Switch over a PostgreSQL cluster

You can initiate a switchover for a PostgreSQL Replication Cluster by executing the kbcli or kubectl command. Then KubeBlocks modifies the instance roles.

Before you start

• Make sure the cluster is running normally.

• Check whether the following role probe parameters exist to verify whether the role probe is enabled.

  kubectl get cd postgresql -o yaml
  >
  probes:
    roleProbe:
      failureThreshold: 2
      periodSeconds: 1
      timeoutSeconds: 1

Initiate the switchover

You can switch over a secondary of a PostgreSQL Replication Cluster to the primary role, and the former primary instance to a secondary.

kbcli

• Switchover with no primary instance specified

  kbcli cluster promote mycluster -n demo

• Switchover with a specified new primary instance

  kbcli cluster promote mycluster -n demo --instance='mycluster-postgresql-2'

• If there are multiple components, you can use --components to specify a component.

  kbcli cluster promote mycluster -n demo --instance='mycluster-postgresql-2' --components='postgresql'

kubectl

The value of instanceName decides whether a new primary instance is specified for the switchover.

• Switchover with no specified primary instance

  kubectl apply -f -<<EOF
  apiVersion: apps.kubeblocks.io/v1alpha1
  kind: OpsRequest
  metadata:
    name: mycluster-switchover
    namespace: demo
  spec:
    clusterName: mycluster
    type: Switchover
    switchover:
    - componentName: postgresql
      instanceName: '*'
  >>

• Switchover with a specified new primary instance

  kubectl apply -f -<<EOF
  apiVersion: apps.kubeblocks.io/v1alpha1
  kind: OpsRequest
  metadata:
    name: mycluster-switchover
    namespace: demo
  spec:
    clusterName: mycluster
    type: Switchover
    switchover:
    - componentName: postgresql
      instanceName: 'mycluster-postgresql-2'
  >>

Verify the switchover

Check the instance status to verify whether the switchover is performed successfully.

kbcli

kbcli cluster list-instances -n demo

kubectl

kubectl get cluster mycluster -n demo

kubectl -n demo get po -L kubeblocks.io/role 

Handle an exception

If an error occurs, refer to Handle an exception to troubleshoot the operation.