This topic describes upgrade procedures for multi-cluster v2 deployments. See Multi-cluster deployments (v2) for the introduction and Concepts for multi-cluster deployments (v2) for the architecture overview.
Patch upgrades can be deployed with zero-downtime.
Deploying different Keycloak major/minor versions on each of the sites is not supported. It is technically possible for upgrades to be rolled out to both sites simultaneously, however we recommend that upgrades be rolled out to one site at a time in order to simplify monitoring and debugging. Rollouts in the different sites should be done promptly to avoid older sites writing data that other sites assume to be already migrated.
For major or minor version upgrades:
Shut down all sites except one.
Deploy the new minor or major version in one site and verify the installation.
Deploy the new version in all other sites.
Follow your database vendor’s zero-downtime upgrade procedure, and possibly combine it with a Keycloak upgrade. Ensure that synchronous replication remains configured after the upgrade, as disabling synchronous replication can lead to data loss during failover. Verify that the Multi-cluster deployments (v2) infrastructure requirements continue to be met after the upgrade.