private List<RequestResourceFilter> createRequestResourceFilters(List<String> hostsToInclude) {
      List<RequestResourceFilter> requestResourceFilters = new ArrayList<>();
      RequestResourceFilter reqResFilter = new RequestResourceFilter(Service.Type.KERBEROS.name(), Role.KERBEROS_CLIENT.name(), hostsToInclude);
      requestResourceFilters.add(reqResFilter);
      return requestResourceFilters;
    }
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