Downward API vs. metadata.labels

Issue

• According to https://access.redhat.com/documentation/en/openshift-enterprise/version-3.2/developer-guide/#selecting-fields metadata.labels should be a valid selector. Trying to use this fieldPath leads to an error:

$ oc create -f pod.yaml
The Pod "test-pod" is invalid.
spec.containers[0].env[0].valueFrom.fieldRef.fieldPath: Unsupported value: "metadata.labels": supported values: metadata.name, metadata.namespace, status.podIP

#cat pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: test-pod
spec:
  containers:
    - name: test-container
      image: reverse-proxy/reverse-proxy
      command: [ "/bin/sh", "-c", "env" ]
      env:
        - name: POD_LABELS
          valueFrom:
            fieldRef:
              fieldPath: metadata.labels
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
  restartPolicy: Never