@Override
  public Map<Long, Host> getHostIdsForCluster(String clusterName)
      throws AmbariException {
    Map<Long, Host> hosts = new HashMap<>();

    for (Host h : getClusterHostsMap().get(clusterName)) {
      HostEntity hostEntity = hostDAO.findByName(h.getHostName());
      hosts.put(hostEntity.getHostId(), h);
    }

    return hosts;
  }
Attempts to map the host to the cluster via clusterhostmapping table if not already present, and add a host_version
record for the cluster's currently applied (stack, version) if not already present.
@param hostname Host name
@param clusterName Cluster name
@throws AmbariException May throw a DuplicateResourceException.
ambari-server/src/main/java/org/apache/ambari/server/state/cluster/ClustersImpl.java