feat: make postgres chart use different storage directories per major version

postgresql/Chart.yaml

@@ -2,5 +2,5 @@ apiVersion: v2
 name: postgresql
 description: Helm Chart for postgresql
 type: application
-version: 1.1.0
-appVersion: "15.2-alpine"
+version: 1.2.0
+appVersion: "15"

postgresql/templates/statefulset.yaml

@@ -44,7 +44,7 @@ spec:
         - name: postgresql
           securityContext:
             {{- toYaml .Values.securityContext | nindent 12 }}
-          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
+          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default (printf "%s-alpine" .Chart.AppVersion) }}"
           imagePullPolicy: {{ .Values.image.pullPolicy }}
           env:
             - name: POSTGRES_PASSWORD
@@ -79,6 +79,7 @@ spec:
           volumeMounts:
             - mountPath: "/var/lib/postgresql/data"
               name: data
+              subPath: {{ .Chart.AppVersion }}
             - mountPath: "/configs"
               name: config
             - mountPath: "/dev/shm"