op-service: Exit HTTP server more cleanly

op-service/httputil/server.go

@@ -2,13 +2,14 @@ package httputil
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/http"
 	"time"
 )
 
 func ListenAndServeContext(ctx context.Context, server *http.Server) error {
-	errCh := make(chan error)
+	errCh := make(chan error, 1)
 	go func() {
 		errCh <- server.ListenAndServe()
 	}()
@@ -22,6 +23,19 @@ func ListenAndServeContext(ctx context.Context, server *http.Server) error {
 		break
 	}
 
-	<-ctx.Done()
-	return ctx.Err()
+	select {
+	case err := <-errCh:
+		if errors.Is(err, http.ErrServerClosed) {
+			return nil
+		}
+		return err
+	case <-ctx.Done():
+		_ = server.Shutdown(context.Background())
+
+		err := ctx.Err()
+		if errors.Is(err, context.Canceled) {
+			return nil
+		}
+		return err
+	}
 }