standard/open_telemetry/serverB/serverB.go

package main

import (
	"context"
	"log"
	"net/http"

	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/propagation"

	otel2 "standard/open_telemetry/otel"
)

func main() {
	ctx := context.Background()
	serviceName := "ServiceB"                                        // 服务名称
	jaegerEndpoint := "http://7162377c.r11.cpolar.top//api/v2/spans" // Jaeger 的 Collector Endpoint

	// 初始化 OpenTelemetry SDK
	shutdown, err := otel2.SetupOTelSDK(ctx, serviceName, jaegerEndpoint)
	if err != nil {
		log.Fatalf("Failed to setup OpenTelemetry SDK: %v", err)
	}
	defer shutdown(ctx)

	// 注册 /serviceB 路由
	http.HandleFunc("/serviceB", func(w http.ResponseWriter, r *http.Request) {
		ctx, span := otel.Tracer(serviceName).Start(r.Context(), "ServiceB.serviceB") // 创建一个 Span
		defer span.End()

		// 调用 ServiceC
		callServiceC(ctx)
	})

	log.Println("Starting ServiceB on :8081")
	log.Fatal(http.ListenAndServe(":8081", otelhttp.NewHandler(http.DefaultServeMux, serviceName)))
}

// callServiceC 调用 ServiceC 的 /serviceC 接口
func callServiceC(ctx context.Context) {
	url := "http://localhost:8082/serviceC" // ServiceC 的地址
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		log.Printf("Failed to create request: %v", err)
		return
	}

	// 将上下文中的追踪信息注入到请求头中，以便 ServiceC 可以继续追踪
	otel.GetTextMapPropagator().Inject(ctx, propagation.HeaderCarrier(req.Header))
	log.Printf("Request headers: %+v", req.Header)

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		log.Printf("Failed to call ServiceC: %v", err)
		return
	}
	defer resp.Body.Close()

	log.Println("Called ServiceC successfully")
}