Distributed Logging: ตอนที่ 1 ให้ Log รู้ว่าเกิดจาก Request เดียวกัน

project/ ├── cmd/ │ └── main.go ├── middleware/ │ └── request_context.go ├── handler/ │ └── user_handler.go ├── service/ │ └── user_service.go ├── repository/ │ └── user_repository.go ├── Dockerfile ├── docker-compose.yml ├── nginx.conf ├── go.mod └── go.sum 

http { server { listen 80; location / { # ถ้ามี X-Request-ID แล้ว ให้ใช้ของเดิม # ถ้าไม่มี ให้ generate ใหม่จาก $request_id ของ NGINX proxy_set_header X-Request-ID $request_id; proxy_pass http://backend; } } # ตั้ง backend upstream upstream backend { server app:3000; } } 

// ctxkey/ctxkey.go package ctxkey type key int const ( Logger key = iota RequestID ) 

// logger/logger.go package logger import ( "context" "demo-logger/ctxkey" "go.uber.org/zap" ) var baseLogger *zap.Logger func InitLogger() { l, _ := zap.NewProduction() baseLogger = l.With(zap.String("app_name", "demo-logger")) } func Default() *zap.Logger { return baseLogger } func Logger(ctx context.Context) *zap.Logger { log, ok := ctx.Value(ctxkey.Logger).(*zap.Logger) if ok { return log } return baseLogger } 

// middleware/request_context.go package middleware import ( "context" "demo-logger/ctxkey" "demo-logger/logger" "github.com/gofiber/fiber/v2" "github.com/google/uuid" "go.uber.org/zap" ) func RequestContext() fiber.Handler { return func(c *fiber.Ctx) error { reqID := c.Get("X-Request-ID") if reqID == "" { reqID = uuid.New().String() } // Bind Request ID ลง Response Header c.Set("X-Request-ID", reqID) // สร้าง child logger reqLogger := logger.Default().With(zap.String("request_id", reqID)) // สร้าง Context ใหม่ ctx := context.WithValue(c.Context(), ctxkey.RequestID, reqID) ctx = context.WithValue(ctx, ctxkey.Logger, reqLogger) // แทน Context เดิม c.SetUserContext(ctx) return c.Next() } } 

// handler/user_handler.go package handler import ( "demo-logger/logger" "demo-logger/service" "github.com/gofiber/fiber/v2" "go.uber.org/zap" ) type UserHandler struct { svc *service.UserService } func NewUserHandler(svc *service.UserService) *UserHandler { return &UserHandler{svc: svc} } func (h *UserHandler) GetUser(c *fiber.Ctx) error { userID := c.Params("id") // ใช้ UserContext() เพราะใส่ logger ไว้ที่นี่ user, err := h.svc.GetUser(c.UserContext(), userID) if err != nil { // ดึง logger จาก context logger.FromContext(c.UserContext()).Error("failed to get user") return c.Status(fiber.StatusInternalServerError).SendString("error") } // ดึง logger จาก context logger.FromContext(c.UserContext()).Info("success get user", zap.String("user_id", userID)) return c.JSON(user) } 

// service/user_service.go package service import ( "context" "demo-logger/logger" "demo-logger/repository" "go.uber.org/zap" ) type UserService struct { repo *repository.UserRepository } func NewUserService(repo *repository.UserRepository) *UserService { return &UserService{repo: repo} } func (s *UserService) GetUser(ctx context.Context, userID string) (any, error) { // ดึง logger จาก context logger.FromContext(ctx).Info("calling repo", zap.String("user_id", userID)) return s.repo.FindByID(ctx, userID) } 

// repository/user_repository.go package repository import ( "context" "demo-logger/logger" "go.uber.org/zap" ) type UserRepository struct { // DB connection } func NewUserRepository() *UserRepository { return &UserRepository{} } func (r *UserRepository) FindByID(ctx context.Context, userID string) (any, error) { // ดึง logger จาก context logger.FromContext(ctx).Info("querying database", zap.String("user_id", userID)) // สมมติคืน mock user return map[string]string{"id": userID, "name": "ball"}, nil } 

// cmd/main.go package main import ( "demo-logger/handler" "demo-logger/logger" "demo-logger/middleware" "demo-logger/repository" "demo-logger/service" "github.com/gofiber/fiber/v2" ) func main() { logger.InitLogger() app := fiber.New() app.Use(middleware.RequestContext()) repo := repository.NewUserRepository() svc := service.NewUserService(repo) hdl := handler.NewUserHandler(svc) app.Get("/user/:id", hdl.GetUser) app.Listen(":3000") } 

# ---------- STAGE 1: Build ---------- FROM golang:1.24 AS builder # Set working dir WORKDIR /app # Copy go.mod and go.sum first for caching dependencies COPY go.mod go.sum ./ # Download dependencies RUN go mod download # Copy the source code COPY . . # Build binary - youสามารถเปลี่ยนชื่อได้ตามต้องการ RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o app ./cmd/main.go # ---------- STAGE 2: Run ---------- FROM alpine:latest # ทำให้ binary ทำงานได้ (สำหรับบาง lib เช่น timezone) RUN apk --no-cache add ca-certificates # Set working dir WORKDIR /root/ # Copy binary จาก builder stage COPY --from=builder /app/app . # Expose port (ถ้ามี) EXPOSE 3000 # Command to run CMD ["./app"] 

services: nginx: image: nginx:latest container_name: nginx-proxy ports: - "80:80" volumes: - ./nginx.conf:/etc/nginx/nginx.conf:ro depends_on: - app app: build: . container_name: backend-app 

docker compose up -d --build 

backend-app | {"level":"info","ts":1751602673.5724216,"caller":"service/user_service.go:20","msg":"calling repo","app_name":"demo-logger","request_id":"29988fdef291b7afaadaa872cea0d5ba","user_id":"1"} backend-app | {"level":"info","ts":1751602673.5769289,"caller":"repository/user_repository.go:19","msg":"querying database","app_name":"demo-logger","request_id":"29988fdef291b7afaadaa872cea0d5ba","user_id":"1"} backend-app | {"level":"info","ts":1751602673.5770924,"caller":"handler/user_handler.go:28","msg":"success get user","app_name":"demo-logger","request_id":"29988fdef291b7afaadaa872cea0d5ba","user_id":"1"}