Feature Overview (aka. Goal Summary)  

Allow customers to see the PVC storage usage with CLI.

That way users can prevent that the volume is filling up and even take action before impact is happening on production level.

We're adding this option into oc as experimental first while upstream is working on a kubectl implementation (which will take longer). We will remove the experimental flag when the kubectl option is available and replace it.

Goals (aka. expected user outcomes)

Get how much space is used by a PVC with oc command line. We're shipping this as an experimental option for oc (equivalent TP) because there is upstream work in kubectl and we can't know for sure that the output will be exactly the same. We will favor the kubectl implementation when available but we don't have a clear timeline.

Requirements (aka. Acceptance Criteria):

This feature will show how much space is used by a volume by querying the PVC (not the PV), also this PVC has to active (mounted to a pod). As we are going to rely on a kubectl plugins that queries metrics, the volume has to be attached to a pod.

Anyone reviewing this Feature needs to know which deployment configurations that the Feature will apply to (or not) once it's been completed.  Describe specific needs (or indicate N/A) for each of the following deployment scenarios. For specific configurations that are out-of-scope for a given release, ensure you provide the OCPSTRAT (for the future to be supported configuration) as well.

Use Cases (Optional):

As an OCP admin I want to visualize the storage consumed by active PVCs

As an OCP user/dev I want to visualize or monitor/set alerts on PVCs that are becoming full

Questions to Answer (Optional):

Question answered in the initial spike - STOR-1852

Out of Scope

Applies to PVC not PV

Applies to attached volume to running pods only

kubectl / upstream integration

Background

Although the metric is available it shouldn't require manual actions to see how much space is used by a PVC

Customer Considerations

This is for attached PVC, customers may want to have this for any PVC which would require investigations and changes in the metrics' retentions policy.

Documentation Considerations

There should be RN entry as well as a short section that shows how to query a PVC capacity usage. Also mention that this applies to attached PVCs only and it is TP.

Two ways:

Get the top PVCs usage

Query a specific PVC

Interoperability Considerations

There should not be any interoperability concerns.