మినీ-ప్రాజెక్ట్: ఒక HTTP సర్వర్

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprintf(w, "hello %s", r.URL.Path[1:])
    })
    if err := http.ListenAndServe(":8080", nil); err != nil {
        panic(err)
    }
}

func(w http.ResponseWriter, r *http.Request)

func ping(w http.ResponseWriter, r *http.Request) {
    if r.Method != http.MethodGet {
        http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
        return
    }
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(http.StatusOK) // optional, defaults to 200
    fmt.Fprintln(w, `{"ok":true}`)
}

mux := http.NewServeMux()
mux.HandleFunc("GET /users/{id}", func(w http.ResponseWriter, r *http.Request) {
    id := r.PathValue("id")
    fmt.Fprintln(w, "user", id)
})
mux.HandleFunc("POST /users", createUser)

http.ListenAndServe(":8080", mux)

func logMW(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        start := time.Now()
        next.ServeHTTP(w, r)
        log.Printf("%s %s %s", r.Method, r.URL.Path, time.Since(start))
    })
}

http.ListenAndServe(":8080", logMW(mux))

srv := &http.Server{
    Addr:              ":8080",
    Handler:           mux,
    ReadHeaderTimeout: 5 * time.Second,
    ReadTimeout:       30 * time.Second,
    WriteTimeout:      30 * time.Second,
    IdleTimeout:       2 * time.Minute,
}
log.Fatal(srv.ListenAndServe())

ctx, stop := signal.NotifyContext(context.Background(),
    os.Interrupt, syscall.SIGTERM)
defer stop()

srv := &http.Server{Addr: ":8080", Handler: mux}
go func() {
    if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
        log.Fatal(err)
    }
}()

<-ctx.Done() // wait for the signal

shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
if err := srv.Shutdown(shutdownCtx); err != nil {
    log.Println("shutdown:", err)
}

type CreateUserReq struct {
    Name string `json:"name"`
}

func createUser(w http.ResponseWriter, r *http.Request) {
    var req CreateUserReq
    if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
        http.Error(w, err.Error(), http.StatusBadRequest)
        return
    }
    // ... use req.Name
    w.WriteHeader(http.StatusCreated)
}