If an Elastic Compute Service (ECS) instance or a Container Service for Kubernetes (ACK) cluster does not have a public IP address, you can create an SNAT entry in the virtual private cloud (VPC) where the ECS instance or ACK cluster is deployed to enable Internet access. If Source Network Address Translation (SNAT) is disabled when you create a cluster, you can enable SNAT in the ACK console after the cluster is created. This topic describes how to enable SNAT for ACK clusters in the ACK console. SNAT allows ACK clusters to access the Internet.

Background information

You cannot call API operations to enable SNAT for existing clusters. For more information about SNAT, see What is NAT Gateway?.

Procedure

The following figure shows the steps to enable SNAT for an existing ACK cluster to access the Internet.

Enable SNAT
  1. Create a NAT gateway.
    1. Log on to the NAT Gateway console.
    2. In the left-side navigation pane, click NAT Gateway.
    3. On the NAT Gateway page, click Create NAT Gateway.
      For more information about the parameters, see Create NAT gateways.
      Note The NAT gateway must be created in the same region and VPC as the ACK cluster.
    After you create a NAT gateway, a route entry is automatically added to the route table of the VPC. The destination CIDR block of the route entry is 0.0.0.0/0 and the next hop is the NAT gateway. This ensures that traffic is routed to the NAT gateway.
    Notice By default, the route entry is automatically created for the first NAT gateway in the VPC. You must manually configure route entries if multiple NAT gateways are created in the VPC. For more information, see Create or delete route entries.
  2. Create an elastic IP address (EIP).
    In the left-side navigation pane, choose Elastic IP Addresses > Elastic IP Addresses. On the Elastic IP Addresses page, click Create EIP.

    If you already have an EIP, skip this step.

  3. Associate the EIP with the created NAT gateway.
    1. On the NAT Gateway page, find the newly created NAT gateway and choose 1 > Bind Elastic IP Address in the Actions column.
    2. In the Associate EIP dialog box, select a resource group from the Resource Group drop-down list and select the EIP that you created from the Select Existing EIPs drop-down list.
    3. Click OK.
  4. Create an SNAT entry for the NAT gateway.
    1. On the NAT Gateway page, find the newly created NAT gateway and click Manage in the Actions column.
    2. On the SNAT Management tab, click Create SNAT Entry.
    3. On the Create SNAT Entry page, set the parameters as described in the following table and click Confirm.
      For more information about the parameters, see Create a SNAT entry.
      Parameter Description
      SNAT Entry Select Specify VSwitch and select the vSwitches that are used by the cluster.
      • If the cluster uses Terway as the network plug-in, select the node vSwitches and pod vSwitches.
      • If the cluster uses Flannel as the network plug-in, select the node vSwitches.
      Perform the following steps to check the IDs of the vSwitches used by the cluster:
      1. Log on to the ACK console.
      2. In the left-side navigation pane, click Clusters. On the Clusters page, find the cluster that you want to manage and click its name or click Details in the Actions column.
      3. On the details page of the cluster, click the Cluster Resources tab to view the vSwitch IDs.
        Figure 1. Clusters that use Flannel
        Clusters that use Flannel
        Figure 2. Clusters that use Terway
        Clusters that use Terway
      Select Public IP Address Select a public IP address that is used to access the Internet.
    After the SNAT entry is created and SNAT rules are configured, SNAT is enabled for the cluster. You can log on to the NAT Gateway console to view the details of the NAT gateway, such as the EIP used by SNAT. The following figure shows a NAT gateway that is created for an ACK cluster that uses the Terway network plug-in. SNAT rules are configured to enable the cluster to access the Internet. NAT
    Click the name of the NAT gateway. On the SNAT Management tab of the details page, you can check whether the public IP address is associated with the vSwitches used by the cluster. The following figure shows the SNAT entries created for the cluster that uses the Terway network plug-in. snat

Result

Log on to a node of the cluster and access the Internet to verify that the node can access the Internet and no packet loss occurs during data transmission.

SNAT 2