怎样用Golang构建可观测性平台 集成OpenTelemetry

otlptrace

jaeger

package main

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

    "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
    "go.opentelemetry.io/otel"
    "go.opentelemetry.io/otel/attribute"
    "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
    "go.opentelemetry.io/otel/metric"
    "go.opentelemetry.io/otel/propagation"
    "go.opentelemetry.io/otel/sdk/resource"
    sdktrace "go.opentelemetry.io/otel/sdk/trace"
    semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
    "google.golang.org/grpc"
    "google.golang.org/grpc/credentials/insecure"
)

var tracer = otel.Tracer("my-service-tracer")
var meter = otel.Meter("my-service-meter")

func initTracer() *sdktrace.TracerProvider {
    ctx := context.Background()

    // 创建OTLP gRPC导出器
    conn, err := grpc.NewClient(
        "localhost:4317", // OpenTelemetry Collector OTLP gRPC 端口
        grpc.WithTransportCredentials(insecure.NewCredentials()),
        grpc.WithBlock(),
    )
    if err != nil {
        log.Fatalf("failed to create gRPC client: %v", err)
    }

    traceExporter, err := otlptracegrpc.New(ctx, otlptracegrpc.WithGRPCConn(conn))
    if err != nil {
        log.Fatalf("failed to create trace exporter: %v", err)
    }

    // 配置资源，描述服务自身信息
    res, err := resource.New(ctx,
        resource.WithAttributes(
            semconv.ServiceNameKey.String("my-golang-app"),
            semconv.ServiceVersionKey.String("1.0.0"),
            attribute.String("environment", "development"),
        ),
    )
    if err != nil {
        log.Fatalf("failed to create resource: %v", err)
    }

    // 创建TracerProvider
    bsp := sdktrace.NewBatchSpanProcessor(traceExporter)
    tp := sdktrace.NewTracerProvider(
        sdktrace.WithResource(res),
        sdktrace.WithSpanProcessor(bsp),
        sdktrace.WithSampler(sdktrace.AlwaysSample()), // 总是采样
    )

    // 全局注册TracerProvider和文本图传播器
    otel.SetTracerProvider(tp)
    otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(
        propagation.TraceContext{},
        propagation.Baggage{},
    ))
    return tp
}

func main() {
    tp := initTracer()
    defer func() {
        if err := tp.Shutdown(context.Background()); err != nil {
            log.Printf("Error shutting down tracer provider: %v", err)
        }
    }()

    // 示例：HTTP请求处理
    http.Handle("/hello", otelhttp.NewHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        ctx, span := tracer.Start(r.Context(), "hello-handler")
        defer span.End()

        // 模拟一些工作
        time.Sleep(100 * time.Millisecond)

        // 记录事件
        span.AddEvent("processing request")

        // 模拟调用另一个内部函数
        callInternalFunction(ctx)

        fmt.Fprintln(w, "Hello, OpenTelemetry!")
    }), "hello-route"))

    log.Println("Server started on :8080")
    log.Fatal(http.ListenAndServe(":8080", nil))
}

func callInternalFunction(ctx context.Context) {
    _, span := tracer.Start(ctx, "internal-function")
    defer span.End()

    // 模拟更深层次的逻辑
    time.Sleep(50 * time.Millisecond)

    // 记录指标
    counter, err := meter.Int64Counter("my_counter")
    if err != nil {
        log.Printf("Failed to create counter: %v", err)
    } else {
        counter.Add(ctx, 1, metric.WithAttributes(attribute.String("operation", "internal_call")))
    }
}

// 注意：日志集成通常需要使用OpenTelemetry Logger SDK，目前还在稳定阶段，
// 常见的做法是使用现有的日志库（如zap, logrus）并配置其输出到OTLP/Loki等日志后端，
// 或者将trace_id/span_id注入到日志字段中，实现日志与追踪的关联。

TracerProvider

otelhttp.NewHandler

tracer.Start

context.Context

context.Context

context.Context

context.Context

otelhttp.NewHandler

Context

Context

func processOrder(ctx context.Context, orderID string) error {
    // 从传入的ctx中创建新的span
    ctx, span := tracer.Start(ctx, "process-order")
    defer span.End()

    // 假设这里需要调用另一个服务
    // 在发起gRPC或HTTP请求时，确保将ctx传递给客户端，以便传播追踪上下文
    // 例如：
    // client := &http.Client{Transport: otelhttp.NewTransport(http.DefaultTransport)}
    // req, _ := http.NewRequestWithContext(ctx, "GET", "http://another-service/api/data", nil)
    // resp, err := client.Do(req)
    // ...

    span.AddEvent("order processed successfully", trace.WithAttributes(attribute.String("order.id", orderID)))
    return nil
}

propagation.TextMapPropagator

context.Context

traceparent

tracestate

context.Context

propagation.NewCompositeTextMapPropagator

propagation.TraceContext{}

propagation.Baggage{}

Context

Context

Context

trace_id

span_id