Matthew L Daniels answer describes the valid approach of querying the kubernetes api using the nodename which is obtained by an env var. The difficulty lies in giving the pod the proper rbac access and setting up an init Container.

Here the kubernetes yml that implements this with an init container using the python kubernetes client:

### This serviceAccount gives the kafka sidecar the permission to query the kubernetes API for node information so that it can find out the advertise host (node public dns name) for the kafka which uses hostPort to be as efficient as possible.
apiVersion: v1
kind: ServiceAccount
metadata:
  name: node-reader-service-account
  namespace: default
---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: node-reader-cluster-role
rules:
  - apiGroups: [""] # The API group "" indicates the core API Group.
    resources: ["nodes"]
    verbs: ["get", "list", "watch"]

---

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: read-nodes-rolebinding
subjects:
  - kind: ServiceAccount # May be "User", "Group" or "ServiceAccount"
    name: node-reader-service-account
    namespace: default 
roleRef:
  kind: ClusterRole
  name: node-reader-cluster-role
  apiGroup: rbac.authorization.k8s.io

---

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  annotations:
  creationTimestamp: null
  labels:
    io.kompose.service: kafka
  name: kafka
spec:
  replicas: 1
  strategy:
    type: Recreate
  template:
    metadata:
      creationTimestamp: null
      labels:
        io.kompose.service: kafka
    spec:
      serviceAccountName: node-reader-service-account
      containers:

      - name: kafka
        image: someImage
        resources: {}
        command: ["/bin/sh"]
        args: ["-c", "export KAFKA_ADVERTISED_LISTENERS=$(cat '/etc/sidecar-data/dnsName') && env | grep KAFKA_ADVERTISED_LISTENERS && /start-kafka.sh"]
        volumeMounts:
        - name: sidecar-data
          mountPath: /etc/sidecar-data/

      initContainers:
      - name: kafka-sidecar
        image: sidecarImage
        command: ["python"]
        args: ["/script/getHostDnsName.py", "$(KUBE_NODE_NAME)", "/etc/sidecar-data/dnsName"]
        env:
          - name: KUBE_NODE_NAME
            valueFrom:
              fieldRef:
                fieldPath: spec.nodeName
        volumeMounts:
        - name: sidecar-data
          mountPath: /etc/sidecar-data/

      volumes:
      - name: sidecar-data
        emptyDir: {}

      restartPolicy: Always
status: {}