fix read only fs?

deploy/redis/redis-sentinel-deploy.yaml

@@ -15,6 +15,16 @@ spec:
       labels:
         app: redis-sentinel
     spec:
+      # Init container to copy the sentinel.conf from the ConfigMap to a writable emptyDir volume.
+      initContainers:
+      - name: copy-sentinel-config
+        image: busybox
+        command: ['sh', '-c', 'cp /config/sentinel.conf /writable/']
+        volumeMounts:
+        - name: sentinel-config-readonly
+          mountPath: /config
+        - name: sentinel-config
+          mountPath: /writable
       containers:
       - name: redis-sentinel
         image: redis:6.2-alpine
@@ -26,8 +36,12 @@ spec:
           - "/etc/redis/sentinel.conf"
         volumeMounts:
         - name: sentinel-config
-          mountPath: /etc/redis
+          mountPath: /etc/redis  # this volume is now writable
       volumes:
-      - name: sentinel-config
+      # Mount the ConfigMap as a read-only volume for the init container
+      - name: sentinel-config-readonly
         configMap:
           name: redis-sentinel-config
+      # EmptyDir volume to hold the writable config file
+      - name: sentinel-config
+        emptyDir: {}