Add interrupt signal handling for graceful server shutdown

backend/src/app.ts

@@ -28,8 +28,24 @@ app.use((err, req: Request, res: Response, next: NextFunction) => {
 nodesched.scheduleJob('regenerate data', '*/30 * * * * *', wxService.wrappedGenerateData)
 wxService.wrappedGenerateData();
 
-app.listen(PORT, () => {
+const server = app.listen(PORT, () => {
   console.log(
     `application is listening on port ${PORT}`,
   );
 });
+
+const shutdown = (signal: string) => {
+  console.log(`${signal} signal received. Shutting down.`);
+  server.close((err) => {
+    if (err) {
+      console.error(`Failed to shut down server gracefully: ${err}`);
+      process.exit(1);
+    }
+
+    console.log('Server closed');
+    process.exit(0);
+  });
+};
+
+process.on('SIGTERM', () => shutdown('SIGTERM'));
+process.on('SIGINT', () => shutdown('SIGINT'));