Examples

The simplest example

The following example creates a new pod based on the official Ubuntu image, then simply prints a message.

Note: Because of a known temporary limitation, if the execution time of the command started inside the pod is too small, the logs will not be visible when executing, but have to be gathered using kubectl. Because of this reason, in this example there is a sleep command as well. This does not affect functionality, the command can be executed without the additional sleep statement, and this will be improved in the future.

package main

import (
	"log"
	"os"

	kube "github.com/engineerd/kube-exec"
)

func main() {

	cfg := kube.Config{
		Kubeconfig: os.Getenv("KUBECONFIG"),
		Image:      "ubuntu",
		Name:       "kube-example",
		Namespace:  "default",
	}

	// also sleeping for a couple of seconds
	// if the pod completes too fast, we don't have time to attach to it

	cmd := kube.Command(cfg, "/bin/sh", "-c", "sleep 2; echo Running from Kubernetes pod;")
	cmd.Stdout = os.Stdout

	err := cmd.Run()
	if err != nil {
		log.Fatalf("error: %v", err)
	}

}

Passing stdin to the pod

Because this package follows the implementation of os/exec, you can also pass a pipe to the started pod and use it as standard input, as well as standard output, and standard error.

func main() {

	cfg := kube.Config{
		Kubeconfig: os.Getenv("KUBECONFIG"),
		Image:      "ubuntu",
		Name:       "kube-attach",
		Namespace:  "default",
	}

	cmd := kube.Command(cfg, "/bin/sh", "-c", "while true; read test; do echo You said: $test; sleep .5; done")

	w, err := cmd.StdinPipe()
	if err != nil {
		log.Fatalf("cannot get pipe to stdin: %v", err)
	}

	// write in cmd.Stdin
	go func() {
		defer w.Close()
		_, err = io.Copy(w, os.Stdin)
		if err != nil {
			log.Fatalf("cannot copy from stdin: %v", err)
		}
	}()

	cmd.Stdout = os.Stdout

	err = cmd.Run()
	if err != nil {
		log.Fatalf("error: %v", err)
	}

}

Passing secrets to the pod

If you need secret values to use inside your pod, Kubernetes secrets are available as environment variables.

func main() {
	cfg := kube.Config{
		Kubeconfig: os.Getenv("KUBECONFIG"),
		Image:      "ubuntu",
		Name:       "secret",
		Namespace:  "default",

		Secrets: []kube.Secret{
			{
				EnvVarName: "SUPERPRIVATESECRET",
				SecretName: "k8s-secret",
				SecretKey:  "password",
			},
		},
	}

	cmd := kube.Command(cfg, "/bin/sh", "-c", "sleep 2; echo Your private secret: $SUPERPRIVATESECRET;")
	cmd.Stdout = os.Stdout

	err := cmd.Run()
	if err != nil {
		log.Fatalf("error: %v", err)
	}

}