Method command

src/cmd/linuxkit/pkglib/dockerimpl.go:101–137

(stdin io.Reader, stdout, stderr io.Writer, args ...string)

}

func (dr *dockerRunnerImpl) command(stdin io.Reader, stdout, stderr io.Writer, args ...string) error {
	cmd := exec.Command("docker", args...)
	if stdin == nil {
		stdin = os.Stdin
	}
	if stdout == nil {
		stdout = os.Stdout
	}
	if stderr == nil {
		if runtime.GOOS != "windows" {
			stderr = os.Stderr
		} else {
			// On Windows directly setting stderr to os.Stderr results in the output being written to stdout,
			// corrupting the image tar. Adding an explicit indirection via a pipe works around the issue.
			r, w := io.Pipe()
			stderr = w
			go func() {
				_, _ = io.Copy(os.Stderr, r)
			}()
		}
	}
	cmd.Stdout = stdout
	cmd.Stderr = stderr
	cmd.Stdin = stdin
	cmd.Env = os.Environ()

	log.Debugf("Executing: %v", cmd.Args)

	err := cmd.Run()
	if err != nil {
		if isExecErrNotFound(err) {
			return fmt.Errorf("linuxkit pkg requires docker to be installed")
		}
		return err
	}
	return nil
}

// versionCheck returns the client version and server version, and compares them both
// against the minimum required version.