AmbariException {
      Stage stage = createServerActionStage(requestStageContainer.getLastStageId(),
        cluster,
        requestStageContainer.getId(),
        "Update Configurations",
        "{}",
        hostParamsJson,
        UpdateKerberosConfigsServerAction.class,
        event,
        commandParameters,
        "Update Service Configurations",
        configuration.getDefaultServerTaskTimeout());

      RoleGraph roleGraph = roleGraphFactory.createNew(roleCommandOrder);
      roleGraph.build(stage);

      requestStageContainer.addStages(roleGraph.getStages());
    }
Send a custom command to the KERBEROS_CLIENT to check if there are missing keytabs on each hosts.
ambari-server/src/main/java/org/apache/ambari/server/controller/KerberosHelperImpl.java