[stable/opencart] Fix chart not being upgradable

stable/opencart/Chart.yaml

@@ -1,5 +1,5 @@
 name: opencart
-version: 2.0.4
+version: 3.0.0
 appVersion: 3.0.2-0
 description: A free and open source e-commerce platform for online merchants. It provides
   a professional and reliable foundation for a successful online store.

stable/opencart/README.md

@@ -123,3 +123,15 @@ The [Bitnami OpenCart](https://github.com/bitnami/bitnami-docker-opencart) image
 
 Persistent Volume Claims are used to keep the data across deployments. This is known to work in GCE, AWS, and minikube.
 See the [Configuration](#configuration) section to configure the PVC or to disable persistence.
+
+## Upgrading
+
+### To 3.0.0
+
+Backwards compatibility is not guaranteed unless you modify the labels used on the chart's deployments.
+Use the workaround below to upgrade from versions previous to 3.0.0. The following example assumes that the release name is opencart:
+
+```console
+$ kubectl patch deployment opencart-opencart --type=json -p='[{"op": "remove", "path": "/spec/selector/matchLabels/app"}]'
+$ kubectl delete statefulset opencart-mariadb --cascade=false
+```

stable/opencart/templates/deployment.yaml

@@ -9,6 +9,10 @@ metadata:
     release: "{{ .Release.Name }}"
     heritage: "{{ .Release.Service }}"
 spec:
+  selector:
+    matchLabels:
+      app: {{ template "opencart.fullname" . }}
+      release: "{{ .Release.Name }}"
   template:
     metadata:
       labels: