middleware.go

package gateway

import (
	"context"
	"log"
	"net/http"
)

// tracing is a mw that wraps a handler, providing it with a requestID embeded in its context.
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(context.Background(), requestIDKey, requestID)
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}

// logging is a mw that wraps a handler enabling it logging on a route-basis.
func logging(logger *log.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)
		})
	}
}