we have couchbase cluster deployed on Openshift. Couchbase web console is opening but we are not able to add buckets to it. For that we have to mention buckets in Ymal file and then redeploy using openshift operator. Is it the general behavior or we can add buckets without re-deployment of cluster ??
Yes, that's the intended behavior. Much of the cluster management, like buckets and adding of nodes, is under the control of the operator.
It is possible to disable bucket management if you have a need to, but the intent is that you'll operate through kubectl.