kubernetes: Cannot access fieldRef for `spec.nodeName` or `status.podIP` through downwardAPI volume interface

Is this a BUG REPORT or FEATURE REQUEST?:

/kind bug

What happened:

Applying this Pod configuration:

apiVersion: v1
kind: Pod
metadata:
  name: dapi-files
spec:
  containers:
    - name: dapi-files
      image: superorbital/toolbox:latest
      command: ["sh", "-c"]
      args:
      - while true; do grep -H "" /etc/podinfo/*; sleep 5; done;
      volumeMounts:
        - name: podinfo
          mountPath: /etc/podinfo
          readOnly: true
  volumes:
    - name: podinfo
      downwardAPI:
        items:
          - path: "nodename"
            fieldRef:
              fieldPath: spec.nodeName
          - path: "address"
            fieldRef:
              fieldPath: status.podIP

Resulted in this error:

$ kubectl apply -f dapi-files.yaml
The Pod "dapi-files" is invalid:
* spec.volumes[0].downwardAPI.fieldRef.fieldPath: Unsupported value: "spec.nodeName": supported values: "metadata.annotations", "metadata.labels", "metadata.name", "metadata.namespace", "metadata.uid"
* spec.volumes[0].downwardAPI.fieldRef.fieldPath: Unsupported value: "status.podIP": supported values: "metadata.annotations", "metadata.labels", "metadata.name", "metadata.namespace", "metadata.uid"
* spec.containers[0].volumeMounts[0].name: Not found: "podinfo"

What you expected to happen:

I expected the Pod to run, with the nodename available in /etc/podinfo/nodename and the IP address available in /etc/podinfo/address.

How to reproduce it (as minimally and precisely as possible):

The above is about as minimal a reproduction as I can come up with.

Anything else we need to know?:

The documentation for the file based downwardAPI implies I should be able to access these values (emphasis added):

The following information is available to containers through environment variables and downwardAPI volumes:

Information available via fieldRef:

• spec.nodeName - the node’s name
• status.hostIP - the node’s IP
• metadata.name - the pod’s name
• metadata.namespace - the pod’s namespace
• status.podIP - the pod’s IP address
• spec.serviceAccountName - the pod’s service account name
• metadata.uid - the pod’s UID
• metadata.labels['<KEY>'] - the value of the pod’s label <KEY> (for example, metadata.labels['mylabel']); available in Kubernetes 1.9+
• metadata.annotations['<KEY>'] - the value of the pod’s annotation <KEY> (for example, metadata.annotations['myannotation']); available in Kubernetes 1.9+

However, kubectl explain seems to agree that those fieldRefs aren’t allowed:

$ kubectl explain pod.spec.volumes.downwardAPI.items.fieldRef
RESOURCE: fieldRef <Object>

DESCRIPTION:
     Required: Selects a field of the pod: only annotations, labels, name and
     namespace are supported.

     ObjectFieldSelector selects an APIVersioned field of an object.

FIELDS:
   apiVersion	<string>
     Version of the schema the FieldPath is written in terms of, defaults to
     "v1".

   fieldPath	<string> -required-
     Path of the field to select in the specified API version.

Maybe this is a documentation issue?

Environment:

• Kubernetes version (use kubectl version):

  Client Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.0", GitCommit:"925c127ec6b946659ad0fd596fa959be43f0cc05", GitTreeState:"clean", BuildDate:"2017-12-15T21:07:38Z", GoVersion:"go1.9.2", Compiler:"gc", Platform:"darwin/amd64"}
  Server Version: version.Info{Major:"1", Minor:"10+", GitVersion:"v1.10.2-gke.1", GitCommit:"75d2af854b1df023c7ce10a8795b85d3dd1f8d37", GitTreeState:"clean", BuildDate:"2018-05-10T17:23:18Z", GoVersion:"go1.9.3b4", Compiler:"gc", Platform:"linux/amd64"}
  

• Cloud provider or hardware configuration: GKE running 1.10
• OS (e.g. from /etc/os-release): Container-Optimized OS
• Kernel (e.g. uname -a): Linux gke-lab-default-pool-74632492-rnkr 4.4.111+
• Install tools:
• Others: