ZK cluster post-install-upgrade hook does not wait for all replicas

[jkhalack]

Description

The post-install-upgrade hook in zookeeper cluster chart does verify that all desired replicas have been deployed.
Since it checks for status.replicas == status.readyReplicas, the hook might pass, for example, when only two of three desired replicas have been deployed successfully, before the third replica even started creating.

Importance

should-have

Location

https://github.com/pravega/zookeeper-operator/blob/v0.2.9/charts/zookeeper/templates/post-install-upgrade-hooks.yaml#L66

Suggestions for an improvement

The hook should rather use spec.replicas in the check instead of status.replicas, so that the number of ready replicas is compared to the desired number of replicas.