I am using a POD directly to manage our C* cluster in a K8s cluster, not using any high-level controller. When I want to upgrade C*, I want to do an image update. Is this a good pattern to update image for an upgrade?
I saw the high-level deployment controller support image update too, but that causes the POD to delete and recreate, which in turn causes the IP to change. I don't want to change the IP and I found if I directly update the POD image, it can cause a restart and also keep the IP. This is the exact behavior I want, is this pattern right?
Is it safe to use in production?
I believe you can follow the K8s documentation for a more 'production ready' upgrade strategy. Basically, use the updateStrategy=RollingUpdate:
$ kubectl patch statefulset cassandra -p '{"spec":{"updateStrategy":{"type":"RollingUpdate"}}}and then update the image:
$ kubectl patch statefulset web --type='json' -p='[{"op": "replace", "path": "/spec/template/spec/containers/0/image", "value":"cassandra:next-version"}]'and watch your updates:
$ kubectl get pod -l app=cassandra -wThere's also Staging the Update in case you'd like to update each C* node individually, for example, why if the new version turns out to be incompatible, then you can revert that C* back to the original version.
Also, familiarize with all the Cassandra release notes before doing the upgrade.