Enable nest start script to be run as well as serverless offline

package.json

@@ -8,9 +8,10 @@
     "packageManager": "yarn@3.4.1",
     "scripts": {
         "build": "nest build --webpack",
-        "deploy": "yarn build && cross-env NODE_ENV=production serverless deploy",
+        "deploy": "yarn build && cross-env NODE_ENV=production DEPLOYMENT_ENV=serverless serverless deploy",
         "format": "prettier --write \"src/**/*.ts\" \"test/**/*.ts\"",
-        "start": "yarn build && cross-env NODE_ENV=development serverless offline",
+        "start": "nest start --watch",
+        "start:serverless": "yarn build && cross-env NODE_ENV=development DEPLOYMENT_ENV=serverless serverless offline",
         "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix",
         "test:watch": "jest --watch",
         "test:cov": "jest --coverage",

serverless.yml

@@ -10,6 +10,7 @@ provider:
     environment:
         DATABASE_URL: ${env:DATABASE_URL}
         NODE_ENV: ${env:NODE_ENV}
+        DEPLOYMENT_ENV: ${env:DEPLOYMENT_ENV}
 
 useDotenv: true
 

src/consts.ts

@@ -6,3 +6,6 @@ export const SITE_TITLE = "Ergast API";
 export const SITE_DESCRIPTION =
     "The Ergast API provides a historical record of motor racing data for non-commercial purposes. The API provides data for the Formula One series, from the beginning of the world championships in 1950.";
 export const API_VERSION = "1.0";
+
+export const isProduction = process.env.NODE_ENV === "production";
+export const isServerless = process.env.DEPLOYMENT_ENV === "serverless";

src/getApp.ts

@@ -0,0 +1,12 @@
+import { NestFactory } from "@nestjs/core";
+import { AppModule } from "./app.module";
+import mainConfig from "./main.config";
+import setupSwagger from "./setupSwagger";
+
+export default async function getApp() {
+    const app = await NestFactory.create(AppModule);
+    mainConfig(app);
+    setupSwagger(app);
+
+    return app;
+}

src/main.serverless.ts

@@ -0,0 +1,17 @@
+import serverlessExpress from "@vendia/serverless-express";
+import { Callback, Context, Handler } from "aws-lambda";
+import getApp from "./getApp";
+
+let server: Handler;
+async function bootstrapServerLess(): Promise<Handler> {
+    const app = await getApp();
+    await app.init();
+
+    const expressApp = app.getHttpAdapter().getInstance();
+    return serverlessExpress({ app: expressApp });
+}
+
+export const handler: Handler = async (event: any, context: Context, callback: Callback) => {
+    server = server ?? (await bootstrapServerLess());
+    return server(event, context, callback);
+};

src/main.ts

@@ -1,24 +1,10 @@
-import { NestFactory } from "@nestjs/core";
-import serverlessExpress from "@vendia/serverless-express";
-import { Callback, Context, Handler } from "aws-lambda";
-import { AppModule } from "./app.module";
-import mainConfig from "./main.config";
-import setupSwagger from "./setupSwagger";
+import { API_PORT } from "./consts";
+import getApp from "./getApp";
 
-let server: Handler;
-
-async function bootstrap(): Promise<Handler> {
-    const app = await NestFactory.create(AppModule);
-
-    mainConfig(app);
-    setupSwagger(app);
-    await app.init();
-
-    const expressApp = app.getHttpAdapter().getInstance();
-    return serverlessExpress({ app: expressApp });
+async function bootstrap() {
+    const app = await getApp();
+    console.log(`Server is listening on port ${API_PORT}\n`);
+    await app.listen(API_PORT);
 }
 
-export const handler: Handler = async (event: any, context: Context, callback: Callback) => {
-    server = server ?? (await bootstrap());
-    return server(event, context, callback);
-};
+bootstrap();

src/setupSwagger.ts

@@ -1,6 +1,6 @@
 import { INestApplication } from "@nestjs/common";
 import { SwaggerModule, DocumentBuilder } from "@nestjs/swagger";
-import { API_VERSION, SITE_DESCRIPTION, SITE_TITLE } from "./consts";
+import { API_VERSION, SITE_DESCRIPTION, SITE_TITLE, isProduction, isServerless } from "./consts";
 
 export default function setupSwagger(app: INestApplication) {
     const config = new DocumentBuilder()
@@ -10,7 +10,14 @@ export default function setupSwagger(app: INestApplication) {
         .build();
     const document = SwaggerModule.createDocument(app, config);
 
-    const path = process.env.NODE_ENV === "production" ? "/" : "/docs";
+    const path = (() => {
+        if (isProduction || !isServerless) {
+            return "/";
+        }
+
+        return "/docs";
+    })();
+
     SwaggerModule.setup(path, app, document, {
         // explorer?: boolean;
         // swaggerOptions?: Record<string, any>;

webpack.config.js

@@ -11,6 +11,7 @@ module.exports = (options, webpack) => {
 
     return {
         ...options,
+        entry: "./src/main.serverless.ts",
         externals: [],
         optimization: {
             minimize: true,