protected DomainRouterVO findElbVmForLb(FirewallRule lb) { // TODO: use a table to lookup
   ElasticLbVmMapVO map = _elbVmMapDao.findOneByIp(lb.getSourceIpAddressId());
   if (map == null) {
     return null;
   }
   DomainRouterVO elbVm = _routerDao.findById(map.getElbVmId());
   return elbVm;
 }
  @Override
  @DB
  public LoadBalancer handleCreateLoadBalancerRule(
      CreateLoadBalancerRuleCmd lb, Account account, long networkId)
      throws InsufficientAddressCapacityException, NetworkRuleConflictException {
    // this part of code is executed when the LB provider is Elastic Load Balancer vm
    if (!_networkModel.isProviderSupportServiceInNetwork(
        lb.getNetworkId(), Service.Lb, Provider.ElasticLoadBalancerVm)) {
      return null;
    }

    Long ipId = lb.getSourceIpAddressId();
    if (ipId != null) {
      return null;
    }
    boolean newIp = false;
    account = _accountDao.acquireInLockTable(account.getId());
    if (account == null) {
      s_logger.warn("ELB: CreateLoadBalancer: Failed to acquire lock on account");
      throw new CloudRuntimeException("Failed to acquire lock on account");
    }
    try {
      List<LoadBalancerVO> existingLbs =
          findExistingLoadBalancers(
              lb.getName(),
              lb.getSourceIpAddressId(),
              lb.getAccountId(),
              lb.getDomainId(),
              lb.getSourcePortStart());
      if (existingLbs == null) {
        existingLbs =
            findExistingLoadBalancers(
                lb.getName(), lb.getSourceIpAddressId(), lb.getAccountId(), lb.getDomainId(), null);
        if (existingLbs == null) {
          if (lb.getSourceIpAddressId() != null) {
            existingLbs =
                findExistingLoadBalancers(
                    lb.getName(), null, lb.getAccountId(), lb.getDomainId(), null);
            if (existingLbs != null) {
              throw new InvalidParameterValueException(
                  "Supplied LB name "
                      + lb.getName()
                      + " is not associated with IP "
                      + lb.getSourceIpAddressId());
            }
          } else {
            s_logger.debug(
                "Could not find any existing frontend ips for this account for this LB rule, acquiring a new frontent IP for ELB");
            PublicIp ip = allocDirectIp(account, networkId);
            ipId = ip.getId();
            newIp = true;
          }
        } else {
          ipId = existingLbs.get(0).getSourceIpAddressId();
          s_logger.debug(
              "ELB: Found existing frontend ip for this account for this LB rule " + ipId);
        }
      } else {
        s_logger.warn("ELB: Found existing load balancers matching requested new LB");
        throw new NetworkRuleConflictException(
            "ELB: Found existing load balancers matching requested new LB");
      }

      Network network = _networkModel.getNetwork(networkId);
      IPAddressVO ipAddr = _ipAddressDao.findById(ipId);

      LoadBalancer result = null;
      try {
        lb.setSourceIpAddressId(ipId);
        result = _lbMgr.createLoadBalancer(lb, false);
      } catch (NetworkRuleConflictException e) {
        s_logger.warn("Failed to create LB rule, not continuing with ELB deployment");
        if (newIp) {
          releaseIp(ipId, UserContext.current().getCallerUserId(), account);
        }
        throw e;
      }

      DomainRouterVO elbVm = null;

      if (existingLbs == null) {
        elbVm = findELBVmWithCapacity(network, ipAddr);
        if (elbVm == null) {
          elbVm = deployLoadBalancerVM(networkId, ipAddr, account.getId());
          if (elbVm == null) {
            s_logger.warn(
                "Failed to deploy a new ELB vm for ip "
                    + ipAddr
                    + " in network "
                    + network
                    + "lb name="
                    + lb.getName());
            if (newIp) releaseIp(ipId, UserContext.current().getCallerUserId(), account);
          }
        }

      } else {
        ElasticLbVmMapVO elbVmMap = _elbVmMapDao.findOneByIp(ipId);
        if (elbVmMap != null) {
          elbVm = _routerDao.findById(elbVmMap.getElbVmId());
        }
      }

      if (elbVm == null) {
        s_logger.warn("No ELB VM can be found or deployed");
        s_logger.warn("Deleting LB since we failed to deploy ELB VM");
        _lbDao.remove(result.getId());
        return null;
      }

      ElasticLbVmMapVO mapping = new ElasticLbVmMapVO(ipId, elbVm.getId(), result.getId());
      _elbVmMapDao.persist(mapping);
      return result;

    } finally {
      if (account != null) {
        _accountDao.releaseFromLockTable(account.getId());
      }
    }
  }