Display PVC capacity usage using kubectl

[vkamra]

Feature Description

• One-line feature description (can be used as a release note): Display PVC capacity usage using kubectl top
• Primary contact (assignee): @vkamra
• Responsible SIGs: @kubernetes/sig-storage-feature-requests @kubernetes/sig-instrumentation-feature-requests
• Design proposal link (community repo):
• Reviewer(s) - (for LGTM) recommend having 2+ reviewers (at least one from code-area OWNERS file) agreed to review. Reviewers from multiple companies preferred:
  @jingxu97
• Approver (likely from SIG/area to which feature belongs): sig-instrumentation
• Feature target (which target equals to which milestone):
  • Alpha release target: 1.10
  • Beta release target: 1.11
  • Stable release target:

[fgrzadkowski]

Is there a design doc for this? The idea for kubectl top was to expose metrics available in master metric API. How would it work for PVCs?

I think this feature has to be approved by someone from @kubernetes/sig-instrumentation-feature-requests.

[idvoretskyi]

@vkamra any updates about the feature status?

[vkamra]

@idvoretskyi @fgrzadkowski - doc has the proposal.

PVC metrics are now available in the kubelet summary API (added in 1.8). @verult is working on adding these into the metrics exposed by heapster.

This would allow us to implement kubetl top pvc to display PVC resource usage in the cluster.

[vkamra]

We discussed status in storage-sig - the heapster changes are being worked on but kubectl changes (not designed/discussed yet) are not currently planned for 1.9. @verult @jingxu97 - can you also update?

[brancz]

I would very much prefer if we can not keep extending heapster, and instead maybe use the metrics-server for these purposes.

Also somewhat relevant: kubernetes/kubernetes#55489

[fgrzadkowski]

@vkamra This should NOT be added to heapster. As @brancz suggested it should be added to master metric API and metric server if needed. We need to move kubectl to using it anyway. It seems that the proposal hasn't been approved. I'd suggest to wait with the implementation for the approval. Also, as suggested earlier - please include @kubernetes/sig-instrumentation-feature-requests in this discussion.

[vkamra]

@brancz @fgrzadkowski - that makes sense to me.

Going to let @verult and @jingxu97 comment here as well because I believe they've had more recent discussions about this with members from the instrumentation sig and I might have mis-spoke about extending heapster.

Also added sig-instrumentation as approver.

[verult]

Yes we synced up with @DirectXMan12 recently and the consensus is that anything kubectl top consumes should go into the metric-server.

I'm still working on adding logic in Heapster because it's required to expose PVCStats to StackDriver (because metric-server doesn't support sinks like Heapster does).

[idvoretskyi]

@vkamra @jingxu97 @kubernetes/sig-storage-feature-requests @kubernetes/sig-instrumentation-feature-requests any progress is expected on this feature?

[brancz]

@idvoretskyi indirectly. We're currently working on getting kubectl top to use the metrics server at all (kubernetes/kubernetes#56206). Once that's done, we can think of PVC stats for the metrics server. I'll put it on the list of topics for the next sig meeting.

[idvoretskyi]

@brancz do you plan this still for 1.10 (or 1.11+ releases are more likely)?