Caddy 源码分析

base

run.go

init function 注册配置文件 信号捕获 文件解析等

func init() {
	caddy.TrapSignals() // 信号捕获程序
	// ---> 从此处开始都是证书相关的配置 使用 CertMagic 第三方库
	flag.BoolVar(&certmagic.Default.Agreed, "agree", false, "Agree to the CA's Subscriber Agreement")
	flag.StringVar(&certmagic.Default.CA, "ca", certmagic.Default.CA, "URL to certificate authority's ACME server directory")
	flag.StringVar(&certmagic.Default.DefaultServerName, "default-sni", certmagic.Default.DefaultServerName, "If a ClientHello ServerName is empty, use this ServerName to choose a TLS certificate")
	flag.BoolVar(&certmagic.Default.DisableHTTPChallenge, "disable-http-challenge", certmagic.Default.DisableHTTPChallenge, "Disable the ACME HTTP challenge")
	flag.BoolVar(&certmagic.Default.DisableTLSALPNChallenge, "disable-tls-alpn-challenge", certmagic.Default.DisableTLSALPNChallenge, "Disable the ACME TLS-ALPN challenge")
	flag.StringVar(&disabledMetrics, "disabled-metrics", "", "Comma-separated list of telemetry metrics to disable")
  // <--- 以上是证书相关设置
	flag.StringVar(&conf, "conf", "", "Caddyfile to load (default \""+caddy.DefaultConfigFile+"\")")
	flag.StringVar(&cpu, "cpu", "100%", "CPU cap")
	flag.BoolVar(&printEnv, "env", false, "Enable to print environment variables")
	flag.StringVar(&envFile, "envfile", "", "Path to file with environment variables to load in KEY=VALUE format")
	flag.BoolVar(&fromJSON, "json-to-caddyfile", false, "From JSON stdin to Caddyfile stdout")
	flag.BoolVar(&plugins, "plugins", false, "List installed plugins")
	flag.StringVar(&certmagic.Default.Email, "email", "", "Default ACME CA account email address")
	flag.DurationVar(&certmagic.HTTPTimeout, "catimeout", certmagic.HTTPTimeout, "Default ACME CA HTTP timeout")
	flag.StringVar(&logfile, "log", "", "Process log file")
	flag.BoolVar(&logTimestamps, "log-timestamps", true, "Enable timestamps for the process log")
	flag.IntVar(&logRollMB, "log-roll-mb", 100, "Roll process log when it reaches this many megabytes (0 to disable rolling)")
	flag.BoolVar(&logRollCompress, "log-roll-compress", true, "Gzip-compress rolled process log files")
	flag.StringVar(&caddy.PidFile, "pidfile", "", "Path to write pid file")
	flag.BoolVar(&caddy.Quiet, "quiet", false, "Quiet mode (no initialization output)")
	flag.StringVar(&revoke, "revoke", "", "Hostname for which to revoke the certificate")
	flag.StringVar(&serverType, "type", "http", "Type of server to run")
	flag.BoolVar(&toJSON, "caddyfile-to-json", false, "From Caddyfile stdin to JSON stdout")
	flag.BoolVar(&version, "version", false, "Show version")
	flag.BoolVar(&validate, "validate", false, "Parse the Caddyfile but do not start the server")

	caddy.RegisterCaddyfileLoader("flag", caddy.LoaderFunc(confLoader)) // 注册caddy文件/Stdin读取器
	caddy.SetDefaultCaddyfileLoader("default", caddy.LoaderFunc(defaultLoader)) // 读取默认配置文件
}

run function main文件调用的函数

func Run() {
	flag.Parse()

	module := getBuildModule()
	cleanModVersion := strings.TrimPrefix(module.Version, "v")

	caddy.AppName = appName
	caddy.AppVersion = module.Version
	caddy.OnProcessExit = append(caddy.OnProcessExit, certmagic.CleanUpOwnLocks) // 关闭应该调用的函数列表
	certmagic.UserAgent = appName + "/" + cleanModVersion

	if !logTimestamps {
		// 禁用时间戳记
		log.SetFlags(0)
	}

	// 在发生任何异常情况之前设置进程日志
	switch logfile {
	case "stdout":
		log.SetOutput(os.Stdout)
	case "stderr":
		log.SetOutput(os.Stderr)
	case "":
		log.SetOutput(ioutil.Discard)
	default:
		if logRollMB > 0 {
			log.SetOutput(&lumberjack.Logger{
				Filename:   logfile,
				MaxSize:    logRollMB,
				MaxAge:     14,
				MaxBackups: 10,
				Compress:   logRollCompress,
			})
		} else {
			err := os.MkdirAll(filepath.Dir(logfile), 0755)
			if err != nil {
				mustLogFatalf("%v", err)
			}
			f, err := os.OpenFile(logfile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
			if err != nil {
				mustLogFatalf("%v", err)
			}
			// 不要关闭文件；在整个过程中日志应该是可写的
			log.SetOutput(f)
		}
	}

	// 尽快加载所有其他环境
	if err := LoadEnvFromFile(envFile); err != nil {
		mustLogFatalf("%v", err)
	}

	if printEnv {
		for _, v := range os.Environ() {
			fmt.Println(v)
		}
	}

	// 初始化遥测客户端
	if EnableTelemetry {
		err := initTelemetry()
		if err != nil {
			mustLogFatalf("[ERROR] Initializing telemetry: %v", err)
		}
	} else if disabledMetrics != "" {
		mustLogFatalf("[ERROR] Cannot disable specific metrics because telemetry is disabled")
	}

	// 检查一次性动作
	if revoke != "" {
		err := caddytls.Revoke(revoke)
		if err != nil {
			mustLogFatalf("%v", err)
		}
		fmt.Printf("Revoked certificate for %s\n", revoke)
		os.Exit(0)
	}
	if version {
		if module.Sum != "" {
			// 具有已知版本的构建也将具有校验和
			fmt.Printf("Caddy %s (%s)\n", module.Version, module.Sum)
		} else {
			fmt.Println(module.Version)
		}
		os.Exit(0)
	}
	if plugins {
		fmt.Println(caddy.DescribePlugins())
		os.Exit(0)
	}

	//检查是否只需要执行Caddyfile转换并退出
	checkJSONCaddyfile()

	// 设置CPU上限
	err := setCPU(cpu)
	if err != nil {
		mustLogFatalf("%v", err)
	}

	// 执行启动事件
	caddy.EmitEvent(caddy.StartupEvent, nil)

	// 获取Caddyfile输入
	caddyfileinput, err := caddy.LoadCaddyfile(serverType)
	if err != nil {
		mustLogFatalf("%v", err)
	}

	if validate {
		err := caddy.ValidateAndExecuteDirectives(caddyfileinput, nil, true)
		if err != nil {
			mustLogFatalf("%v", err)
		}
		msg := "Caddyfile is valid"
		fmt.Println(msg)
		log.Printf("[INFO] %s", msg)
		os.Exit(0)
	}

	// 开始之前记录Caddy版本
	log.Printf("[INFO] Caddy version: %s", module.Version)

	// 启动引擎
	instance, err := caddy.Start(caddyfileinput)
	if err != nil {
		mustLogFatalf("%v", err)
	}

	// 开始遥测（如果禁用遥测，则为无操作）
	telemetry.Set("caddy_version", module.Version)
	telemetry.Set("num_listeners", len(instance.Servers()))
	telemetry.Set("server_type", serverType)
	// 设置系统环境和cpu
	telemetry.Set("os", runtime.GOOS)
	telemetry.Set("arch", runtime.GOARCH)
	telemetry.Set("cpu", struct {
		BrandName  string `json:"brand_name,omitempty"`
		NumLogical int    `json:"num_logical,omitempty"`
		AESNI      bool   `json:"aes_ni,omitempty"`
	}{
		BrandName:  cpuid.CPU.BrandName,
		NumLogical: runtime.NumCPU(),
		AESNI:      cpuid.CPU.AesNi(),
	})
	if containerized := detectContainer(); containerized {
		telemetry.Set("container", containerized)
	}
	telemetry.StartEmitting()

	// 转动你的拇指(实指等待caddy服务器声明周期完结)
	instance.Wait()
}

总结

看完 caddy 的 run 函数，了解了程序的启动配置了哪些东西，相应的会有一些问题。带着这些问题继续看源码，能够深入了解 caddy 内的逻辑。

• caddy.Input 的内在读取 caddyfile 的操作
• Loader 可以看出也是可以自定义的，他实际涉及到 Caddy 较为重要的 接收配置，安装配置的操作部分。它会读取 token 给 plugin 配置时 给 controller 消费，这里多的名词是来自于 caddy 的配置部分
• caddy.EmitEvent 是怎样启动各 caddy 插件的
• caddy.ServerType 除了 HTTP 还有什么（插件会对应相应的服务器的）
• instance 可以看出是 caddy 服务器的实例，它具体的设置逻辑是什么来获得 插件装配的能力的。他是怎样作为服务器服务的
• 遥测模块的接入（caddy 2已经不用了）
• 其他的就是一些方便的选项了。

本文逻辑根据知乎相关文章阅览