[Feature] Improvement Proposal for kubectl Custom Columns of etcd Resources

[vlerenc]

Feature (What you would like to be added):
I am not certain, what exactly the etcd resource READY column in the kubectl output depicts and find it confusing. At first, I was confused why all 3 pods must be ready for the etcd resource to become ready. What I care for as an operator is that the quorum is given and the etcd cluster is available/can serve requests. Only with second priority, I like to know what the state of the pods is, but for that I can also take a look at them directly or the statefulset. I saw that the etcd resource has a Quorate condition, which is probably what I am looking for. I would prefer to see that over the AllMembersReady condition. When I think about it, showing the BackupSucceeded condition would also make sense and not widen the kubectl output too much.

Then I noticed, that in some cases, it doesn't even mean what I thought it means, e.g. when I worked through the permanent quorum loss runbook, I noticed that my etcd resource is READY=false while it runs with 1 perfectly ready replica (before I need to scale it out to 3), even though etcd was up an serving requests just fine (I tested it with etcdctl).

I found that confusing and would welcome the following change:

• Show also the Quorate and BackupSucceeded conditions as columns in the kubectl output

Motivation (Why is this needed?):
As operator, I care more for those 2 conditions, then for the readiness condition, which I can look up also directly via pods or the statefulset.

[vlerenc]

P.S.: Personally, I use this command/alias now for etcd resources:

kubectl --namespace shoot get etcd -o=custom-columns='NAME:.metadata.name,DESIRED_REPLICAS:.status.clusterSize,ACTUAL_REPLICAS:.status.replicas,READY_REPLICAS:.status.readyReplicas,OVERALL_READY_STATUS:.status.ready,READY:.status.conditions[?(@.type=="AllMembersReady")].status,BACKUP:.status.conditions[?(@.type=="BackupReady")].status,QUOROM:.status.conditions[?(@.type=="Ready")].status'

...yielding:

NAME        DESIRED_REPLICAS   ACTUAL_REPLICAS   READY_REPLICAS   OVERALL_READY_STATUS   READY   BACKUP   QUOROM
etcd-main   3                  3                 3                true                   True    True     True

[ashwani2k]

Just a thought, so we can keep Quorate and BackupSucceeded as default output and may be we can implement a -o wide option like we recently did for MCM for the remaining columns.