Enabling Cluster Federation

You can enable cluster federation for a fleet with just a few clicks.

Enabling cluster federation involves two phases: enabling cluster federation and adding clusters to the federation. Enabling cluster federation for a fleet will federate the registered clusters in the fleet.

There is a quota limit for enabling cluster federation, and there are constraints on clusters in a fleet. Before enabling cluster federation, read the following constraints to avoid failures.

**Table 1** Cluster constraints
Item	Constraint
Cluster version	The versions of all clusters in the fleet must be 1.19 or later.
Cluster status	All clusters in the fleet must be in the Running status.
Cluster network	CCE clusters and CCE Turbo clusters: If a CCE cluster is located in AP-Singapore, UCS automatically creates a VPC endpoint in the VPC that the cluster belongs to when the federation is enabled. If a CCE cluster is not located in AP-Singapore, nodes in the cluster must be able to access the public network. For example, associate a public network address with a node to pull a public network image. Other clusters: Ensure that the clusters connect to UCS.
Quota	The cluster federation quota is 1. This means cluster federation can be enabled only for one fleet.

Log in to the UCS console. In the navigation pane, choose Fleets.
On the Fleets tab, locate the target fleet displayed with Federation not enabled. Click Enable.

Figure 1 Enabling cluster federation
In the displayed dialog box, click OK. Then, wait until cluster federation is enabled.
If the clusters in the fleet do not meet the constraints, an error message will be displayed. Modify the clusters as prompted and enable cluster federation again.

It takes about 10 minutes to enable cluster federation. You can click the federation status to view the detailed enabling progress. After cluster federation is enabled, a message indicating that cluster federation has been enabled and clusters have been federated is displayed on the top of the fleet.

Adding Clusters

After cluster federation is enabled for a fleet, you can continue to add clusters to the fleet. The new clusters are automatically federated. A federation can have a maximum of 20 clusters.

Log in to the UCS console. In the navigation pane, choose Fleets.
In the card view of the target fleet, click Add Cluster, or click in the upper right corner.
You can also click the fleet name to go to the fleet details page and click Add Cluster in the upper right corner of the Container Clusters page.
Select one or more existing clusters. A cluster can only be added to one fleet. The clusters displayed in the list are those have not been added to any fleet.

Ensure that the selected clusters meet the constraints described in Table 1. Otherwise, the clusters can be added to the fleet but fail to be federated. If clusters fail to be federated, perform operations in Why Cannot I Enable Cluster Federation for a Fleet or Register a Cluster to a Fleet After Cluster Federation Is Enabled?
Click OK.

Managing Federation

After cluster federation is enabled for a fleet, the Federation module on the fleet's details page is automatically unlocked.

Figure 2 Managing federation

Next, you can create federated resources such as federated workloads, Services, and storage for deploying your service. You can also perform advanced operations such as multi-active DR and auto scaling for multi-cluster applications.

Disabling Cluster Federation

If you do not need to use cluster federation, you can disable it. After cluster federation is disabled, services running on the workloads are not affected.

Log in to the UCS console. In the navigation pane, choose Fleets.
On the Fleets tab page, locate the target fleet and click Disable Federation in the upper right corner.

Figure 3 Disabling cluster federation
In the displayed dialog box, click OK.