Bind kubernetes pods to hostnames

Question

I have a simple k8s deployment.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: test-deployment
  labels:
    app: test
spec:
  replicas: 3
  selector:
    matchLabels:
      app: test
  template:
    metadata:
      labels:
        app: test
    spec:
      containers:
        - name: test-container
          image: centos:7
          command: ["/bin/sh"]
          args: ["-c", "tail -f /dev/null"]

These lead to creation of pods that look like this:

NAME                               READY   STATUS    RESTARTS   AGE
test-deployment-59bb6b8b4d-pnfg8   1/1     Running   0          11m
test-deployment-59bb6b8b4d-s7w8x   1/1     Running   0          11m
test-deployment-59bb6b8b4d-wvw7n   1/1     Running   0          11m

By default, the hostnames corresponding to each of these match the pod names.

>> kubectl exec test-deployment-59bb6b8b4d-pnfg8 -c test-container env | grep HOSTNAME
HOSTNAME=test-deployment-59bb6b8b4d-pnfg8
>> kubectl exec test-deployment-59bb6b8b4d-s7w8x -c test-container env | grep HOSTNAME
HOSTNAME=test-deployment-59bb6b8b4d-s7w8x
>> kubectl exec test-deployment-59bb6b8b4d-wvw7n -c test-container env | grep HOSTNAME
HOSTNAME=test-deployment-59bb6b8b4d-wvw7n

Here's my question. Is there a way, I could pre-configure the hostnames so that they look something like this?

>> kubectl exec test-deployment-59bb6b8b4d-pnfg8 -c test-container env | grep HOSTNAME
HOSTNAME=test-deployment-pod1
>> kubectl exec test-deployment-59bb6b8b4d-s7w8x -c test-container env | grep HOSTNAME
HOSTNAME=test-deployment-pod2
>> kubectl exec test-deployment-59bb6b8b4d-wvw7n -c test-container env | grep HOSTNAME
HOSTNAME=test-deployment-pod3

The expectation would also be that when a pod dies down and is replaced, the new pod binds back to the hostname that the older one was mapped to.

Thanks in advance!

Answer 1

Use StatefulSet instead of Deployment