fix volume sub_path for init containers

Change-Id: I43ed3ac96220a6af44ec08e1689a131d746b10b9

kubernetes/files/rc.yml

@@ -32,6 +32,9 @@ spec:
             "volumeMounts": [
                 {
                     "name": "{{ volume.name }}",
+                    {%- if volume.sub_path is defined %}
+                    "subPath": "{{ volume.sub_path }}",
+                    {%- endif %}
                     "mountPath": "{{ volume.mount }}"
                 }
             ]
@@ -161,4 +164,4 @@ spec:
       {%- if service.image_pull_secretes is defined %}
       imagePullSecrets:
         - name: {{ service.image_pull_secretes }}
-      {%- endif %}
+      {%- endif %}