feat: Add fsGroup support on CSI driver

deploy/helm/csi-wekafsplugin/templates/driver.yaml

@@ -11,3 +11,6 @@ spec:
   podInfoOnMount: true
   volumeLifecycleModes:
     - Persistent
+  {{- if semverCompare ">=1.19.0" .Capabilities.KubeVersion.Version }}
+  fsGroupPolicy: File
+  {{- end }}

examples/fsgroup/README.md

@@ -0,0 +1,27 @@
+# Overview
+## Example Intentions
+1. This example concentrates on setting fsGroup on Weka CSI volume
+2. The example makes a use of a directory-backed volume, but the feature is functional on any other type of volume backings
+
+## Weka CSI Plugin Upgrade Implications
+Since CSIDriver objects are immutable, adding support for fsGroup requires the plugin to be uninstalled and reinstalled.
+> **NOTE:** Existing persistent volumes or workloads using them will not be affected
+
+# Workflow
+> All commands below may be executed by `kubectl apply -f <FILE>.yaml`
+1. Create storageclass `storageclass-wekafs-snap-api` (Located in [../dynamic_directory/storageclass-wekafs-dir-api.yaml](../dynamic_directory/storageclass-wekafs-dir-api.yaml))
+2. Create CSI secret `csi-wekafs-api-secret`  (Located in [../common/csi-wekafs-api-secret.yaml](../common/csi-wekafs-api-secret.yaml)) 
+3. Provision a new volume `pvc-wekafs-fsgroup`
+4. Create application that writes timestamp every 10 seconds into `/data/temp.txt`: `csi-app-fsgroup` and has different non-root permissions
+5. Attach to the application and validate filesystem contents and permissions by issuing 
+   ```
+   kubectl exec csi-app-fsgroup -- ls -al /data
+   ```
+   The output should resemble this:
+   ```
+   $ ls -al /data
+   total 8
+   drwxrws--- 1 root 2000    0 Feb 12 11:46 .
+   drwxr-xr-x 1 root root 4096 Feb 12 11:46 ..
+   -rw-r--r-- 1 2000 2000 2345 Feb 12 11:57 temp.txt
+   ```

examples/fsgroup/csi-app-fsgroup.yaml

@@ -0,0 +1,25 @@
+kind: Pod
+apiVersion: v1
+metadata:
+  name: csi-app-fsgroup
+spec:
+  securityContext:
+    runAsUser: 2000
+    runAsGroup: 2000
+    fsGroup: 2000
+  # make sure that pod is scheduled only on node having weka CSI node running
+  nodeSelector:
+    topology.csi.weka.io/global: "true"
+  containers:
+    - name: my-frontend
+      image: ubuntu
+      volumeMounts:
+      - mountPath: "/data"
+        name: my-csi-volume
+      command: ["/bin/sh"]
+      args: ["-c", "while true; do echo `date` hello >> /data/temp.txt; sleep 10;done"]
+  terminationGracePeriodSeconds: 1
+  volumes:
+    - name: my-csi-volume
+      persistentVolumeClaim:
+        claimName: pvc-wekafs-fsgroup # defined in pvc-wekafs-dir-api.yaml

examples/fsgroup/pvc-wekafs-fsgroup.yaml

@@ -0,0 +1,12 @@
+kind: PersistentVolumeClaim
+apiVersion: v1
+metadata:
+  name: pvc-wekafs-fsgroup
+spec:
+  accessModes:
+    - ReadWriteMany
+  storageClassName: storageclass-wekafs-snap-api
+  volumeMode: Filesystem
+  resources:
+    requests:
+      storage: 1Gi