reload config file (prometheus.yml)

main.go

func reloadConfig(filename string, logger log.Logger, rls ...func(*config.Config) error) (err error) {
	level.Info(logger).Log("msg", "Loading configuration file", "filename", filename)

	defer func() {
		if err == nil {
			configSuccess.Set(1)
			configSuccessTime.SetToCurrentTime()
		} else {
			configSuccess.Set(0)
		}
	}()

	conf, err := config.LoadFile(filename)
	if err != nil {
		return fmt.Errorf("couldn't load configuration (--config.file=%s): %v", filename, err)
	}

	failed := false
	for _, rl := range rls {
		if err := rl(conf); err != nil {
			level.Error(logger).Log("msg", "Failed to apply configuration", "err", err)
			failed = true
		}
	}
	if failed {
		return fmt.Errorf("one or more errors occurred while applying the new configuration (--config.file=%s)", filename)
	}
	return nil
}