如何使用 go-client 在 k8s 中访问我的 pod

Question

I am using go-client to access k8s resources in my environment. There are APIs to get/list pods, namespaces, etc.

How do I access the pod that I am currently running on?

Answer 1

You can Expose Pod Information to Containers Through Environment Variables using pod fields :

apiVersion: v1
kind: Pod
metadata:
  name: dapi-envars-fieldref
spec:
  containers:
    - name: test-container
      ...
      ...
      env:
        - name: MY_NODE_NAME
          valueFrom:
            fieldRef:
              fieldPath: spec.nodeName
        - name: MY_POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: MY_POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: MY_POD_IP
          valueFrom:
            fieldRef:
              fieldPath: status.podIP
        - name: MY_POD_SERVICE_ACCOUNT
          valueFrom:
            fieldRef:
              fieldPath: spec.serviceAccountName
  restartPolicy: Never

then simply look up these env vars in your Go code:

log.Printf("MY_POD_NAME: %q", os.Getenv("MY_POD_NAME"))

Answer 2

The Kube.netes client-go supplies API to access pods, and the CoreV1 package gives an API to get All Pods see the documentation https://pkg.go.dev/k8s.io/client-go/kube.netes/typed/core/v1#CoreV1Client.Pods

You can easily filter or fetch Pods by Namespace, Label or Query,

See a sample code to get all pods in Namespace.

  config, err := clientcmd.BuildConfigFromFlags("", "PATH to cluster config yaml")
  clientset, err := kubernetes.NewForConfig(config)
  if err != nil {
     panic(err.Error())
  }
  // Get all pods in namespace
  pods, err := clientset.CoreV1().Pods("NANESPACE").List(context.TODO(), 
  metav1.ListOptions{})
  if err != nil {
          panic(err.Error())
  }

See the Sample code for getting pods using a label:

 labal := fmt.Sprintf("LABLE-NAME=%s", "SOME LABEL VALUE")
    ap1 := sm.clientset.CoreV1()
    pods, _ := ap1.Pods(namespace).List(context.Background(), 
         metav1.ListOptions{LabelSelector: labal})
    pods_num := len(pods.Items)
    fmt.Printf("Found the following number of Pods: %d\n", pods_num)
    for i, pod := range pods.Items {
        fmt.Printf("[%2d] %s, Phase: %s, Created: %s, HostIP: %s\n", i, 
              pod.GetName(), string(pod.Status.Phase), 
              pod.GetCreationTimestamp(), 
              string(pod.Status.HostIP))
     }