Enable specifying PVC retention policy for auto deletion

[idanovinda]

Problem

Users can specify the number of instances in the manifest, both scaling up and scaling down. It creates the PVCs when there is a scaling up event. However, where there is a scaling down event, the control plane doesn't automatically delete the PVCs created for StatefulSets that are no longer needed. It requires manual checking and deletion to clean up the unused PVCs. As a result, unused PVCs continue to occupy storage resources, leading to potential inefficiencies and unnecessary costs.

Solution

In Kubernetes v1.23, a new feature has been introduced to address the issue of unused PVCs (see docs). The operator should set the retention policy in the Statefulsets of every clusters.

To specify the auto-deletion policy in the configmap, we can set:

persistent_volume_claim_retention_policy: "when_deleted:delete,when_scaled:delete"

while in the CRD configuration:

persistent_volume_claim_retention_policy: 
  when_deleted: "delete"
  when_scaled: "delete"

The default values are "retain" for "when_deleted" and "when_scaled".

[FxKu]

As we've already discussed in person, you could try to extend the scaling e2e test with checks if PVCs get removed or not

[SanjeevChoubey]

@idanovinda @FxKu this feature needed for us too , when we can expect this to be merged?

[SanjeevChoubey]

@idanovinda @FxKu this feature needed for us too , when we can expect this to be merged?

Can I pitch in and get this done, as we need this feature ASAP.

[FxKu]

👍

[idanovinda]

👍