Backend: handle interrupt signals.

backend/flowey.go

@@ -1,11 +1,14 @@
 package main
 
 import (
+	"context"
 	"errors"
+	"fmt"
 	"log"
 	"net"
 	"net/http"
 	"os"
+	"os/signal"
 )
 
 func run() error {
@@ -19,9 +22,27 @@ func run() error {
 		return err
 	}
 	log.Printf("listening at %v", address)
-	return server.Serve(listener)
+
+	sigint := make(chan os.Signal, 1)
+	signal.Notify(sigint, os.Interrupt)
+
+	errs := make(chan error, 1)
+	go func() {
+		errs <- server.Serve(listener)
+	}()
+
+	select {
+	case <-sigint:
+		fmt.Print("\rinterrupting...\n")
+	case err := <-errs:
+		log.Printf("failed to serve: %w", err)
+	}
+
+	return server.Shutdown(context.Background())
 }
 
 func main() {
-	log.Fatal(run())
+	if err := run(); err != nil {
+		log.Fatal(err)
+	}
 }