Home  >  Article  >  Backend Development  >  How to copy local files to pod container in minikube cluster using Go client?

How to copy local files to pod container in minikube cluster using Go client?

PHPz
PHPzforward
2024-02-06 08:06:141056browse

如何使用 Go 客户端将本地文件复制到 minikube 集群中的 pod 容器?

Question content

My query is almost the same as the title, I have a local file file.txt and I want to copy it To container container1 in pod1.

If I use kubectl to do this, the appropriate command is:

kubectl cp file.txt pod1:file.txt -c container1

But, how to use kubectl's go client to achieve it?

I tried two methods but neither worked:

import (
    "fmt"
    "context"
    "log"
    "os"
    "path/filepath"

    g "github.com/sdslabs/katana/configs"
    v1 "k8s.io/api/core/v1"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/apimachinery/pkg/labels"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/rest"
    "k8s.io/client-go/tools/clientcmd"
    //"k8s.io/kubectl/pkg/cmd/exec"
)

func copyintopod(namespace string, podname string, containername string, srcpath string, dstpath string) {
    // create a kubernetes client
    config, err := getkubeconfig()
    if err != nil {
        log.fatal(err)
    }

    client, err := kubernetes.newforconfig(config)
    if err != nil {
        log.fatal(err)
    }

    // build the command to execute
    cmd := []string{"cp", srcpath, dstpath}

    // use the podexecoptions struct to specify the options for the exec request
    options := v1.podexecoptions{
        container: containername,
        command:   cmd,
        stdin:     false,
        stdout:    true,
        stderr:    true,
        tty:       false,
    }
    log.println("options set!")

    // use the corev1api.exec method to execute the command inside the container
    req := client.corev1().restclient().post().
        namespace(namespace).
        name(podname).
        resource("pods").
        subresource("exec").
        versionedparams(&options, metav1.parametercodec)
    log.println("request generated")
    
    exec, err := req.stream(context.todo())
    if err != nil {
        log.fatal(err)
    }
    defer exec.close()

    // read the response from the exec command
    var result []byte
    if _, err := exec.read(result); err != nil {
        log.fatal(err)
    }

    fmt.println("file copied successfully!")
}

This gave me the error message:

no type is already registered for v1.podexecoptions type in scheme "pkg/runtime/scheme.go:100"

I couldn't figure it out, so I tried another approach:

type PodExec struct {
    RestConfig *rest.Config
    *kubernetes.Clientset
}

func NewPodExec(config *rest.Config, clientset *kubernetes.Clientset) *PodExec {
    config.APIPath = "/api" // Make sure we target /api and not just /
    config.GroupVersion = &schema.GroupVersion{Version: "v1"} // this targets the core api groups so the url path will be /api/v1
    config.NegotiatedSerializer = serializer.WithoutConversionCodecFactory{CodecFactory: scheme.Codecs}
    return &PodExec{
      RestConfig: config,
      Clientset:  clientset,
    }  
}

func (p *PodExec) PodCopyFile(src string, dst string, containername string, podNamespace string) (*bytes.Buffer, *bytes.Buffer, *bytes.Buffer, error) {
    ioStreams, in, out, errOut := genericclioptions.NewTestIOStreams()
    copyOptions := cp.NewCopyOptions(ioStreams)
    copyOptions.Clientset = p.Clientset
    copyOptions.ClientConfig = p.RestConfig
    copyOptions.Container = containername
    copyOptions.Namespace = podNamespace
    err := copyOptions.Run()
    if err != nil {
        return nil, nil, nil, fmt.Errorf("could not run copy operation: %v", err)
    }
    return in, out, errOut, nil
}

However, the

copyoptions.run() command has some issues, it tries to find o.args[0] and o.args[0] within copyoptions, but o is not imported, so it cannot be imported for modification.

Context: https://pkg.go.dev/k8s.io/kubectl/pkg/cmd/cp#copyoptions.run

So, now I'm really lost and confused. Any help would be greatly appreciated. Thanks.

Edit: I did think of a possible way, we could just call

cmd.exec() and run the kubectl cp command directly, but it seems a bit old-fashioned to me Not sure if it works, any ideas?


Correct Answer


This is how I finally managed to do this:

package main

import (
    "context"
    "fmt"
    "os"
    "path/filepath"

    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/kubernetes/scheme"
    corev1 "k8s.io/api/core/v1"
    "k8s.io/client-go/tools/clientcmd"
    "k8s.io/client-go/util/homedir"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/tools/remotecommand"
)

func CopyIntoPod(podName string, namespace string, containerName string, srcPath string, dstPath string) {
    // Get the default kubeconfig file
    kubeConfig := filepath.Join(homedir.HomeDir(), ".kube", "config")

    // Create a config object using the kubeconfig file
    config, err := clientcmd.BuildConfigFromFlags("", kubeConfig)
    if err != nil {
        fmt.Printf("Error creating config: %s\n", err)
        return
    }

    // Create a Kubernetes client
    client, err := kubernetes.NewForConfig(config)
    if err != nil {
        fmt.Printf("Error creating client: %s\n", err)
        return
    }

    // Open the file to copy
    localFile, err := os.Open(srcPath)
    if err != nil {
        fmt.Printf("Error opening local file: %s\n", err)
        return
    }
    defer localFile.Close()

    pod, err := client.CoreV1().Pods(namespace).Get(context.TODO(), podName, metav1.GetOptions{})
    if err != nil {
        fmt.Printf("Error getting pod: %s\n", err)
        return
    }

    // Find the container in the pod
    var container *corev1.Container
    for _, c := range pod.Spec.Containers {
        if c.Name == containerName {
            container = &c
            break
        }
    }

    if container == nil {
        fmt.Printf("Container not found in pod\n")
        return
    }

    // Create a stream to the container
    req := client.CoreV1().RESTClient().Post().
        Resource("pods").
        Name(podName).
        Namespace(namespace).
        SubResource("exec").
        Param("container", containerName)   

    req.VersionedParams(&corev1.PodExecOptions{
        Container: containerName,
        Command:   []string{"bash", "-c", "cat > " + dstPath},
        Stdin:     true,
        Stdout:    true,
        Stderr:    true,
    }, scheme.ParameterCodec)

    exec, err := remotecommand.NewSPDYExecutor(config, "POST", req.URL())
    if err != nil {
        fmt.Printf("Error creating executor: %s\n", err)
        return
    }

    // Create a stream to the container
    err = exec.StreamWithContext(context.TODO(), remotecommand.StreamOptions{
        Stdin:  localFile,
        Stdout: os.Stdout,
        Stderr: os.Stderr,
        Tty:    false,
    })
    if err != nil {
        fmt.Printf("Error streaming: %s\n", err)
        return
    }

    fmt.Println("File copied successfully")
}

The above is the detailed content of How to copy local files to pod container in minikube cluster using Go client?. For more information, please follow other related articles on the PHP Chinese website!

Statement:
This article is reproduced at:stackoverflow.com. If there is any infringement, please contact admin@php.cn delete