Go Chi Project Starter

mkdir -p myapp && cd myapp
go mod init github.com/yourorg/myapp
go get github.com/go-chi/chi/v5@latest
go get github.com/go-chi/render@latest
go get github.com/go-chi/cors@latest
go get github.com/jmoiron/sqlx@latest
go get github.com/lib/pq@latest
go get github.com/golang-jwt/jwt/v5@latest
go get github.com/go-playground/validator/v10@latest

myapp/
├── cmd/
│   └── server/
│       └── main.go              # Entrypoint, wires everything
├── internal/
│   ├── config/
│   │   └── config.go            # Env-based config
│   ├── handler/
│   │   ├── user.go              # User HTTP handlers
│   │   ├── auth.go              # Auth handlers
│   │   └── health.go            # Health check
│   ├── middleware/
│   │   ├── auth.go              # JWT auth middleware
│   │   └── logging.go           # Request logging with slog
│   ├── model/
│   │   └── user.go              # Domain models with DB tags
│   ├── repository/
│   │   └── user.go              # SQLX-based data access
│   ├── service/
│   │   └── user.go              # Business logic
│   └── server/
│       └── server.go            # Chi router setup, routes, middleware
├── migrations/
│   ├── 000001_create_users.up.sql
│   └── 000001_create_users.down.sql
├── pkg/
│   └── response/
│       └── response.go          # Shared JSON response helpers
├── docs/                        # Generated by swag init
├── .env.example                   # Environment variable template
├── go.mod
├── go.sum
└── Makefile

// cmd/server/main.go
package main

import (
	"context"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/jmoiron/sqlx"
	_ "github.com/lib/pq"

	"github.com/yourorg/myapp/internal/config"
	"github.com/yourorg/myapp/internal/server"
)

// @title           MyApp API
// @version         1.0
// @description     A sample Chi API server.
// @host            localhost:8080
// @BasePath        /api/v1
func main() {
	cfg := config.Load()

	// Structured logger
	logger := slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
		Level: slog.LevelInfo,
	}))
	slog.SetDefault(logger)

	// Database
	db, err := sqlx.Connect("postgres", cfg.DatabaseURL)
	if err != nil {
		slog.Error("database connection failed", "error", err)
		os.Exit(1)
	}
	defer db.Close()
	db.SetMaxOpenConns(25)
	db.SetMaxIdleConns(5)

	// Router
	router := server.NewRouter(cfg, db, logger)

	srv := &http.Server{
		Addr:         ":" + cfg.Port,
		Handler:      router,
		ReadTimeout:  10 * time.Second,
		WriteTimeout: 10 * time.Second,
		IdleTimeout:  60 * time.Second,
	}

	go func() {
		slog.Info("server starting", "port", cfg.Port)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			slog.Error("listen failed", "error", err)
			os.Exit(1)
		}
	}()

	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
	<-quit

	slog.Info("shutting down server...")
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	if err := srv.Shutdown(ctx); err != nil {
		slog.Error("forced shutdown", "error", err)
	}
	slog.Info("server exited")
}

// internal/server/server.go
package server

import (
	"log/slog"
	"net/http"
	"time"

	"github.com/go-chi/chi/v5"
	chiMiddleware "github.com/go-chi/chi/v5/middleware"
	"github.com/go-chi/cors"
	"github.com/jmoiron/sqlx"

	"github.com/yourorg/myapp/internal/config"
	"github.com/yourorg/myapp/internal/handler"
	appMiddleware "github.com/yourorg/myapp/internal/middleware"
	"github.com/yourorg/myapp/internal/repository"
	"github.com/yourorg/myapp/internal/service"
)

func NewRouter(cfg *config.Config, db *sqlx.DB, logger *slog.Logger) http.Handler {
	r := chi.NewRouter()

	// Middleware stack (order matters)
	r.Use(chiMiddleware.RequestID)
	r.Use(chiMiddleware.RealIP)
	r.Use(appMiddleware.StructuredLogger(logger))
	r.Use(chiMiddleware.Recoverer)
	r.Use(chiMiddleware.Timeout(30 * time.Second))
	r.Use(cors.Handler(cors.Options{
		AllowedOrigins:   cfg.AllowedOrigins,
		AllowedMethods:   []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"},
		AllowedHeaders:   []string{"Accept", "Authorization", "Content-Type"},
		AllowCredentials: true,
		MaxAge:           300,
	}))

	// Wire dependencies
	userRepo := repository.NewUserRepository(db)
	userSvc := service.NewUserService(userRepo)

	// Health check
	r.Get("/healthz", handler.Healthz)

	// API v1
	r.Route("/api/v1", func(r chi.Router) {
		// Public auth routes
		r.Route("/auth", func(r chi.Router) {
			r.Post("/login", handler.Login(userSvc, cfg))
			r.Post("/register", handler.Register(userSvc))
		})

		// Protected routes
		r.Group(func(r chi.Router) {
			r.Use(appMiddleware.AuthRequired(cfg.JWTSecret))

			r.Route("/users", func(r chi.Router) {
				r.Get("/", handler.ListUsers(userSvc))
				r.Post("/", handler.CreateUser(userSvc))

				// Subrouter with {id} param
				r.Route("/{id}", func(r chi.Router) {
					r.Get("/", handler.GetUser(userSvc))
					r.Put("/", handler.UpdateUser(userSvc))
					r.Delete("/", handler.DeleteUser(userSvc))
				})
			})
		})
	})

	return r
}

// internal/handler/user.go
package handler

import (
	"encoding/json"
	"errors"
	"log/slog"
	"net/http"
	"strconv"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/render"
	"github.com/go-playground/validator/v10"

	"github.com/yourorg/myapp/internal/service"
	"github.com/yourorg/myapp/pkg/response"
)

var validate = validator.New()

type CreateUserRequest struct {
	Name  string `json:"name"  validate:"required,min=2,max=100"`
	Email string `json:"email" validate:"required,email"`
	Age   int    `json:"age"   validate:"required,gte=1,lte=150"`
}

type UpdateUserRequest struct {
	Name string `json:"name" validate:"omitempty,min=2,max=100"`
	Age  int    `json:"age"  validate:"omitempty,gte=1,lte=150"`
}

// GetUser returns a handler that gets a user by ID.
// Dependencies are injected via closure -- no global state.
func GetUser(svc service.UserService) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		idStr := chi.URLParam(r, "id")
		id, err := strconv.ParseUint(idStr, 10, 64)
		if err != nil {
			response.Error(w, r, http.StatusBadRequest, "invalid id parameter")
			return
		}

		user, err := svc.GetByID(r.Context(), uint(id))
		if err != nil {
			if errors.Is(err, service.ErrNotFound) {
				response.Error(w, r, http.StatusNotFound, "user not found")
				return
			}
			slog.ErrorContext(r.Context(), "failed to get user", "error", err, "id", id)
			response.Error(w, r, http.StatusInternalServerError, "internal error")
			return
		}

		render.Status(r, http.StatusOK)
		render.JSON(w, r, user)
	}
}

// ListUsers returns a handler that lists users with pagination.
func ListUsers(svc service.UserService) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		page, _ := strconv.Atoi(r.URL.Query().Get("page"))
		pageSize, _ := strconv.Atoi(r.URL.Query().Get("page_size"))

		if page < 1 {
			page = 1
		}
		if pageSize < 1 || pageSize > 100 {
			pageSize = 20
		}

		users, total, err := svc.List(r.Context(), page, pageSize)
		if err != nil {
			slog.ErrorContext(r.Context(), "failed to list users", "error", err)
			response.Error(w, r, http.StatusInternalServerError, "internal error")
			return
		}

		render.JSON(w, r, map[string]interface{}{
			"data":      users,
			"total":     total,
			"page":      page,
			"page_size": pageSize,
		})
	}
}

// CreateUser returns a handler that creates a new user.
func CreateUser(svc service.UserService) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var req CreateUserRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			response.Error(w, r, http.StatusBadRequest, "invalid request body")
			return
		}
		if err := validate.Struct(&req); err != nil {
			response.ValidationError(w, r, err)
			return
		}

		user, err := svc.Create(r.Context(), req.Name, req.Email, req.Age)
		if err != nil {
			if errors.Is(err, service.ErrDuplicateEmail) {
				response.Error(w, r, http.StatusConflict, "email already registered")
				return
			}
			slog.ErrorContext(r.Context(), "failed to create user", "error", err)
			response.Error(w, r, http.StatusInternalServerError, "internal error")
			return
		}

		render.Status(r, http.StatusCreated)
		render.JSON(w, r, user)
	}
}

// UpdateUser returns a handler that updates a user.
func UpdateUser(svc service.UserService) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		idStr := chi.URLParam(r, "id")
		id, err := strconv.ParseUint(idStr, 10, 64)
		if err != nil {
			response.Error(w, r, http.StatusBadRequest, "invalid id parameter")
			return
		}

		var req UpdateUserRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			response.Error(w, r, http.StatusBadRequest, "invalid request body")
			return
		}
		if err := validate.Struct(&req); err != nil {
			response.ValidationError(w, r, err)
			return
		}

		user, err := svc.Update(r.Context(), uint(id), req.Name, req.Age)
		if err != nil {
			if errors.Is(err, service.ErrNotFound) {
				response.Error(w, r, http.StatusNotFound, "user not found")
				return
			}
			slog.ErrorContext(r.Context(), "failed to update user", "error", err)
			response.Error(w, r, http.StatusInternalServerError, "internal error")
			return
		}

		render.JSON(w, r, user)
	}
}

// DeleteUser returns a handler that deletes a user.
func DeleteUser(svc service.UserService) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		idStr := chi.URLParam(r, "id")
		id, err := strconv.ParseUint(idStr, 10, 64)
		if err != nil {
			response.Error(w, r, http.StatusBadRequest, "invalid id parameter")
			return
		}

		if err := svc.Delete(r.Context(), uint(id)); err != nil {
			if errors.Is(err, service.ErrNotFound) {
				response.Error(w, r, http.StatusNotFound, "user not found")
				return
			}
			slog.ErrorContext(r.Context(), "failed to delete user", "error", err)
			response.Error(w, r, http.StatusInternalServerError, "internal error")
			return
		}

		w.WriteHeader(http.StatusNoContent)
	}
}

// Healthz is a simple health check handler.
func Healthz(w http.ResponseWriter, r *http.Request) {
	render.JSON(w, r, map[string]string{"status": "ok"})
}

// internal/middleware/logging.go
package middleware

import (
	"log/slog"
	"net/http"
	"time"

	chiMiddleware "github.com/go-chi/chi/v5/middleware"
)

func StructuredLogger(logger *slog.Logger) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			start := time.Now()

			ww := chiMiddleware.NewWrapResponseWriter(w, r.ProtoMajor)
			next.ServeHTTP(ww, r)

			logger.Info("request completed",
				"method", r.Method,
				"path", r.URL.Path,
				"status", ww.Status(),
				"bytes", ww.BytesWritten(),
				"duration_ms", time.Since(start).Milliseconds(),
				"request_id", chiMiddleware.GetReqID(r.Context()),
				"remote_addr", r.RemoteAddr,
			)
		})
	}
}

// internal/middleware/auth.go
package middleware

import (
	"context"
	"net/http"
	"strings"

	"github.com/go-chi/render"
	"github.com/golang-jwt/jwt/v5"
)

type contextKey string

const UserIDKey contextKey = "userID"

func AuthRequired(secret string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			header := r.Header.Get("Authorization")
			if header == "" {
				render.Status(r, http.StatusUnauthorized)
				render.JSON(w, r, map[string]string{"error": "missing authorization header"})
				return
			}

			parts := strings.SplitN(header, " ", 2)
			if len(parts) != 2 || parts[0] != "Bearer" {
				render.Status(r, http.StatusUnauthorized)
				render.JSON(w, r, map[string]string{"error": "invalid authorization format"})
				return
			}

			token, err := jwt.Parse(parts[1], func(t *jwt.Token) (interface{}, error) {
				if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
					return nil, jwt.ErrSignatureInvalid
				}
				return []byte(secret), nil
			})
			if err != nil || !token.Valid {
				render.Status(r, http.StatusUnauthorized)
				render.JSON(w, r, map[string]string{"error": "invalid token"})
				return
			}

			claims, ok := token.Claims.(jwt.MapClaims)
			if !ok {
				render.Status(r, http.StatusUnauthorized)
				render.JSON(w, r, map[string]string{"error": "invalid claims"})
				return
			}

			// Add user ID to context
			ctx := context.WithValue(r.Context(), UserIDKey, claims["sub"])
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}

// GetUserID extracts the user ID from context. Returns empty string if not found.
func GetUserID(ctx context.Context) string {
	id, _ := ctx.Value(UserIDKey).(string)
	return id
}

// pkg/response/response.go
package response

import (
	"net/http"

	"github.com/go-chi/render"
	"github.com/go-playground/validator/v10"
)

type ErrorBody struct {
	Error   string            `json:"error"`
	Details map[string]string `json:"details,omitempty"`
}

func Error(w http.ResponseWriter, r *http.Request, status int, message string) {
	render.Status(r, status)
	render.JSON(w, r, ErrorBody{Error: message})
}

func ValidationError(w http.ResponseWriter, r *http.Request, err error) {
	details := make(map[string]string)
	if ve, ok := err.(validator.ValidationErrors); ok {
		for _, e := range ve {
			details[e.Field()] = e.Tag() + " validation failed"
		}
	}
	render.Status(r, http.StatusBadRequest)
	render.JSON(w, r, ErrorBody{
		Error:   "validation failed",
		Details: details,
	})
}

// internal/repository/user.go
package repository

import (
	"context"
	"database/sql"
	"errors"

	"github.com/jmoiron/sqlx"

	"github.com/yourorg/myapp/internal/model"
)

var ErrNotFound = errors.New("record not found")

type UserRepository interface {
	Create(ctx context.Context, user *model.User) error
	GetByID(ctx context.Context, id uint) (*model.User, error)
	GetByEmail(ctx context.Context, email string) (*model.User, error)
	List(ctx context.Context, offset, limit int) ([]model.User, int64, error)
	Update(ctx context.Context, user *model.User) error
	Delete(ctx context.Context, id uint) error
}

type userRepository struct {
	db *sqlx.DB
}

func NewUserRepository(db *sqlx.DB) UserRepository {
	return &userRepository{db: db}
}

func (r *userRepository) Create(ctx context.Context, user *model.User) error {
	query := `INSERT INTO users (name, email, age, created_at, updated_at)
	           VALUES (:name, :email, :age, NOW(), NOW())
	           RETURNING id, created_at, updated_at`

	rows, err := r.db.NamedQueryContext(ctx, query, user)
	if err != nil {
		return err
	}
	defer rows.Close()

	if rows.Next() {
		return rows.StructScan(user)
	}
	return errors.New("insert returned no rows")
}

func (r *userRepository) GetByID(ctx context.Context, id uint) (*model.User, error) {
	var user model.User
	err := r.db.GetContext(ctx, &user, "SELECT * FROM users WHERE id = $1 AND deleted_at IS NULL", id)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	return &user, err
}

func (r *userRepository) GetByEmail(ctx context.Context, email string) (*model.User, error) {
	var user model.User
	err := r.db.GetContext(ctx, &user, "SELECT * FROM users WHERE email = $1 AND deleted_at IS NULL", email)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	return &user, err
}

func (r *userRepository) List(ctx context.Context, offset, limit int) ([]model.User, int64, error) {
	var total int64
	err := r.db.GetContext(ctx, &total, "SELECT COUNT(*) FROM users WHERE deleted_at IS NULL")
	if err != nil {
		return nil, 0, err
	}

	var users []model.User
	err = r.db.SelectContext(ctx, &users,
		"SELECT * FROM users WHERE deleted_at IS NULL ORDER BY id LIMIT $1 OFFSET $2",
		limit, offset,
	)
	return users, total, err
}

func (r *userRepository) Update(ctx context.Context, user *model.User) error {
	query := `UPDATE users SET name = :name, age = :age, updated_at = NOW()
	           WHERE id = :id AND deleted_at IS NULL`
	result, err := r.db.NamedExecContext(ctx, query, user)
	if err != nil {
		return err
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrNotFound
	}
	return nil
}

func (r *userRepository) Delete(ctx context.Context, id uint) error {
	result, err := r.db.ExecContext(ctx,
		"UPDATE users SET deleted_at = NOW() WHERE id = $1 AND deleted_at IS NULL", id)
	if err != nil {
		return err
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrNotFound
	}
	return nil
}

// internal/model/user.go
package model

import "time"

type User struct {
	ID        uint       `db:"id"         json:"id"`
	Name      string     `db:"name"       json:"name"`
	Email     string     `db:"email"      json:"email"`
	Age       int        `db:"age"        json:"age"`
	CreatedAt time.Time  `db:"created_at" json:"created_at"`
	UpdatedAt time.Time  `db:"updated_at" json:"updated_at"`
	DeletedAt *time.Time `db:"deleted_at" json:"-"`
}

-- migrations/000001_create_users.up.sql
CREATE TABLE IF NOT EXISTS users (
    id         BIGSERIAL PRIMARY KEY,
    name       VARCHAR(100)  NOT NULL,
    email      VARCHAR(255)  NOT NULL UNIQUE,
    age        INT           NOT NULL CHECK (age > 0),
    created_at TIMESTAMPTZ   NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ   NOT NULL DEFAULT NOW(),
    deleted_at TIMESTAMPTZ
);

CREATE INDEX idx_users_email ON users (email) WHERE deleted_at IS NULL;

-- migrations/000001_create_users.down.sql
DROP TABLE IF EXISTS users;

# Run the server
go run ./cmd/server

# Run tests
go test ./... -v -race -count=1

# Run tests with coverage
go test ./... -coverprofile=coverage.out && go tool cover -html=coverage.out

# Generate Swagger docs
swag init -g cmd/server/main.go -o docs

# Lint
golangci-lint run ./...

# Build binary
go build -o bin/server ./cmd/server

# Tidy dependencies
go mod tidy

# Format code
gofmt -w .

# Database migrations
migrate -path migrations -database "$DATABASE_URL" up
migrate -path migrations -database "$DATABASE_URL" down 1
migrate create -ext sql -dir migrations -seq create_orders