using nerdctl in Go exec.Command is unresponsive

[tianyax]

Description

When I call nerdctl in the go program to create a container, there is no response, but the container has been pulled up normally, and the nerdctl run process in the virtual machine has been executed.

func RunCmdAndWait(name string, args ...string) (string, error) {
    cmd := exec.Command(name, args...)
    stdout, _ := cmd.StdoutPipe()
    stderr, _ := cmd.StderrPipe()
    if err := cmd.Start(); err != nil {
        return "", err
    }
    resp, err := io.ReadAll(stdout)
    if err != nil {
        return "", err
    }
    errB, err := io.ReadAll(stderr)
    if err != nil {
        return "", nil
    }
    err = cmd.Wait()
    ...
}

func main() {
    resp, err := RunCmdAndWait("nerdctl", "run", "-d", "--name", "redis", "redis")
    ...
}

This is only a problem if I need to pull the image.

System information:

os: macOS
lima version: 0.15.0
runtime: containerd

[AkihiroSuda]

This is expected, as io.ReadAlll(stdout) stucks until stdout is closed

You may just want this:

var stdout bytes.Buffer
cmd.Stdout = &stdout

[tianyax]

Yes, there is no problem with cmd.Stdout = &stdout, but I think this may be bypassing the problem? 😅 cmd.Stdout = &stdout spawns a goroutine and it will live until the program exits, also, I would like to ask why stdout is not closed, the nerdctl program in lima has already exited. 😄️