本文将介绍如何在 gRPC 分布式场景中，实现 API 的日志追踪。

什么是 API 日志追踪？

一个 API 请求会跨多个微服务，我们希望通过一个唯一的 ID 检索到整个链路的日志。

我们将会使用rk-boot来启动 gRPC 服务
安装
go get github.com/rookie-ninja/rk-boot
快速开始
rk-boot 默认集成了 grpc-gateway，并且会默认启动。
我们会创建 /api/v1/greeter API 进行验证，同时开启 logging, meta 和 tracing 拦截器以达到目的。
1. 创建 api/v1/greeter.proto
syntax = "proto3";

package api.v1;

option go_package = "api/v1/greeter";

service Greeter {
  rpc Greeter (GreeterRequest) returns (GreeterResponse) {}
}

message GreeterRequest {
  string name = 1;
}

message GreeterResponse {
  string message = 1;}
2. 创建 api/v1/gw_mapping.yaml
type: google.api.Service
config_version: 3

# Please refer google.api.Http in https://github.com/googleapis/googleapis/blob/master/google/api/http.proto file for details.
http:
  rules:
    - selector: api.v1.Greeter.Greeter
      get: /api/v1/greeter
3. 创建 buf.yaml
version: v1beta1
name: github.com/rk-dev/rk-demo
build:
  roots:
    - api
4. 创建 buf.gen.yaml
version: v1beta1
plugins:
  # protoc-gen-go needs to be installed, generate go files based on proto files
  - name: go
    out: api/gen
    opt:
     - paths=source_relative
  # protoc-gen-go-grpc needs to be installed, generate grpc go files based on proto files
  - name: go-grpc
    out: api/gen
    opt:
      - paths=source_relative
      - require_unimplemented_servers=false
  # protoc-gen-grpc-gateway needs to be installed, generate grpc-gateway go files based on proto files
  - name: grpc-gateway
    out: api/gen
    opt:
      - paths=source_relative
      - grpc_api_configuration=api/v1/gw_mapping.yaml
  # protoc-gen-openapiv2 needs to be installed, generate swagger config files based on proto files
  - name: openapiv2
    out: api/gen
    opt:
      - grpc_api_configuration=api/v1/gw_mapping.yaml
5. 编译 proto file
$ buf generate如下的文件会被创建。$ tree api/gen
api/gen
└── v1
    ├── greeter.pb.go
    ├── greeter.pb.gw.go
    ├── greeter.swagger.json
    └── greeter_grpc.pb.go
 
1 directory, 4 files
6. 创建 bootA.yaml & serverA.go
Server-A 监听 1949 端口，并且发送请求给 Server-B。
我们通过 rkgrpcctx.InjectSpanToNewContext() 方法把 Tracing 信息注入到 Context 中，发送给 Server-B。

---
grpc:
  - name: greeter                   # Name of grpc entry
    port: 1949                      # Port of grpc entry
    enabled: true                   # Enable grpc entry
    interceptors:
      loggingZap:
        enabled: true
      meta:
        enabled: true
      tracingTelemetry:
        enabled: true

package main

import (
    "context"
    "demo/api/gen/v1"
    "fmt"
    "github.com/rookie-ninja/rk-boot"
    "github.com/rookie-ninja/rk-grpc/interceptor/context"
    "google.golang.org/grpc"
)

// Application entrance.
func main() {
    // Create a new boot instance.
    boot := rkboot.NewBoot(rkboot.WithBootConfigPath("bootA.yaml"))

    // Get grpc entry with name
    grpcEntry := boot.GetGrpcEntry("greeter")
    grpcEntry.AddRegFuncGrpc(registerGreeter)
    grpcEntry.AddRegFuncGw(greeter.RegisterGreeterHandlerFromEndpoint)

    // Bootstrap
    boot.Bootstrap(context.Background())

    // Wait for shutdown sig
    boot.WaitForShutdownSig(context.Background())
}

func registerGreeter(server *grpc.Server) {
    greeter.RegisterGreeterServer(server, &GreeterServer{})
}

type GreeterServer struct{}

func (server *GreeterServer) Greeter(ctx context.Context, request *greeter.GreeterRequest) (*greeter.GreeterResponse, error) {
    // Call serverB at 2008 with grpc client
    opts := []grpc.DialOption{
        grpc.WithBlock(),
        grpc.WithInsecure(),
    }
    conn, _ := grpc.Dial("localhost:2008", opts...)
    defer conn.Close()
    client := greeter.NewGreeterClient(conn)

    // Inject current trace information into context
    newCtx := rkgrpcctx.InjectSpanToNewContext(ctx)
    client.Greeter(newCtx, &greeter.GreeterRequest{Name: "A"})

    return &greeter.GreeterResponse{
        Message: fmt.Sprintf("Hello %s!", request.Name),
    }, nil

7. 创建 bootB.yaml & serverB.go

Server-B 监听 2008 端口。

--- grpc: - name: greeter # Name of grpc entry port: 2008 # Port of grpc entry enabled: true # Enable grpc entry interceptors: loggingZap: enabled: true meta: enabled: true tracingTelemetry: enabled: truepackage main import ( "context" "demo/api/gen/v1" "fmt" "github.com/rookie-ninja/rk-boot" "google.golang.org/grpc" ) // Application entrance. func main() { // Create a new boot instance. boot := rkboot.NewBoot(rkboot.WithBootConfigPath("bootB.yaml")) // Get grpc entry with name grpcEntry := boot.GetGrpcEntry("greeter") grpcEntry.AddRegFuncGrpc(registerGreeterB) grpcEntry.AddRegFuncGw(greeter.RegisterGreeterHandlerFromEndpoint) // Bootstrap boot.Bootstrap(context.Background()) // Wait for shutdown sig boot.WaitForShutdownSig(context.Background()) } func registerGreeterB(server *grpc.Server) { greeter.RegisterGreeterServer(server, &GreeterServerB{}) } type GreeterServerB struct{} func (server *GreeterServerB) Greeter(ctx context.Context, request *greeter.GreeterRequest) (*greeter.GreeterResponse, error) { return &greeter.GreeterResponse{ Message: fmt.Sprintf("Hello %s!", request.Name), }, nil }

8. 文件夹结构

├── api │ ├── gen │ │ └── v1 │ │ ├── greeter.pb.go │ │ ├── greeter.pb.gw.go │ │ ├── greeter.swagger.json │ │ └── greeter_grpc.pb.go │ └── v1 │ ├── greeter.proto │ └── gw_mapping.yaml ├── bootA.yaml ├── bootB.yaml ├── buf.gen.yaml ├── buf.yaml ├── go.mod ├── go.sum ├── serverA.go └── serverB.go

9. 启动 ServerA & ServerB

$ go run serverA.go $ go run serverB.go

10. 往 ServerA 发送请求

¥ curl "localhost:1949/api/v1/greeter?name=rk-dev"

11. 验证日志

两个服务的日志中，会有同样的 traceId，不同的 requestId。

我们可以通过 grep traceId 来追踪 RPC。

• ServerA

------------------------------------------------------------------------ endTime=2021-10-20T00:02:21.739688+08:00 ... ids={"eventId":"0d145356-998a-4999-ab62-6f1b805274a0","requestId":"0d145356-998a-4999-ab62-6f1b805274a0","traceId":"c36a45eb076066df39fa407174012369"} ... operation=/api.v1.Greeter/Greeter resCode=OK eventStatus=Ended EOE

• ServerB

------------------------------------------------------------------------ endTime=2021-10-20T00:02:21.739125+08:00 ... ids={"eventId":"8858a6eb-e953-42ad-bdc3-c466bbbd798e","requestId":"8858a6eb-e953-42ad-bdc3-c466bbbd798e","traceId":"c36a45eb076066df39fa407174012369"} ... operation=/api.v1.Greeter/Greeter resCode=OK eventStatus=Ended EOE

概念

当我们没有使用例如 jaeger 调用链服务的时候，我们希望通过日志来追踪分布式系统里的 RPC 请求。

rk-boot 的拦截器会通过 openTelemetry 库来向日志写入 traceId 来追踪 RPC。

当启动了日志拦截器，原数据拦截器，调用链拦截器的时候，拦截器会往日志里写入如下三种 ID。

EventId

当启动了日志拦截器，EventId 会自动生成。

--- grpc: - name: greeter # Name of grpc entry port: 1949 # Port of grpc entry enabled: true # Enable grpc entry interceptors: loggingZap: enabled: true------------------------------------------------------------------------ ... ids={"eventId":"cd617f0c-2d93-45e1-bef0-95c89972530d"} ...

RequestId

当启动了日志拦截器和原数据拦截器，RequestId 和 EventId 会自动生成，并且这两个 ID 会一致。

--- grpc: - name: greeter # Name of grpc entry port: 1949 # Port of grpc entry enabled: true # Enable grpc entry interceptors: loggingZap: enabled: true meta: enabled: true------------------------------------------------------------------------ ... ids={"eventId":"8226ba9b-424e-4e19-ba63-d37ca69028b3","requestId":"8226ba9b-424e-4e19-ba63-d37ca69028b3"} ...

即使用户覆盖了 RequestId，EventId 也会保持一致。

rkgrpcctx.AddHeaderToClient(ctx, rkgrpcctx.RequestIdKey, "overridden-request-id")------------------------------------------------------------------------ ... ids={"eventId":"overridden-request-id","requestId":"overridden-request-id"} ...

TraceId

当启动了调用链拦截器，traceId 会自动生成。

--- grpc: - name: greeter # Name of grpc entry port: 1949 # Port of grpc entry enabled: true # Enable grpc entry interceptors: loggingZap: enabled: true meta: enabled: true tracingTelemetry: enabled: true