docs: add faq

Add fast answers to common questions

Signed-off-by: Serge Logvinov <[email protected]>

README.md

@@ -319,6 +319,10 @@ spec:
     - topology.kubernetes.io/zone
 ```
 
+## FAQ
+
+See [FAQ](docs/faq.md) for answers to common questions.
+
 ## Resources
 
 * https://arslan.io/2018/06/21/how-to-write-a-container-storage-interface-csi-plugin/

docs/faq.md

@@ -0,0 +1,76 @@
+# Fast answers to common questions
+
+## Create a PVC with already existing disk
+
+If you have a disk already created in Proxmox, you can use it with the CSI plugin.
+First, you need to create a PV/PVC with the disk name and the storage class name.
+The size of the PersistentVolume must be the same as the disk size.
+
+```yaml
+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  name: pvc-test
+spec:
+  accessModes:
+    - ReadWriteOnce
+  capacity:
+    storage: 10Gi
+  csi:
+    driver: csi.proxmox.sinextra.dev
+    fsType: xfs
+    volumeAttributes:
+      storage: zfs
+    volumeHandle: dev-1/pve-m-4/zfs/vm-100-disk-1
+  storageClassName: proxmox-zfs
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: storage-test-0
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 10Gi
+  storageClassName: proxmox-zfs
+  volumeName: pvc-test
+```
+
+The disk name is `vm-100-disk-1`, and the storage class name is `proxmox-zfs`.
+
+## How to change the disk secret key?
+
+The secret key cannot be change through kubernetes API, but you can use the following instructions.
+Before starting, read the good explanation of the [cryptsetup](https://wiki.archlinux.org/title/Dm-crypt/Device_encryption) tool.
+
+First, you need to run the pod with secured PVC, then you need to define the csi-plugin pod running on the same node as the pod with the PVC.
+
+Lets say the csi-plugin pod name is `proxmox-csi-plugin-node-hjchn` and `/dev/sdb` is the disk you want to change the secret key for.
+
+```shell
+# Check the disk
+kubectl -n csi-proxmox exec -ti proxmox-csi-plugin-node-hjchn -- /sbin/cryptsetup luksDump /dev/sdb
+# Check the passphrase
+kubectl -n csi-proxmox exec -ti proxmox-csi-plugin-node-hjchn -- /sbin/cryptsetup luksOpen --test-passphrase -v /dev/sdb
+```
+
+Add the new passphrase to the disk
+
+```shell
+# Add the new passphrase
+kubectl -n csi-proxmox exec -ti proxmox-csi-plugin-node-hjchn -- /sbin/cryptsetup luksAddKey /dev/sdb
+# Check the new passphrase
+kubectl -n csi-proxmox exec -ti proxmox-csi-plugin-node-hjchn -- /sbin/cryptsetup luksOpen --test-passphrase -v /dev/sdb
+# Check the disk
+kubectl -n csi-proxmox exec -ti proxmox-csi-plugin-node-hjchn -- /sbin/cryptsetup luksDump /dev/sdb
+```
+
+After you have added the new passphrase, you can remove the old one.
+And change the passphrase in kubernetes secret resource.
+
+```shell
+# Remove the old passphrase
+kubectl -n csi-proxmox exec -ti proxmox-csi-plugin-node-hjchn -- /sbin/cryptsetup luksRemoveKey /dev/sdb
+```