sify21 · November 26, 2019 09:18 · Sep 11, 2017
diff --git a/middleware_full.go b/middleware_full.go
@@ -0,0 +1,55 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+)
+
+func init() {
+	log.SetFlags(log.Lshortfile)
+}
+
+// middleware provides a convenient mechanism for filtering HTTP requests
+// entering the application. It returns a new handler which performs various
+// operations and finishes with calling the next HTTP handler.
+type middleware func(http.HandlerFunc) http.HandlerFunc
+
+// chainMiddleware provides syntactic sugar to create a new middleware
+// which will be the result of chaining the ones received as parameters.
+func chainMiddleware(mw ...middleware) middleware {
+	return func(final http.HandlerFunc) http.HandlerFunc {
+		return func(w http.ResponseWriter, r *http.Request) {
+			last := final
+			for i := len(mw) - 1; i >= 0; i-- {
+				last = mw[i](last)
+			}
+			last(w, r)
+		}
+	}
+}
+
+func withLogging(next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		log.Printf("Logged connection from %s", r.RemoteAddr)
+		next.ServeHTTP(w, r)
+	}
+}
+
+func withTracing(next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		log.Printf("Tracing request for %s", r.RequestURI)
+		next.ServeHTTP(w, r)
+	}
+}
+
+func home(w http.ResponseWriter, r *http.Request) {
+	log.Println("reached home")
+	fmt.Fprintf(w, "welcome")
+}
+
+func main() {
+	mw := chainMiddleware(withLogging, withTracing)
+	http.Handle("/", mw(home))
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}