trace

Micro通过Wrapper实现了三种trace接口，aswxray,opencensus,opentracing,这里主要关注opentracing，opentracing已成为行业标准。

opentracing

要引入OpenTracing方案，只需要opentracing.NewClientWrapper加入Client或者Server即可。

func NewClientWrapper(ot opentracing.Tracer) client.Wrapper {

	return func(c client.Client) client.Client {

		return &otWrapper{ot, c}

	}

}

opentracing.NewClientWrapper方法入参是实现OpenTracing的接口opentracing.Tracer

type Tracer interface {

    StartSpan(operationName string, opts ...StartSpanOption) Span

    Inject(sm SpanContext, format interface{}, carrier interface{}) error

    Extract(format interface{}, carrier interface{}) (SpanContext, error)

}

jaeger

部署一个测试的jaeger,服务器地址:192.168.8.144，Agent的默认端口是5775。

/home/service/base/jaeger

[root@localhost jaeger]# ll

total 158444

-rwxr-xr-x 1 root root 14565068 Nov 16 19:35 example-hotrod

-rwxr-xr-x 1 root root 20387089 Nov 16 19:35 jaeger-agent

-rwxr-xr-x 1 root root 38456594 Nov 16 19:35 jaeger-all-in-one

-rwxr-xr-x 1 root root 29731462 Nov 16 19:35 jaeger-collector

-rwxr-xr-x 1 root root 25523281 Nov 16 19:35 jaeger-ingester

-rwxr-xr-x 1 root root 33563911 Nov 16 19:35 jaeger-query

-rwxr-xr-x 1 root root       43 Nov 16 19:36 run

-rw-r--r-- 1 root root     1939 Nov 16 19:36 x.log

[root@localhost jaeger]# cat run

nohup ./jaeger-all-in-one  >> x.log 2>&1 &

jaeger是一款分布式的追踪系统，实现了opentracingAPI标准，也是Go生态的，是CNCF成员。

func TestJaeger(t *testing.T) {

	cfg := config.Configuration{

		ServiceName: "MicroTestService",//自定义服务名称

		Sampler: &config.SamplerConfig{

			Type:  "const",

			Param: 1,

		},

		Reporter: &config.ReporterConfig{

			LogSpans:            true,

			BufferFlushInterval: 1 * time.Second,

			LocalAgentHostPort:  "192.168.8.144:5775",//jaeger agent

		},

	}

	tracer, closer, err := cfg.NewTracer()

	if err != nil {

		t.Error(err)

		return

	}

	defer closer.Close()

	r := mock.NewRegistry()

	s := selector.NewSelector(selector.Registry(r))

	c := client.NewClient(

		// set the selector

		client.Selector(s),

		// add the trace wrapper

		client.Wrap(NewClientWrapper(tracer)),

	)

	req := c.NewRequest("test.service", "Test.Method", map[string]string{

		"foo": "bar",

	}, client.WithContentType("application/json"))

	var rsp map[string]interface{}

	c.Call(context.TODO(), req, rsp)

	t.Log(rsp)

}

浏览器访问:http://192.168.8.144:16686/search可以发现有服务MicroTestService的访问追踪了