How to migrate a cluster

This is a guide on how to restore a backup that was made from a different cluster, (i.e. cluster migration via restore).

To perform a basic restore (from a local backup), see How to restore a local backup.

Prerequisites

Restoring a backup from a previous cluster to a current cluster requires:

Apply cluster credentials

Passwords are not re-generated when a cluster is restored. To make sure the new cluster uses the credentials from the previous cluster, apply the credentials you saved during the backup process before restoring.

Create a secret with the password values you saved when creating the backup:

juju add-secret <secret name> monitoring=<password1> operator=<password2> replication=<password3> rewind=<password4>

where <secret name> can be any name you’d like for the restored secrets.

Then, grant the secret to the postgresql application that will initiate the restore:

juju grant-secret <secret name> postgresql

List backups

To view the available backups to restore, use the command list-backups:

juju run postgresql/leader list-backups

This shows a list of the available backups (it is up to you to identify which backup-id corresponds to the previous cluster):

backups: |-
  backup-id             | backup-type  | backup-status
  ----------------------------------------------------
  YYYY-MM-DDTHH:MM:SSZ  | physical     | finished

Restore backup

To restore your current cluster to the state of the previous cluster, run the restore command and pass the correct backup-id to the command:

juju run postgresql/leader restore backup-id=YYYY-MM-DDTHH:MM:SSZ

Your restore will then be in progress. Once it is complete, your current cluster will represent the state of the previous cluster.