# external-snapshotter (CSI snapshot control plane)

Installs the cluster-singleton [kubernetes-csi/external-snapshotter](https://github.com/kubernetes-csi/external-snapshotter):

- the `snapshot.storage.k8s.io` CRDs — `VolumeSnapshot`, `VolumeSnapshotContent`,
  `VolumeSnapshotClass` (v1, GA);
- the **snapshot-controller** Deployment (into `kube-system`, the upstream default) that
  reconciles those objects against any CSI driver's `CreateSnapshot`/`DeleteSnapshot`.

Neither k3s nor the Longhorn chart ships this. It is a prerequisite for:

1. **`VolumeSnapshotClass` (driver.longhorn.io)** — see
   `../longhorn/volumesnapshotclass.yaml` (applied by `platform-config`).
2. **CDI snapshot smart-clone** — the CDI `StorageProfile`s set `cloneStrategy: snapshot`
   (see `../kubevirt/cdi-storageprofiles.yaml`); CDI clones VM disks by taking a CSI
   `VolumeSnapshot` instead of a slow host-assisted byte copy.
3. Clearing the **`CDIDefaultStorageClassDegraded`** alert — a default virtualization
   StorageClass must support *both* smart-clone *and* ReadWriteMany.

## Wiring

- **Pass:** `platform` (controllers). Registers the CRDs.
- The `VolumeSnapshotClass` CR that consumes the CRDs lives in the `platform-config` pass
  (`dependsOn: platform`), per the controllers/configs split.
- The CDI `StorageProfile`s live one pass further out, in `platform-config-cdi`
  (`dependsOn: platform-config`) — `storageprofiles.cdi.kubevirt.io` is created by cdi-operator only
  after it reconciles the `CDI` CR, so they cannot share a pass with it. See
  `clusters/base/platform-config-cdi.yaml`.

## Version

Pinned to **v8.2.0** (Renovate-maintained). The v8.x line aligned to Kubernetes 1.31 at
v8.1.0; this cluster is now k3s v1.36.4, so the pin should be **re-checked for 1.36** (a newer
external-snapshotter line may be the version-matched choice) — do not treat v8.2.0 as verified
against 1.36 yet. The snapshot-controller image is re-pinned to the same tag via the kustomization
`images` transformer (the upstream setup manifest lags on the image tag).