standard/open_telemetry/serverA/serverA.go

package main

import (
	"context"
	"log"
	"math/rand"
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
	"go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/propagation"

	otel2 "standard/open_telemetry/otel"
)

const (
	name       = "app2"
	addr       = ":8081"
	otelTarget = "localhost:4317"
)

func main() {
	ctx := context.Background()
	serviceName := "ServiceA"                                       // 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)

	// Setup Gin router
	router := gin.Default()
	router.Use(otelgin.Middleware(name))
	router.GET("/work", work)

	// Start the server
	err = router.Run(addr)
	if err != nil {
		log.Panicf("Failed to start the server: %v", err)
	}
}

func work(c *gin.Context) {
	duration := time.Duration(rand.Intn(3)) * time.Second
	time.Sleep(duration)
	c.JSON(http.StatusOK, gin.H{
		"message":         "Hello from app2!",
		"duration_second": duration.Seconds(),
	})
}

// callServiceB 调用 ServiceB 的 /serviceB 接口
func callServiceB(ctx context.Context) {
	url := "http://localhost:8081/serviceB" // ServiceB 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 ServiceB 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 ServiceB: %v", err)
		return
	}
	defer resp.Body.Close()

	log.Println("Called ServiceB successfully")
}