feat: production server error handling

Author: rohitbytecode

server.js

@@ -1,14 +1,69 @@
 import 'dotenv/config';
+import http from 'http';
 import app from './src/app.js';
 import connectDB from './src/config/db.js';
+import { start } from 'repl';
 
 const PORT = process.env.PORT || 5000;
+const NODE_ENV = process.env.NODE_ENV || 'development';
 
-connectDB().then(() => {
-  app.listen(PORT, () => {
-    console.log(`Server running on port ${PORT}`);
-    console.log("Deployment");
-  });
-}).catch((error) => {
-  console.log(`Error: ${error}`);
+let server;
+
+const startServer = async() => {
+  try {
+    if (!process.env.MONGO_URI) {
+      throw new Error("MONGO_URI is missing in environment variables");
+    }
+
+    if (!process.env.JWT_SECRET) {
+      throw new Error("JWT_SECRET is missing in environment variables");
+    }
+
+    await connectDB();
+    console.log("DB connected successfully");
+
+    server = http.createServer(app);
+
+    server.listen(PORT, () => {
+      console.log(`Server running in ${NODE_ENV} mode on port ${PORT}`);
+    });
+  } catch(error) {
+    console.error("Startup error: ", error.message);
+    process.exit(1);
+  }
+};
+
+startServer();
+
+process.on("unhandledRejection", (err) => {
+  console.error("Unhandled Rejection: ", err);
+  shutdownGracefully();
 });
+
+process.on("uncaughtException", (err) => {
+  console.error("Uncaught Exception: ", err);
+  shutdownGracefully();
+});
+
+const shutdownGracefully = () => {
+  if (server) {
+    server.close(() => {
+      console.log("Server closed grecefully");
+      process.exit(1);
+    });
+  }
+  else {
+    process.exit(1);
+  }
+};
+
+process.on("SIGTERM", () => {
+  console.log("SIGTERM received. Shutting down...");
+  shutdownGracefully();
+});
+
+process.on("SIGINT", () => {
+  console.log("SIGINT reveiced. Shutting down...");
+  shutdownGracefully();
+});
+