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