public void validateAction(ExecuteActionRequest actionRequest) throws AmbariException {
    if (actionRequest.getActionName() == null || actionRequest.getActionName().isEmpty()) {
      throw new AmbariException("Action name must be specified");
    }

    ActionDefinition actionDef = ambariMetaInfo.getActionDefinition(actionRequest.getActionName());
    if (actionDef == null) {
      throw new AmbariException("Action " + actionRequest.getActionName() + " does not exist");
    }

    if (actionDef.getInputs() != null) {
      String[] inputs = actionDef.getInputs().split(",");
      for (String input : inputs) {
        String inputName = input.trim();
        if (!inputName.isEmpty()) {
          boolean mandatory = true;
          if (inputName.startsWith("[") && inputName.endsWith("]")) {
            mandatory = false;
          }
          if (mandatory && !actionRequest.getParameters().containsKey(inputName)) {
            throw new AmbariException("Action " + actionRequest.getActionName() + " requires input '" +
              input.trim() + "' that is not provided.");
          }
        }
      }
    }

    List<RequestResourceFilter> resourceFilters = actionRequest.getResourceFilters();
    RequestResourceFilter resourceFilter = null;
    if (resourceFilters != null && !resourceFilters.isEmpty()) {
      if (resourceFilters.size() > 1) {
        throw new AmbariException("Custom action definition only allows one " +
          "resource filter to be specified.");
      } else {
        resourceFilter = resourceFilters.get(0);
      }
    }

    String targetService = "";
    String targetComponent = "";

    if (null != actionRequest.getClusterName()) {
      Cluster cluster = clusters.getCluster(actionRequest.getClusterName());

      if (cluster == null) {
        throw new AmbariException("Unable to find cluster. clusterName = " +
          actionRequest.getClusterName());
      }

      String expectedService = actionDef.getTargetService() == null ? "" : actionDef.getTargetService();

      String actualService = resourceFilter == null || resourceFilter.getServiceName() == null ? "" : resourceFilter.getServiceName();
      if (!expectedService.isEmpty() && !actualService.isEmpty() && !expectedService.equals(actualService)) {
        throw new AmbariException("Action " + actionRequest.getActionName() + " targets service " + actualService +
          " that does not match with expected " + expectedService);
      }

      targetService = expectedService;
      if (StringUtils.isBlank(targetService)) {
        targetService = actualService;
      }

      if (StringUtils.isNotBlank(targetService)) {
        Service service = cluster.getService(targetService);
        StackId stackId = service.getDesiredStackId();

        ServiceInfo serviceInfo;
        try {
          serviceInfo = ambariMetaInfo.getService(stackId.getStackName(), stackId.getStackVersion(),
            targetService);
        } catch (StackAccessException se) {
          serviceInfo = null;
        }

        if (serviceInfo == null) {
          throw new AmbariException("Action " + actionRequest.getActionName() +
            " targets service " + targetService + " that does not exist.");
        }
      }

      String expectedComponent = actionDef.getTargetComponent() == null ? "" : actionDef.getTargetComponent();
      String actualComponent = resourceFilter == null || resourceFilter.getComponentName() == null ? "" : resourceFilter.getComponentName();
      if (!expectedComponent.isEmpty() && !actualComponent.isEmpty() && !expectedComponent.equals(actualComponent)) {
        throw new AmbariException("Action " + actionRequest.getActionName() + " targets component " + actualComponent +
          " that does not match with expected " + expectedComponent);
      }

      targetComponent = expectedComponent;
      if (StringUtils.isBlank(targetComponent)) {
        targetComponent = actualComponent;
      }

      if (StringUtils.isNotBlank(targetComponent) && StringUtils.isBlank(targetService)) {
        throw new AmbariException("Action " + actionRequest.getActionName() + " targets component " + targetComponent +
          " without specifying the target service.");
      }

      if (StringUtils.isNotBlank(targetComponent)) {
        Service service = cluster.getService(targetService);
        ServiceComponent component = service.getServiceComponent(targetComponent);
        StackId stackId = component.getDesiredStackId();

        ComponentInfo compInfo;
        try {
          compInfo = ambariMetaInfo.getComponent(stackId.getStackName(), stackId.getStackVersion(),
            targetService, targetComponent);
        } catch (StackAccessException se) {
          compInfo = null;
        }

        if (compInfo == null) {
          throw new AmbariException("Action " + actionRequest.getActionName() + " targets component " + targetComponent +
            " that does not exist.");
        }
      }
    }

    TargetHostType targetHostType = actionDef.getTargetType();

    if (TargetHostType.SPECIFIC.equals(targetHostType)
      || (targetService.isEmpty() && targetComponent.isEmpty())) {
      if ((resourceFilter == null || resourceFilter.getHostNames().size() == 0) && !isTargetHostTypeAllowsEmptyHosts(targetHostType)) {
        throw new AmbariException("Action " + actionRequest.getActionName() + " requires explicit target host(s)" +
          " that is not provided.");
      }
    }
  }
Validates the request to execute an action.
@param actionRequest
@throws AmbariException
ambari-server/src/main/java/org/apache/ambari/server/controller/AmbariActionExecutionHelper.java