opentracing

opentracing介绍和规范

OpenTracing API for Go

使用jaeger来进行跟踪

jaeger github

jaeger 官网

使用教程

安装

docker

 docker run -d -p 5775:5775/udp -p 16686:16686 jaegertracing/all-in-one:latest 

simple trace

    //初始化jaeger
    func initJaeger(service string) (opentracing.Tracer, io.Closer) {
        cfg := &config.Configuration{
            Sampler: &config.SamplerConfig{
                Type:  "const",
                Param: 1,
            },
            Reporter: &config.ReporterConfig{
                LogSpans: true,
            },
        }
        tracer, closer, err := cfg.New(service, config.Logger(jaeger.StdLogger))
        if err != nil {
            panic(fmt.Sprintf("ERROR: cannot init Jaeger: %v\n", err))
        }
        return tracer, closer
    }

    //初始化
	tracer, closer := initJaeger("hello-world")
	defer closer.Close()
    //开始一个span
	span := tracer.StartSpan("say-hello")
	span.SetTag("hello-to", helloTo)
	defer span.Finish()
	//向下一个span传递
	func test(rootSpan opentracing.Span, helloStr string) {
    	span := rootSpan.Tracer().StartSpan("test",opentracing.ChildOf(rootSpan.Context()))
    	defer span.Finish()
    
    	println(helloStr)
    	span.LogKV("event", "test")
    }
    
	

使用context来存span

    //初始化
	tracer, closer := initJaeger("hello-world")
	defer closer.Close()
	opentracing.SetGlobalTracer(tracer)//这个必须设置
    //开始一个span
	span := tracer.StartSpan("say-hello")
	span.SetTag("hello-to", helloTo)
	defer span.Finish()
	//使用context进行span的传递
	ctx := context.Background()
	ctx = opentracing.ContextWithSpan(ctx,span)
	test(ctx,"test")
	
	//test函数
	func test(ctx context.Context, helloStr string) {
	    //取出根span
    	span,_ := opentracing.StartSpanFromContext(ctx,"test")
    	defer span.Finish()
    
    	println(helloStr)
    	span.LogKV("event", "test")
    	//如果还需要向下传递,重新设置span的上下文
    	ctx = opentracing.ContextWithSpan(ctx,span)
        test2(ctx,"test2")
    }
	

服务间传递

实现

OpenTracing API在Tracer界面中提供了两个功能来实现: Inject(spanContext, format, carrier)以及Extract(format, carrier)

该format参数指的是OpenTracing API定义的三种标准编码之一：

TextMap:其中span上下文被编码为字符串键值对的集合，
Binary:其中span上下文被编码为不透明的字节数组，
HTTPHeaders:类似于TextMap，除了密钥必须安全用作HTTP头。

这carrier是对底层RPC框架的抽象。例如，TextMap格式的载体是一个允许跟踪器通过Set(key, value)函数写入键值对的接口，而二进制格式的载体只是一个io.Writer

Inject(注入)

 //调用端
import (
    "github.com/opentracing/opentracing-go/ext"
)


ext.SpanKindRPCClient.Set(span)
ext.HTTPUrl.Set(span, url)
ext.HTTPMethod.Set(span, "GET")
span.Tracer().Inject(
    span.Context(),
    opentracing.HTTPHeaders,
    opentracing.HTTPHeadersCarrier(req.Header),
)

Extract(提取)

		spanCtx, _ := tracer.Extract(opentracing.HTTPHeaders, opentracing.HTTPHeadersCarrier(r.Header))
		span := tracer.StartSpan("format", ext.RPCServerOption(spanCtx))
		defer span.Finish()
		

数据传递

//父
span.SetBaggageItem("greeting", greeting) //设置
//子
greeting := span.BaggageItem("greeting") //获取

额外：

http请求的详细时间