(NOBIDS) gracefully shutdown frontend (#2929)

cmd/explorer/main.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/gob"
 	"encoding/hex"
+	"errors"
 	"flag"
 	"fmt"
 	"math/big"
@@ -58,6 +59,8 @@ func init() {
 	gob.Register(types.DataTableSaveState{})
 }
 
+var frontendHttpServer *http.Server
+
 func main() {
 	configPath := flag.String("config", "", "Path to the config file, if empty string defaults will be used")
 	versionFlag := flag.Bool("version", false, "Show version and exit")
@@ -639,17 +642,17 @@ func main() {
 		if utils.Config.Frontend.HttpIdleTimeout == 0 {
 			utils.Config.Frontend.HttpIdleTimeout = time.Minute
 		}
-		srv := &http.Server{
+		frontendHttpServer = &http.Server{
 			Addr:         cfg.Frontend.Server.Host + ":" + cfg.Frontend.Server.Port,
 			WriteTimeout: utils.Config.Frontend.HttpWriteTimeout,
 			ReadTimeout:  utils.Config.Frontend.HttpReadTimeout,
 			IdleTimeout:  utils.Config.Frontend.HttpIdleTimeout,
 			Handler:      n,
 		}
 
-		logrus.Printf("http server listening on %v", srv.Addr)
+		logrus.Printf("http server listening on %v", frontendHttpServer.Addr)
 		go func() {
-			if err := srv.ListenAndServe(); err != nil {
+			if err := frontendHttpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 				logrus.WithError(err).Fatal("Error serving frontend")
 			}
 		}()
@@ -670,5 +673,14 @@ func main() {
 
 	utils.WaitForCtrlC()
 
+	if frontendHttpServer != nil {
+		logrus.Infof("shutting down frontendHttpServer")
+		ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
+		defer cancel()
+		if err := frontendHttpServer.Shutdown(ctx); err != nil {
+			logrus.WithError(err).Error("error shutting down frontend server")
+		}
+	}
+
 	logrus.Println("exiting...")
 }

utils/utils.go

@@ -28,6 +28,7 @@ import (
 	"sort"
 	"strconv"
 	"strings"
+	"syscall"
 	"time"
 	"unicode/utf8"
 
@@ -395,7 +396,7 @@ func GWeiBytesToEther(gwei []byte) decimal.Decimal {
 // WaitForCtrlC will block/wait until a control-c is pressed
 func WaitForCtrlC() {
 	c := make(chan os.Signal, 1)
-	signal.Notify(c, os.Interrupt)
+	signal.Notify(c, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
 	<-c
 }