Configuring /etc/hosts/in Kubernetes Depolyment/Pod

Example of Pod:

apiVersion: v1
kind: Pod
metadata:
  name: hostaliases-pod
spec:
  restartPolicy: Never
  hostAliases:
  - ip: "127.0.0.1"
    hostnames:
    - "foo.local"
    - "bar.local"
  - ip: "10.1.2.3"
    hostnames:
    - "foo.remote"
    - "bar.remote"
  containers:
  - name: cat-hosts
    image: busybox
    command:
    - cat
    args:
    - "/etc/hosts"

Example of Deployment

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: hostaliases-deployment
spec:
  template:
    spec:
      hostAliases:
      - ip: "127.0.0.1"
        hostnames:
        - "foo.local"
        - "bar.local"
      - ip: "10.1.2.3"
        hostnames:
        - "foo.remote"
        - "bar.remote"
      containers:
      - name: a-aspnetcore-app
        image: aspnetcore-app:v1.0.0
        env:
        - name: ASPNETCORE_ENVIRONMENT
          value: Development
        ports:
        - containerPort: 80
      imagePullSecrets:
      - name: docker-secret

See the result in Kubernetes container

# cat /etc/hosts
# Kubernetes-managed hosts file.
127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
fe00::0 ip6-mcastprefix
fe00::1 ip6-allnodes
fe00::2 ip6-allrouters
192.168.240.234 hostaliases-deployment-65d5c48f7c-pqqvn

# Entries added by HostAliases.
127.0.0.1       foo.local bar.local
10.1.2.3        foo.remote bar.remote

reference: add-entries-to-pod-etc-hosts-with-host-aliases