func main()

in google_metadata_script_runner/main.go [419:494]
60 lines of code
13 McCabe index (conditional complexity)

func main() {
	ctx := context.Background()

	opts := logger.LogOpts{LoggerName: programName}

	if runtime.GOOS == "windows" {
		opts.Writers = []io.Writer{&utils.SerialPort{Port: "COM1"}, os.Stdout}
		opts.FormatFunction = logFormatWindows
	} else {
		opts.Writers = []io.Writer{os.Stdout}
		opts.FormatFunction = func(e logger.LogEntry) string { return e.Message }
		// Local logging is syslog; we will just use stdout in Linux.
		opts.DisableLocalLogging = true
	}

	var err error
	if err := cfg.Load(nil); err != nil {
		fmt.Fprintf(os.Stderr, "Failed to load instance configuration: %+v", err)
		os.Exit(1)
	}

	if !cfg.Get().Core.CloudLoggingEnabled {
		opts.DisableCloudLogging = true
	}

	// The keys to check vary based on the argument and the OS. Also functions to validate arguments.
	wantedKeys, err := getWantedKeys(os.Args, runtime.GOOS)
	if err != nil {
		fmt.Printf("%s\n", err.Error())
		os.Exit(2)
	}

	projectID, err := getMetadataKey(ctx, "/project/project-id")
	if err == nil {
		opts.ProjectName = projectID
	}
	createdBy, err := getMetadataKey(ctx, "/instance/attributes/created-by")
	if err == nil {
		opts.MIG = createdBy
	}

	if err := logger.Init(ctx, opts); err != nil {
		fmt.Printf("Error initializing logger: %+v", err)
		os.Exit(1)
	}

	// Try flushing logs before exiting, if not flushed logs could go missing.
	defer logger.Close()

	logger.Infof("Starting %s scripts (version %s).", os.Args[1], version)

	scripts, err := getExistingKeys(ctx, wantedKeys)
	if err != nil {
		logger.Fatalf(err.Error())
	}

	if len(scripts) == 0 {
		logger.Infof("No %s scripts to run.", os.Args[1])
		return
	}

	for _, wantedKey := range wantedKeys {
		value, ok := scripts[wantedKey]
		if !ok {
			continue
		}
		logger.Infof("Found %s in metadata.", wantedKey)
		if err := setupAndRunScript(ctx, wantedKey, value); err != nil {
			logger.Warningf("Script %q failed with error: %v", wantedKey, err)
			continue
		}
		logger.Infof("%s exit status 0", wantedKey)
	}

	logger.Infof("Finished running %s scripts.", os.Args[1])
}