Application Scenarios

If DNS or other related settings are inappropriate, you can use hostAliases to overwrite the resolution of the hostname at the pod level when adding entries to the /etc/hosts file of the pod.

Procedure

Use kubectl to connect to the cluster.

Create the hostaliases-pod.yaml file.

vi hostaliases-pod.yaml

The field in bold in the YAML file indicates the image name and tag. You can replace the example value as required.

apiVersion: v1
kind: Pod
metadata:
  name: hostaliases-pod
spec:
  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: tomcat:9-jre11-slim
      lifecycle:
        postStart:
          exec:
            command:
              - cat
              - /etc/hosts
  imagePullSecrets:
    - name: default-secret

**Table 1** pod field description
Parameter	Mandatory	Description
apiVersion	Yes	API version number
kind	Yes	Type of the object to be created
metadata	Yes	Metadata definition of a resource object
name	Yes	Name of a pod
spec	Yes	Detailed description of the pod. For details, see Table 2.

**Table 2** spec field description
Parameter	Mandatory	Description
hostAliases	Yes	Host alias
containers	Yes	For details, see Table 3.

**Table 3** containers field description
Parameter	Mandatory	Description
name	Yes	Container name
image	Yes	Container image name
lifecycle	No	Lifecycle

Create a pod.
kubectl create -f hostaliases-pod.yaml

If information similar to the following is displayed, the pod is created.
```
pod/hostaliases-pod created
```

Query the pod status.

kubectl get pod hostaliases-pod

If the pod is in the Running state, the pod is successfully created.

NAME                  READY          STATUS       RESTARTS      AGE
hostaliases-pod       1/1            Running      0             16m

Check whether the hostAliases functions properly.
docker ps |grep hostaliases-pod

docker exec -ti Container ID /bin/sh

Configuring the /etc/hosts File of a Pod Using hostAliases

Application Scenarios

Procedure