It should be possible for Infinispan clusters to be upgraded to the latest .patch release with zero-downtime.

The expectation is that consuming applications using the Operator will not skip patch releases and upgrade .N -> 0.N+1 -> .N...

In the case of Keycloak every patch release will not always be consumed so it's necessary for us to ensure that if .N -> .N+2 is somehow broken, despite our testing of .N -> N+1 compatibility, we will release .N+3 which allows .N -> .N+3 zero-downtime upgrades.

ISPN-9622 will ensure wire compatibility within Infinispan. To ensure compatibility of command semantic changes between versions, we will introduce new commands e.g. CommandName becomes CommandName2 and introduce a new method in the interceptors to handle the new semantics.

Not supported:

• JGroups stack changes
• Cache configuration changes