How to run `docker exec -it <container_name> bash -c "some commands"` using golang sdk

Question

I'm using docker's sdk in golang to execute a docker exec command.

func (dn *dockerNode) execCommand(ctx context.Context, cmd []string) (*execResult, error) {
    execId, err := dn.cl.ContainerExecCreate(ctx, dn.contId, types.ExecConfig{
        AttachStderr: true,
        AttachStdout: true,
        Tty:          true,
        Cmd:          cmd,
    })

    if err != nil {
        return nil, fmt.Errorf(
            "cannot create command \"%s\":\n %v",
            strings.Join(cmd, " "),
            err,
        )
    }

    res, err := dn.InspectExecResp(ctx, execId.ID)
    if err != nil {
        return nil, fmt.Errorf(
            "cannot execute command \"%s\":\n %v",
            strings.Join(cmd[:], " "),
            err,
        )
    }

    if res.exitCode != 0 {
        return &res, fmt.Errorf(
            "command \"%s\" exit with code %d:\n %+v",
            strings.Join(cmd[:], " "),
            res.exitCode,
            res)
    }

    return &res, nil
}

This dn.execCommand works fine just for some vanilla docker exec foo bar format command, but now I'd like to use it to run something equivalent to docker exec bash -c "cd mydir && ./my_shell.sh". This is because the cd command only works with docker exec bash -c. I tried passing this with

    res, err = dn.execCommand(
        ctx,
        []string{
            "bash",
            "-c",
            "\"cd mydir && ./my_shell.sh\"",
        },
    )

But it gave me command "bash -c "cd mydir && ./my_shell.sh" " exit with code 127

I wonder how to modify the original function to make it support the docker exec bash -c use case.

David Maze · Accepted Answer · 2021-12-20 12:21:40Z

1

Your last command has an extra layer of quotes.

command := []string{
        "bash",
        "-c",
        "cd mydir && ./my_shell.sh",
//      ^^no quotes inside string^^
}

If you were to run a similar command on the host

bash -c "cd mydir && ./my_shell.sh"

the shell would take the double-quoted string and turn it into a single word, and then discard the quotes. You can see this in part by putting the word echo in front of the command line, so the processed command gets printed out rather than executed; the double-quotes will be gone. What you're running is more similar to

bash -c '"cd mydir && ./my_shell.sh"'

Also note that the "github.com/docker/docker/api/types".ExecConfig structure contains a WorkingDir field, so you might be able to avoid this wrapper. Scripting docker exec also frequently isn't the best design, since you need unlimited administrator-level permissions over the host to use it, and since a container typically only runs one process.

answered Dec 20, 2021 at 12:21

David Maze

165k47 gold badges262 silver badges302 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

IsaIkari Over a year ago

Thanks! the WorkingDir field works perfectly for me!!

Collectives™ on Stack Overflow

How to run `docker exec -it <container_name> bash -c "some commands"` using golang sdk

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related