Function selectEventProcessor

cmd/compose/compose.go:647–681

selectEventProcessor picks the EventProcessor for Compose progress rendering. In auto mode we probe Err() (not Out()) because the renderer writes to stderr; probing stdout would force plain mode whenever stdout is redirected (e.g. `docker compose up | tee log`) while stderr is still a terminal.

(dockerCli command.Cli, progress, ansi string, detached bool)

// probing stdout would force plain mode whenever stdout is redirected (e.g.
// `docker compose up | tee log`) while stderr is still a terminal.
func selectEventProcessor(dockerCli command.Cli, progress, ansi string, detached bool) (api.EventProcessor, error) {
	switch progress {
	case "", display.ModeAuto:
		switch {
		case ansi == "never":
			display.Mode = display.ModePlain
			return display.Plain(dockerCli.Err()), nil
		case dockerCli.Err().IsTerminal():
			return display.Full(dockerCli.Err(), stdinfo(dockerCli), detached), nil
		default:
			return display.Plain(dockerCli.Err()), nil
		}
	case display.ModeTTY:
		if ansi == "never" {
			return nil, fmt.Errorf("can't use --progress tty while ANSI support is disabled")
		}
		display.Mode = display.ModeTTY
		return display.Full(dockerCli.Err(), stdinfo(dockerCli), detached), nil
	case display.ModePlain:
		if ansi == "always" {
			return nil, fmt.Errorf("can't use --progress plain while ANSI support is forced")
		}
		display.Mode = display.ModePlain
		return display.Plain(dockerCli.Err()), nil
	case display.ModeQuiet, "none":
		display.Mode = display.ModeQuiet
		return display.Quiet(), nil
	case display.ModeJSON:
		display.Mode = display.ModeJSON
		logrus.SetFormatter(&logrus.JSONFormatter{})
		return display.JSON(dockerCli.Err()), nil
	default:
		return nil, fmt.Errorf("unsupported --progress value %q", progress)
	}
}

func setEnvWithDotEnv(opts ProjectOptions, dockerCli command.Cli) error {
	// Check if we're using a remote config (OCI or Git)