scrape/manager.go
func (m *Manager) ApplyConfig(cfg *config.Config) error {
	m.mtxScrape.Lock()
	defer m.mtxScrape.Unlock()

	c := make(map[string]*config.ScrapeConfig)
	for _, scfg := range cfg.ScrapeConfigs {
		c[scfg.JobName] = scfg
	}
	m.scrapeConfigs = c

	if err := m.setJitterSeed(cfg.GlobalConfig.ExternalLabels); err != nil {
		return err
	}

	// Cleanup and reload pool if the configuration has changed.
	var failed bool
	for name, sp := range m.scrapePools {
		if cfg, ok := m.scrapeConfigs[name]; !ok {
			sp.stop()
			delete(m.scrapePools, name)
		} else if !reflect.DeepEqual(sp.config, cfg) {
			err := sp.reload(cfg)
			if err != nil {
				level.Error(m.logger).Log("msg", "error reloading scrape pool", "err", err, "scrape_pool", name)
				failed = true
			}
		}
	}

	if failed {
		return errors.New("failed to apply the new configuration")
	}
	return nil
}
func (m *Manager) ApplyConfig(cfg *config.Config) error {
	m.mtxScrape.Lock()
	defer m.mtxScrape.Unlock()

	c := make(map[string]*config.ScrapeConfig)
	for _, scfg := range cfg.ScrapeConfigs {
		c[scfg.JobName] = scfg
	}
	m.scrapeConfigs = c

	if err := m.setJitterSeed(cfg.GlobalConfig.ExternalLabels); err != nil {
		return err
	}

	// Cleanup and reload pool if the configuration has changed.
	var failed bool
	for name, sp := range m.scrapePools {
		if cfg, ok := m.scrapeConfigs[name]; !ok {
			sp.stop()
			delete(m.scrapePools, name)
		} else if !reflect.DeepEqual(sp.config, cfg) {
			err := sp.reload(cfg)
			if err != nil {
				level.Error(m.logger).Log("msg", "error reloading scrape pool", "err", err, "scrape_pool", name)
				failed = true
			}
		}
	}

	if failed {
		return errors.New("failed to apply the new configuration")
	}
	return nil
}
// ApplyConfig resets the manager's target providers and job configurations as defined by the new cfg.