kubernetes dev client-go 进入pod执行命令

---

文章目录

---

1. 创建pod

deploy-pod.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
  labels:
    app: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80

$ kubectl apply -f deploy-pod.yaml

$ kubectl get deployment
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
myapp   2/2     2            2           3h45m

$ kubectl get pods
NAME                    READY   STATUS    RESTARTS   AGE
myapp-d46f5678b-m98p2   1/1     Running   0          3h45m
myapp-d46f5678b-x9b6g   1/1     Running   0          3h45m

2. go执行进入单个pod执行命令

go.mod

module client

go 1.13

require (
  github.com/evanphx/json-patch v4.9.0+incompatible // indirect
  github.com/fsnotify/fsnotify v1.4.9 // indirect
  github.com/golang/groupcache v0.0.0-20191227052852-215e87163ea7 // indirect
  github.com/golang/protobuf v1.4.2 // indirect
  github.com/googleapis/gnostic v0.4.0 // indirect
  github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79 // indirect
  github.com/imdario/mergo v0.3.11 // indirect
  github.com/json-iterator/go v1.1.10 // indirect
  github.com/pkg/errors v0.9.1 // indirect
  golang.org/x/net v0.0.0-20200707034311-ab3426394381 // indirect
  golang.org/x/sys v0.0.0-20200622214017-ed371f2e16b4 // indirect
  golang.org/x/text v0.3.3 // indirect
  golang.org/x/time v0.0.0-20200630173020-3af7569d3a1e // indirect
  google.golang.org/protobuf v1.24.0 // indirect
  k8s.io/apimachinery v0.17.0
  k8s.io/client-go v0.17.0
  k8s.io/gengo v0.0.0-20200413195148-3a45101e95ac // indirect
  k8s.io/klog/v2 v2.2.0 // indirect
  k8s.io/utils v0.0.0-20201110183641-67b214c5f920 // indirect
  sigs.k8s.io/structured-merge-diff/v4 v4.0.1 // indirect
)

execpod.go

package main

import (
  "flag"
  "fmt"
  "io"
  "os"
  "path/filepath"

  "golang.org/x/crypto/ssh/terminal"
  corev1 "k8s.io/api/core/v1"
  "k8s.io/client-go/kubernetes"
  "k8s.io/client-go/kubernetes/scheme"
  "k8s.io/client-go/tools/clientcmd"
  "k8s.io/client-go/tools/remotecommand"
  "k8s.io/client-go/util/homedir"
)

func main() {
     var kubeconfig *string
     if home := homedir.HomeDir(); home != "" {
            kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")} else {
     kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
     }
     flag.Parse()
     
     config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
     if err != nil {
        panic(err)
     }
     clientset, err := kubernetes.NewForConfig(config)
     if err != nil {
        panic(err)
     }

     req := clientset.CoreV1().RESTClient().Post().
         Resource("pods").
         Name("myapp-d46f5678b-m98p2").
         Namespace("default").
         SubResource("exec").
         VersionedParams(&corev1.PodExecOptions{
             Command: []string{"echo", "hello world"},
             Stdin:   true,
             Stdout:  true,
             Stderr:  true,
             TTY:     false,
         }, scheme.ParameterCodec)
     exec, err := remotecommand.NewSPDYExecutor(config, "POST", req.URL())

     if !terminal.IsTerminal(0) || !terminal.IsTerminal(1) {
        fmt.Errorf("stdin/stdout should be terminal")
     }
     
     oldState, err := terminal.MakeRaw(0)
     if err != nil {
        fmt.Println(err)
     }
     
     defer terminal.Restore(0, oldState)
 
     screen := struct {
           io.Reader
           io.Writer
     }{os.Stdin, os.Stdout}
     
     if err = exec.Stream(remotecommand.StreamOptions{
        Stdin: screen,
        Stdout: screen,
        Stderr: screen,
        Tty:    false,
     }); err != nil {
        fmt.Print(err)
     }
}

执行测试:

$ go run execpod.go 
hello world

3. go执行进入某个命名空间的多个pod执行命令

go.mod

module client

go 1.13

require (
  github.com/evanphx/json-patch v4.9.0+incompatible // indirect
  github.com/fsnotify/fsnotify v1.4.9 // indirect
  github.com/golang/groupcache v0.0.0-20191227052852-215e87163ea7 // indirect
  github.com/golang/protobuf v1.4.2 // indirect
  github.com/googleapis/gnostic v0.4.0 // indirect
  github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79 // indirect
  github.com/imdario/mergo v0.3.11 // indirect
  github.com/json-iterator/go v1.1.10 // indirect
  github.com/pkg/errors v0.9.1 // indirect
  golang.org/x/net v0.0.0-20200707034311-ab3426394381 // indirect
  golang.org/x/sys v0.0.0-20200622214017-ed371f2e16b4 // indirect
  golang.org/x/text v0.3.3 // indirect
  golang.org/x/time v0.0.0-20200630173020-3af7569d3a1e // indirect
  google.golang.org/protobuf v1.24.0 // indirect
  k8s.io/apimachinery v0.17.0
  k8s.io/client-go v0.17.0
  k8s.io/gengo v0.0.0-20200413195148-3a45101e95ac // indirect
  k8s.io/klog/v2 v2.2.0 // indirect
  k8s.io/utils v0.0.0-20201110183641-67b214c5f920 // indirect
  sigs.k8s.io/structured-merge-diff/v4 v4.0.1 // indirect
)

package main
import (
  "bufio"
  "fmt"
  "io"

  "github.com/spf13/pflag"
  v1 "k8s.io/api/core/v1"
  "k8s.io/client-go/kubernetes"
  "k8s.io/client-go/kubernetes/scheme"
  restclient "k8s.io/client-go/rest"
  "k8s.io/client-go/tools/clientcmd"
  "k8s.io/client-go/tools/remotecommand"
        metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)


type App struct {
  Config    *restclient.Config
  Namespace string
  PodName   string
}

func NewApp(namespace string, podName string) *App {
  config := LoadKubernetesConfig()
  return &App{Config: config, Namespace: namespace, PodName: podName}
}


func LoadKubernetesConfig() *restclient.Config {
  kubeconfig := pflag.Lookup("kubefile").Value.String()
  // uses the current context in kubeconfig
  config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
  if err != nil {
    panic(err.Error())
  }
  return config
}

func ExecCommandInPodContainer(config *restclient.Config, namespace string, podName string, containerName string,
  command string) (string, error) {
  client, err := kubernetes.NewForConfig(config)

  reader, writer := io.Pipe()
  var cmdOutput string

  go func() {
    scanner := bufio.NewScanner(reader)
    for scanner.Scan() {
      line := scanner.Text()
      cmdOutput += fmt.Sprintln(line)
    }
  }()

  stdin := reader
  stdout := writer
  stderr := writer
  tty := false

  cmd := []string{
    "bash",
    "-c",
    command,
  }

  req := client.CoreV1().RESTClient().Post().Resource("pods").Name(podName).
    Namespace(namespace).SubResource("exec")

  option := &v1.PodExecOptions{
    Command:   cmd,
    Container: containerName,
    Stdin:     stdin != nil,
    Stdout:    stdout != nil,
    Stderr:    stderr != nil,
    TTY:       tty,
  }

  req.VersionedParams(
    option,
    scheme.ParameterCodec,
  )
  exec, err := remotecommand.NewSPDYExecutor(config, "POST", req.URL())
  if err != nil {
    return "", err
  }
  err = exec.Stream(remotecommand.StreamOptions{
    Stdin:  stdin,
    Stdout: stdout,
    Stderr: stderr,
    Tty:    tty,
  })

  if err != nil {
    return "", err
  }

  return cmdOutput, nil
}

func (orch *App) GetClusterInfo() (string, error) {
  // check clusters info
  result, err := ExecCommandInPodContainer(orch.Config, orch.Namespace, orch.PodName, "nginx", "echo `date +%Y%m%d-%H:%M` hello wold")
  if err != nil {
    fmt.Println("Error occoured" + err.Error())
  }
  return result, nil
}


func main() {
  pflag.String("kubefile", "/root/.kube/config", "Kube file to load")
        pflag.String("namespace", "default", "App Namespace")
        pflag.Parse()
        appNamespace := pflag.Lookup("namespace").Value.String()
        config := LoadKubernetesConfig()
  client, err := kubernetes.NewForConfig(config)
        if err != nil {
           fmt.Println(err.Error())
        }
        appPodList, err := client.CoreV1().Pods(appNamespace).List(metav1.ListOptions{})
        if err != nil {
           fmt.Println(err.Error())
        }

        for _, pod := range appPodList.Items {
            app := NewApp(pod.ObjectMeta.Namespace, pod.ObjectMeta.Name)
            result, err := app.GetClusterInfo()
            if err != nil {
    fmt.Println(err.Error())
      }
            fmt.Println(result)
        }
}

$ go run test1.go
20201216-10:13 hello wold

20201216-10:13 hello wold

参考链接：
​​​https://godoc.org/k8s.io/client-go/util/homedir​​​​https://godoc.org/k8s.io/client-go/tools/remotecommand​​

​