从 golang 中手动将 OpenTelemetry 上下文提取到字符串中？

Question

我正在构建一个简单的客户端服务器应用程序，我想通过客户端执行跟踪到调用第二个服务器微服务的服务器微服务。

简单来说，并不比CLI -> ServiceA -> ServiceB复杂

我面临的挑战是如何序列化上下文——我看过的大多数文档似乎都在执行某种形式的自动 HTTP header 注入（例如 https://opentelemetry.lightstep.com/core-concepts/context-propagation/），但我无权访问它。我需要序列化（我认为）客户端中 trace/span 的上下文并将其推送到服务器，我将在服务器上重新水化它。（请注意，我希望这个更简单，但我无法弄清楚）。

所以 object 看起来像这样（称为“工作”）：

    args := &types.SubmitArgs{
        SerializedOtelContext: serializedOtelContext,
    }

    job := &types.Job{}

    tracer := otel.GetTracerProvider().Tracer("myservice.org")
    _, span := tracer.Start(ctx, "Submitting Job to RPC")
    err := system.JsonRpcMethod(rpcHost, rpcPort, "Submit", args, job)

提交JsonRpcMethod的函数在这里：

func JsonRpcMethod(
    host string,
    port int,
    method string,
    req, res interface{},
) error {
    client, err := rpc.DialHTTP("tcp", fmt.Sprintf("%s:%d", host, port))
    if err != nil {
        return fmt.Errorf("Error in dialing. %s", err)
    }
    return client.Call(fmt.Sprintf("JobServer.%s", method), req, res)
}

接收它的函数在这里：

func (server *JobServer) Submit(args *types.SubmitArgs, reply *types.Job) error {
    //nolint
    job, err := server.RequesterNode.Scheduler.SubmitJob(args.Spec, args.Deal)
    if err != nil {
        return err
    }
    *reply = *job
    return nil
}

我的问题是如何在接收功能（上面的“提交”）中从发件人那里提取 trace/span？

Answer 1

这里有一个小程序来说明用法。希望这能说明问题。

package main

import (
    "context"
    "fmt"

    "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
    "go.opentelemetry.io/otel/propagation"
    sdktrace "go.opentelemetry.io/otel/sdk/trace"
)

func main() {

    // common init
    // You may also want to set them as globals
    exp, _ := stdouttrace.New(stdouttrace.WithPrettyPrint())
    bsp := sdktrace.NewSimpleSpanProcessor(exp) // You should use batch span processor in prod
    tp := sdktrace.NewTracerProvider(
        sdktrace.WithSampler(sdktrace.AlwaysSample()),
        sdktrace.WithSpanProcessor(bsp),
    )

    propgator := propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{})

    ctx, span := tp.Tracer("foo").Start(context.Background(), "parent-span-name")
    defer span.End()

    // Serialize the context into carrier
    carrier := propagation.MapCarrier{}
    propgator.Inject(ctx, carrier)
    // This carrier is sent accros the process
    fmt.Println(carrier)

    // Extract the context and start new span as child
    // In your receiving function
    parentCtx := propgator.Extract(context.Background(), carrier)
    _, childSpan := tp.Tracer("foo").Start(parentCtx, "child-span-name")
    childSpan.AddEvent("some-dummy-event")
    childSpan.End()
}

从 golang 中手动将 OpenTelemetry 上下文提取到字符串中？

Manually extracting OpenTelemetry context from golang into a string?

go

open-telemetry