How to execute multiple commands in a Pod's container with client-go?

Question

So I've tried to execute a chain ie multiple commands on a Pod's container using client-go , and it seems to only work for some commands like ls .

Here is what I've tried:

    req := client.CoreV1().RESTClient().Post().Resource("pods").Name(pod.Name).Namespace(pod.ObjectMeta.Namespace).SubResource("exec") // .Param("container", containerName)
    scheme := runtime.NewScheme()
    if err := _v1.AddToScheme(scheme); err != nil {
        panic(err.Error())
    }
    parameterCodec := runtime.NewParameterCodec(scheme)
    req.VersionedParams(&_v1.PodExecOptions{
        Stdin:     false,
        Stdout:    true,
        Stderr:    true,
        TTY:       false,
        Container: containerName,
        Command:   strings.Fields("/bin/sh -c " + command),
    }, parameterCodec)
    exec, err := remotecommand.NewSPDYExecutor(restConfig, "POST", req.URL())
    if err != nil {
        panic(err.Error())
    }
    var stdout, stderr bytes.Buffer
    err = exec.Stream(remotecommand.StreamOptions{
        Stdin:  nil,
        Stdout: &stdout,
        Stderr: &stderr,
        Tty:    false,
    })
    if err != nil {
        panic(err.Error())
    }
log.Printf("Output from pod: %v", stdout.String())
log.Printf("Error from pod: %v", stderr.String())

When the command variable is just a simple ls -l , I get the desired output. But when I try to do something like 'ls -l && echo hello' it produces an error command terminated with exit code 2 . It doesn't output anything if I only put echo hello . However, it does produce the desired output hello if I remove the Bourne Shell prefix /bin/sh -c and the Command attribute equals to string.Fields("echo hello") , but this approach doesn't let me chain commands.

All in all, what I am trying to do is to execute a chain of commands on a Pod's container.

Answer 1

The corev1.PodExecOptions.Command accept value of []string type.

req.VersionedParams(&_v1.PodExecOptions{
  Stdin:     false,
  Stdout:    true,
  Stderr:    true,
  TTY:       false,
  Container: containerName,
  Command:   cmds,
}, parameterCodec)

where, cmds can be:

cmds := []string{
    "sh",
    "-c",
    "echo $HOME; ls -l && echo hello",
    }

Output:

/root
total 68
drwxr-xr-x   2 root root 4096 Feb 24 00:00 bin
drwxr-xr-x   2 root root 4096 Feb  1 17:09 boot
drwxr-xr-x   2 root root 4096 Feb 24 00:00 mnt
drwxr-xr-x   2 root root 4096 Feb 24 00:00 opt
dr-xr-xr-x 396 root root    0 Mar 19 11:47 proc
drwx------   2 root root 4096 Feb 24 00:00 root
.
.
hello

Explanation: Tim's answer

command: ["/bin/sh","-c"]
args: ["command one; command two && command three"]

The command ["/bin/sh", "-c"] says "run a shell, and execute the following instructions" . The args are then passed as commands to the shell. In shell scripting a semicolon separates commands, and && conditionally runs the following command if the first succeed. In the above example, it always runs command one followed by command two , and only runs command three if command two succeeded.

NB: For bash, it will be similar to something like below:

cmds := []string{
     "bash",
     "-c",
     `export MYSQL_PWD=${MYSQL_ROOT_PASSWORD}
mysql -h localhost -nsLNE -e "select 1;" 2>/dev/null | grep -v "*"`,
                    },