Auto-rollback of failed upgrade fails with some resources

pkg/client/actionclient.go の 291 行目付近から始め、リンクされている issue 224 をコンテキストとして、自動 rollback のパスを追跡してください。Helm CLI の例を使って説明されている PVC と ConfigMap の失敗を再現し、その後、強制 rollback でこれらのリソースを復元できない場合に、失敗した upgrade が rollback ループに入らなくなっていることを確認してください。

It seems that helm's force option for rollbacks (that this library uses here) does not deal well with some resources.

When using the stackrox operator the error looks like this:

rollback failed: failed to replace object: PersistentVolumeClaim "scanner-v4-db" is invalid: spec: Forbidden: spec is immutable after creation except resources.requests and volumeAttributesClassName for bound claims
  core.PersistentVolumeClaimSpec{
      AccessModes:      {"ReadWriteOnce"},
      Selector:         nil,
      Resources:        {Requests: {s"storage": {i: {...}, s: "50Gi", Format: "BinarySI"}}},
-     VolumeName:       "pvc-a78c78d0-a692-47d6-b01a-be7f8d6ebd4a",
+     VolumeName:       "",
-     StorageClassName: &"standard-csi",
+     StorageClassName: nil,
      VolumeMode:       &"Filesystem",
      DataSource:       nil,
      ... // 2 identical fields
  }
: original upgrade error: cannot patch "scanner-v4-matcher-config" with kind ConfigMap:  "" is invalid: patch: Invalid value: "
{
  "apiVersion": "v1",
  "data": {
    "config.yaml": {
      "matcher": {
        "vulnerabilities_url": "https://central.stackrox.svc/api/extensions/scannerdefinitions?version=dev"
      }
    }
  },
  "kind": "ConfigMap",
  "metadata": {
[... snip ...]
  }
}": json: cannot unmarshal object into Go struct field ConfigMap.data of type string 

It may be easier to understand what is going on on the following example, since the issue also happens with helm CLI. It's just that while the CLI warns to exercise caution with this option, the helm-operator-plugins library uses force automatically and unconditionally.

Let's say I have a chart that contains just a PVC such as this:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc1
spec:
  accessModes:
  - ReadWriteOnce
{{- if .Values.badness }}
  storageClassName:
    nonsense: yes
{{- else }}
  storageClassName: standard
{{- end }}
  resources:
    requests:
      storage: 500Mi

Then I:

helm install --debug repro1 .

This works fine. Now I create any pod that uses the PVC to make it flip to a Bound state.

Then I try to apply a broken upgrade:

$ helm upgrade repro1 . --set badness=true
Error: UPGRADE FAILED: cannot patch "pvc1" with kind PersistentVolumeClaim:  "" is invalid: patch: Invalid value: "{\"apiVersion\":\"v1\",\"kind\":\"PersistentVolumeClaim\",\"metadata\":{\"annotations\":{\"meta.helm.sh/release-name\":\"repro1\",\"meta.helm.sh/release-namespace\":\"default\",\"pv.kubernetes.io/bind-completed\":\"yes\",\"pv.kubernetes.io/bound-by-controller\":\"yes\",\"volume.beta.kubernetes.io/storage-provisioner\":\"rancher.io/local-path\",\"volume.kubernetes.io/selected-node\":\"kind-control-plane\",\"volume.kubernetes.io/storage-provisioner\":\"rancher.io/local-path\"},\"creationTimestamp\":\"2025-02-13T12:00:25Z\",\"finalizers\":[\"kubernetes.io/pvc-protection\"],\"labels\":{\"app.kubernetes.io/managed-by\":\"Helm\"},\"managedFields\":[{\"manager\":\"helm\",\"operation\":\"Update\",\"apiVersion\":\"v1\",\"time\":\"2025-02-13T12:00:25Z\",\"fieldsType\":\"FieldsV1\",\"fieldsV1\":{\"f:metadata\":{\"f:annotations\":{\".\":{},\"f:meta.helm.sh/release-name\":{},\"f:meta.helm.sh/release-namespace\":{}},\"f:labels\":{\".\":{},\"f:app.kubernetes.io/managed-by\":{}}},\"f:spec\":{\"f:accessModes\":{},\"f:resources\":{\"f:requests\":{\".\":{},\"f:storage\":{}}},\"f:storageClassName\":{},\"f:volumeMode\":{}}}},{\"manager\":\"kube-scheduler\",\"operation\":\"Update\",\"apiVersion\":\"v1\",\"time\":\"2025-02-13T12:00:38Z\",\"fieldsType\":\"FieldsV1\",\"fieldsV1\":{\"f:metadata\":{\"f:annotations\":{\"f:volume.kubernetes.io/selected-node\":{}}}}},{\"manager\":\"kube-controller-manager\",\"operation\":\"Update\",\"apiVersion\":\"v1\",\"time\":\"2025-02-13T12:00:41Z\",\"fieldsType\":\"FieldsV1\",\"fieldsV1\":{\"f:metadata\":{\"f:annotations\":{\"f:pv.kubernetes.io/bind-completed\":{},\"f:pv.kubernetes.io/bound-by-controller\":{},\"f:volume.beta.kubernetes.io/storage-provisioner\":{},\"f:volume.kubernetes.io/storage-provisioner\":{}}},\"f:spec\":{\"f:volumeName\":{}}}},{\"manager\":\"kube-controller-manager\",\"operation\":\"Update\",\"apiVersion\":\"v1\",\"time\":\"2025-02-13T12:00:41Z\",\"fieldsType\":\"FieldsV1\",\"fieldsV1\":{\"f:status\":{\"f:accessModes\":{},\"f:capacity\":{\".\":{},\"f:storage\":{}},\"f:phase\":{}}},\"subresource\":\"status\"}],\"name\":\"pvc1\",\"namespace\":\"default\",\"resourceVersion\":\"764382\",\"uid\":\"75dd22fc-06ea-4ee0-b9e5-76eb054c3c62\"},\"spec\":{\"accessModes\":[\"ReadWriteOnce\"],\"resources\":{\"requests\":{\"storage\":\"500Mi\"}},\"storageClassName\":{\"nonsense\":true},\"volumeMode\":\"Filesystem\",\"volumeName\":\"pvc-75dd22fc-06ea-4ee0-b9e5-76eb054c3c62\"},\"status\":{\"phase\":\"Bound\",\"accessModes\":[\"ReadWriteOnce\"],\"capacity\":{\"storage\":\"500Mi\"}}}": json: cannot unmarshal object into Go struct field PersistentVolumeClaimSpec.spec.storageClassName of type string

This is expected. Now in this case the library would try to roll back, but with the force option this fails:

$ helm rollback repro1 1 --force
Error: failed to replace object: PersistentVolumeClaim "pvc1" is invalid: spec: Forbidden: spec is immutable after creation except resources.requests and volumeAttributesClassName for bound claims
  core.PersistentVolumeClaimSpec{
  	AccessModes:      {"ReadWriteOnce"},
  	Selector:         nil,
  	Resources:        {Requests: {s"storage": {i: {...}, s: "500Mi", Format: "BinarySI"}}},
- 	VolumeName:       "pvc-75dd22fc-06ea-4ee0-b9e5-76eb054c3c62",
+ 	VolumeName:       "",
  	StorageClassName: &"standard",
  	VolumeMode:       &"Filesystem",
  	... // 3 identical fields
  }

And then we fall into the loop as described in https://github.com/operator-framework/helm-operator-plugins/issues/224