链路追踪

Tracing 中间件使用 OpenTelemetry 实现了链路追踪。

配置

有两种方法可用于使用WithTracerProvider() and WithPropagator()进行配置。

`WithTracerProvider`

func WithTracerProvider(provider trace.TracerProvider) Option {
    return func(opts *options) {
        opts.TracerProvider = provider
    }
}

WithTracerProvider 用于设置 provider，它接收的参数为 trace.TracerProvider。

`WithPropagator`

func WithPropagator(propagator propagation.TextMapPropagator) Option {
    return func(opts *options) {
        opts.Propagator = propagator
    }
}

WithPropagator 用于设置 text map propagator，它接收的参数为 propagation.TextMapPropagator。

使用方法

server 中使用 tracing 采集数据

package server

import (
  "github.com/go-kratos/kratos/v2/middleware/tracing"
  "github.com/go-kratos/kratos/v2/transport/grpc"

  "go.opentelemetry.io/otel"
  "go.opentelemetry.io/otel/attribute"
  "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
  "go.opentelemetry.io/otel/sdk/resource"
  tracesdk "go.opentelemetry.io/otel/sdk/trace"
  semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
)

// 设置全局trace
func initTracer(endpoint string) error {
  // 创建 exporter
  exporter, err := otlptracehttp.New(context.Background(),
    otlptracehttp.WithEndpoint(endpoint),
    otlptracehttp.WithInsecure(),
  )
  if err != nil {
    return err
  }
  tp := tracesdk.NewTracerProvider(
    // 将基于父span的采样率设置为100%
    tracesdk.WithSampler(tracesdk.ParentBased(tracesdk.TraceIDRatioBased(1.0))),
    // 始终确保在生产中批量处理
    tracesdk.WithBatcher(exporter),
    // 在资源中记录有关此应用程序的信息
    tracesdk.WithResource(resource.NewSchemaless(
      semconv.ServiceNameKey.String("kratos-trace"),
      attribute.String("exporter", "otlp"),
      attribute.Float64("float", 312.23),
    )),
  )
  otel.SetTracerProvider(tp)
  return nil
}

// NewGRPCServer new a gRPC server.
func NewGRPCServer(c *conf.Server, executor *service.ExecutorService) *grpc.Server {
  err := initTracer("localhost:4318")
  if err != nil {
    panic(err)
  }
  //tr := otel.Tracer("component-main")
  var opts = []grpc.ServerOption{
    grpc.Middleware(
      tracing.Server(),
    ),
  }
  // ...
}

client 中使用 tracing 采集数据

package client

import (
  "context"

  "github.com/go-kratos/kratos/v2/middleware/tracing"
  "github.com/go-kratos/kratos/v2/transport/grpc"

  "go.opentelemetry.io/otel"
  "go.opentelemetry.io/otel/attribute"
  "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
  "go.opentelemetry.io/otel/sdk/resource"
  tracesdk "go.opentelemetry.io/otel/sdk/trace"
  semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
  googlegrpc "google.golang.org/grpc"
)

// 设置全局trace
func initTracer(endpoint string) error {
  // 创建 exporter
  exporter, err := otlptracehttp.New(context.Background(),
    otlptracehttp.WithEndpoint(endpoint),
    otlptracehttp.WithInsecure(),
  )
  if err != nil {
    return err
  }
  tp := tracesdk.NewTracerProvider(
    // 将基于父span的采样率设置为100%
    tracesdk.WithSampler(tracesdk.ParentBased(tracesdk.TraceIDRatioBased(1.0))),
    // 始终确保在生产中批量处理
    tracesdk.WithBatcher(exporter),
    // 在资源中记录有关此应用程序的信息
    tracesdk.WithResource(resource.NewSchemaless(
      semconv.ServiceNameKey.String("kratos-trace"),
      attribute.String("exporter", "otlp"),
      attribute.Float64("float", 312.23),
    )),
  )
  otel.SetTracerProvider(tp)
  return nil
}

func grpcCli() (*googlegrpc.ClientConn, error) {
  // 如果本项目没有初始化initTracer 请初始化
  return grpc.DialInsecure(
    context.Background(),
    grpc.WithMiddleware(
      tracing.Client(),
    ),
  )
}

自动采集数据

如果不想手动修改代码，您还可以使用一些框架进行OpenTelemetry数据的自动采集，比如Alibaba Go Auto Instrumentation (后续将正式捐赠至OpenTelemetry官方)。

您可以参考文档来编译您的Kratos应用。