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HPA shown as "Missing" in Rancher UI due to API version mismatch

Article Number: 000022208

Environment

  • Rancher Prime
  • Kubernetes 1.23+

Situation

In the Apps interface in the Rancher UI, Horizontal Pod Autoscalers (HPAs) for some installed apps display a "Missing" state, even though the HPAs are active and functioning correctly.

Cause

In Kubernetes 1.23 and later, the autoscaling API group has a preferred version of v2.

When a autoscaling resource (such as a HPA) is deployed using the autoscaling/v1 API, the Kubernetes API server accepts the request and silently migrates this resource to autoscaling/v2.

Rancher tracks resources associated with an App using the app.catalog.cattle.io custom resource. Because the Helm chart specified v1 during deployment, the app.catalog.cattle.io object records the HPA resource version as autoscaling/v1.

Rancher's cluster cache in newer versions watches for autoscaling/v2 resources, due to the preferred apiVersion. The UI attempts to look up the autoscaling/v1 object defined in the App metadata, but since the cache contains only autoscaling/v2 objects, the lookup fails, resulting in the "Missing" status.

Resolution

Temporary workaround

  1. Edit the app.catalog.cattle.io object and set apiVersion for the HPA under spec.resources to autoscaling/v2:

kubectl edit app.catalog.cattle.io <app-name> -n <namespace>
2. Locate the spec.resources section. Find the entry corresponding to the HorizontalPodAutoscaler

- apiVersion: autoscaling/v1
  kind: HorizontalPodAutoscaler
  name: <hpa-name>
  namespace: <namespace>
3. Change the apiVersion to autoscaling/v2

- apiVersion: autoscaling/v2  # Updated from v1
  kind: HorizontalPodAutoscaler
  name: <hpa-name>
  namespace: <namespace>
4. Save and exit the editor 5. Refresh the Rancher UI

The HPA should now transition to an "Active" state in the Apps view.

Note: This change will be reverted if the Helm release is upgraded or rolled back

Permanent Solution

The underlying Helm chart must be updated by the chart maintainer.

  1. Update the Helm chart templates to use autoscaling/v2 for HorizontalPodAutoscaler resources.
  2. Publish the updated chart.
  3. Upgrade the App in Rancher using the new chart version, this ensures the app.catalog.cattle.io resource is created with the correct v2 metadata automatically.