Prometheus源码分析(四)Prometheus启动过程

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Prometheus启动过程

启动入口源码

func Main() int {    if err := parse(os.Args[1:]); err != nil {        log.Error(err)        return 2    }    if cfg.printVersion {        fmt.Fprintln(os.Stdout, version.Print("prometheus"))        return 0    }    log.Infoln("Starting prometheus", version.Info())    log.Infoln("Build context", version.BuildContext())    var reloadables []Reloadable    var (        memStorage     = local.NewMemorySeriesStorage(&cfg.storage)        remoteStorage  = remote.New(&cfg.remote)        sampleAppender = storage.Fanout{memStorage}    )    if remoteStorage != nil {        sampleAppender = append(sampleAppender, remoteStorage)        reloadables = append(reloadables, remoteStorage)    }    var (        notifier      = notifier.New(&cfg.notifier)        targetManager = retrieval.NewTargetManager(sampleAppender)        queryEngine   = promql.NewEngine(memStorage, &cfg.queryEngine)    )    ruleManager := rules.NewManager(&rules.ManagerOptions{        SampleAppender: sampleAppender,        Notifier:       notifier,        QueryEngine:    queryEngine,        ExternalURL:    cfg.web.ExternalURL,    })    flags := map[string]string{}    cfg.fs.VisitAll(func(f *flag.Flag) {        flags[f.Name] = f.Value.String()    })    // 当前版本信息    version := &web.PrometheusVersion{        Version:   version.Version,        Revision:  version.Revision,        Branch:    version.Branch,        BuildUser: version.BuildUser,        BuildDate: version.BuildDate,        GoVersion: version.GoVersion,    }    webHandler := web.New(memStorage, queryEngine, targetManager, ruleManager, version, flags, &cfg.web)    reloadables = append(reloadables, targetManager, ruleManager, webHandler, notifier)    if !reloadConfig(cfg.configFile, reloadables...) {        return 1    }    // Wait for reload or termination signals. Start the handler for SIGHUP as    // early as possible, but ignore it until we are ready to handle reloading    // our config.    hup := make(chan os.Signal)    hupReady := make(chan bool)    signal.Notify(hup, syscall.SIGHUP)    go func() {        <-hupReady        for {            select {            case <-hup:            case <-webHandler.Reload():            }            reloadConfig(cfg.configFile, reloadables...)        }    }()    // Start all components. The order is NOT arbitrary.    if err := memStorage.Start(); err != nil {        log.Errorln("Error opening memory series storage:", err)        return 1    }    defer func() {        if err := memStorage.Stop(); err != nil {            log.Errorln("Error stopping storage:", err)        }    }()    if remoteStorage != nil {        prometheus.MustRegister(remoteStorage)        go remoteStorage.Run()        defer remoteStorage.Stop()    }    // The storage has to be fully initialized before registering.    prometheus.MustRegister(memStorage)    prometheus.MustRegister(notifier)    prometheus.MustRegister(configSuccess)    prometheus.MustRegister(configSuccessTime)    // The notifieris a dependency of the rule manager. It has to be    // started before and torn down afterwards.    go notifier.Run()    defer notifier.Stop()    go ruleManager.Run()    defer ruleManager.Stop()    go targetManager.Run()    defer targetManager.Stop()    // Shutting down the query engine before the rule manager will cause pending queries    // to be canceled and ensures a quick shutdown of the rule manager.    defer queryEngine.Stop()    go webHandler.Run()    // Wait for reload or termination signals.    close(hupReady) // Unblock SIGHUP handler.    term := make(chan os.Signal)    signal.Notify(term, os.Interrupt, syscall.SIGTERM)    select {    case <-term:        log.Warn("Received SIGTERM, exiting gracefully...")    case <-webHandler.Quit():        log.Warn("Received termination request via web service, exiting gracefully...")    case err := <-webHandler.ListenError():        log.Errorln("Error starting web server, exiting gracefully:", err)    }    log.Info("See you next time!")    return 0}// Reloadable things can change their internal state to match a new config// and handle failure gracefully.type Reloadable interface {    ApplyConfig(*config.Config) bool}// 配置加载处理func reloadConfig(filename string, rls ...Reloadable) (success bool) {    log.Infof("Loading configuration file %s", filename)    defer func() {        if success {            configSuccess.Set(1)            configSuccessTime.Set(float64(time.Now().Unix()))        } else {            configSuccess.Set(0)        }    }()    conf, err := config.LoadFile(filename)    if err != nil {        log.Errorf("Couldn't load configuration (-config.file=%s): %v", filename, err)        return false    }    success = true    for _, rl := range rls {        success = success && rl.ApplyConfig(conf)    }    return success}

• 2行：parse方法解析命令行参数
  
• 18~25行：根据所解析的命令行参数构造指标存储引擎（本地模式或者远程模式[opentsdb,influxdb…]）。
  
• 27~38行：构造规则管理服务(ruleManager)，包括规则的执行和告警的发送等；
  
• 54行：构造Web管理服务
  
• 56~60行：加载告警规则，并同步到相关服务
• 65~77行：告警规则动态加载处理，以Linux信号量的通知方式实现；
  
• 81~96行：启动指标存储引擎以及程序退出引擎析构处理；
  
• 89~101行：注册prometheus组件内部所输出的系统指标；