Add graceful shutdown option to webserver

main.go

@@ -1,14 +1,41 @@
 package main
 
 import (
+	"context"
 	"gitlab.hpi.de/codeocean/codemoon/coolcodeoceannomadmiddleware/api"
 	"log"
 	"net/http"
+	"os"
+	"os/signal"
+	"time"
 )
 
 func main() {
-	err := http.ListenAndServe("0.0.0.0:4000", api.NewRouter())
-	if err != nil {
+	server := &http.Server{
+		Addr:         "0.0.0.0:4000",
+		WriteTimeout: time.Second * 15,
+		ReadTimeout:  time.Second * 15,
+		IdleTimeout:  time.Second * 60,
+		Handler:      api.NewRouter(),
+	}
+	go func() {
+		if err := server.ListenAndServe(); err != nil {
+			if err == http.ErrServerClosed {
+				log.Println(err)
+			} else {
 				log.Fatal("Error during listening and serving: ", err)
 			}
+		}
+	}()
+
+	// wait for SIGINT
+	signals := make(chan os.Signal, 1)
+	signal.Notify(signals, os.Interrupt)
+	<-signals
+	log.Println("Received SIGINT, shutting down ...")
+
+	// shutdown the server but wait up to 15 seconds to close remaining connections
+	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+	defer cancel()
+	_ = server.Shutdown(ctx)
 }