InstanceGroupVFS Patch not implemented for vfs store

Error message

InstanceGroupVFS Patch not implemented for vfs store

What it means

The VFS-backed InstanceGroup client does not implement the Kubernetes-style Patch operation; the method always returns this error. Patching requires server-side apply/merge semantics the plain file store cannot provide. Use Update (read-modify-write) instead.

Source

Thrown at pkg/client/simple/vfsclientset/instancegroup.go:142

		return nil, err
	}
	return g, nil
}

func (c *InstanceGroupVFS) Delete(ctx context.Context, name string, options metav1.DeleteOptions) error {
	return c.delete(ctx, name, options)
}

func (r *InstanceGroupVFS) DeleteCollection(ctx context.Context, options metav1.DeleteOptions, listOptions metav1.ListOptions) error {
	return fmt.Errorf("InstanceGroupVFS DeleteCollection not implemented for vfs store")
}

func (r *InstanceGroupVFS) Watch(ctx context.Context, opts metav1.ListOptions) (watch.Interface, error) {
	return nil, fmt.Errorf("InstanceGroupVFS Watch not implemented for vfs store")
}

func (r *InstanceGroupVFS) Patch(ctx context.Context, name string, pt types.PatchType, data []byte, opts metav1.PatchOptions, subresources ...string) (result *kopsapi.InstanceGroup, err error) {
	return nil, fmt.Errorf("InstanceGroupVFS Patch not implemented for vfs store")
}

View on GitHub (pinned to 4c8573c808)

Solutions

Replace Patch with Get followed by modifying the field and Update to persist changes.
Perform patches through the Kubernetes API server (kops rolling-update / kubectl) instead of the VFS clientset.
Implement Patch in InstanceGroupVFS as read-modify-apply-update if you own the code.

Example fix

// before
ig, err := client.Patch(ctx, "nodes", types.StrategicMergePatchType, data, metav1.PatchOptions{})
// after
ig, err := client.Get(ctx, "nodes", metav1.GetOptions{})
if err != nil { return err }
ig.Spec.MachineType = "m5.large"
_, err = client.Update(ctx, ig, metav1.UpdateOptions{})

Defensive patterns

Strategy: fallback

Validate before calling

// avoid patch paths entirely on VFS stores
const vfsSupportsPatch = false
if vfsSupportsPatch { /* never */ }

Try / catch

result, err := igClient.Patch(ctx, name, pt, data, opts)
if err != nil && strings.Contains(err.Error(), "not implemented") {
  return getModifyUpdate(ctx, igClient, name, data)
}

Prevention

Use Get+Update (read-modify-write) with VFS stores.
Route patch operations through the API server instead of VFS.
Wrap the VFS clientset to hide unimplemented methods at compile time.

When it happens

Trigger: Calling Patch(ctx, name, patchType, data, opts, subresources...) on InstanceGroupVFS against a VFS state store.

Common situations: Tools using strategic-merge or JSON patch calls generated from client-go interfaces; automation that patches instance-group specs (e.g. updating node counts) via the VFS clientset.

Related errors

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/0dbcdfc4bf8d6fe1. Report an issue: GitHub.