server.go

package strest

import (
	"context"
	"fmt"
	llog "log"
	"net/http"
	"sync/atomic"
)

type key int

const (
	requestIDKey key = 0
)

var (
	listenAddr string
	healthy    int32
)

func index() http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/" {
			http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
			return
		}
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		w.Header().Set("X-Content-Type-Options", "nosniff")
		w.WriteHeader(http.StatusOK)
		fmt.Fprintln(w, "Hello, World!")
	})
}
func userFunc() http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/user" {
			http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
			return
		}
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		w.Header().Set("X-Content-Type-Options", "nosniff")
		w.WriteHeader(http.StatusOK)
		fmt.Fprintln(w, "Hello, World!")
	})
}

func healthz() http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if atomic.LoadInt32(&healthy) == 1 {
			w.WriteHeader(http.StatusNoContent)
			return
		}
		w.WriteHeader(http.StatusServiceUnavailable)
	})
}

func logging(logger *llog.Logger) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			defer func() {
				requestID, ok := r.Context().Value(requestIDKey).(string)
				if !ok {
					requestID = "unknown"
				}
				logger.Println(requestID, r.Method, r.URL.Path, r.RemoteAddr, r.UserAgent())
			}()
			next.ServeHTTP(w, r)
		})
	}
}

func tracing(nextRequestID func() string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			requestID := r.Header.Get("X-Request-Id")
			if requestID == "" {
				requestID = nextRequestID()
			}
			ctx := context.WithValue(r.Context(), requestIDKey, requestID)
			w.Header().Set("X-Request-Id", requestID)
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}