feat: Added chapter 2

main.go

@@ -2,18 +2,27 @@ package main
 
 import (
 	"net/http"
+	"sync/atomic"
 )
 
+type apiConfig struct {
+	fileserverHits atomic.Int32
+}
+
 func main() {
+	apiCfg := &apiConfig{}
 	mux := http.NewServeMux()
 	fileServer := http.FileServer(http.Dir("."))
-	mux.Handle("/app", http.StripPrefix("/app", fileServer))
+	mux.Handle("/app", apiCfg.middlewareMetricsInc(http.StripPrefix("/app", fileServer)))
 	mux.Handle("/app/assets/", http.StripPrefix("/app/assets/", http.FileServer(http.Dir("./assets/"))))
-	mux.HandleFunc("/healthz", func(w http.ResponseWriter, req *http.Request) {
+	mux.HandleFunc("GET /healthz", func(w http.ResponseWriter, req *http.Request) {
 		req.Header.Set("Content-Type", "text/plain; charset=utf-8")
 		w.WriteHeader(http.StatusOK)
 		w.Write([]byte("OK"))
 	})
+	mux.Handle("GET /metrics", http.HandlerFunc(apiCfg.serveMetrics))
+	mux.Handle("POST /reset", http.HandlerFunc(apiCfg.serveReset))
+
 	server := &http.Server{
 		Addr:    ":8080",
 		Handler: mux,

metrics.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func (cfg *apiConfig) middlewareMetricsInc(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		cfg.fileserverHits.Add(1)
+		next.ServeHTTP(w, req)
+	})
+}
+
+func (cfg *apiConfig) serveMetrics(w http.ResponseWriter, r *http.Request) {
+	hits := cfg.fileserverHits.Load()
+	fmt.Fprintf(w, "Hits: %d", hits)
+}

reset.go

@@ -0,0 +1,9 @@
+package main
+
+import (
+	"net/http"
+)
+
+func (cfg *apiConfig) serveReset(w http.ResponseWriter, r *http.Request) {
+	cfg.fileserverHits.Store(0)
+}