Vercel Configuration for Typescript Express Servers

server.ts

import 'colors'
import { config } from 'dotenv'
import { createServer } from 'http'
import morgan from 'morgan'
import cors from 'cors'
import Express from 'express'
import BodyParser from 'body-parser'
import { testRoute } from 'api/route/test'

config()

process.env.TZ = 'America/New_York'

export const PORT = Number(process.env.PORT || '4242')

export const api = Express()
export const server = createServer(api)

api.use(cors())
api.use(BodyParser.json())
api.use(BodyParser.urlencoded({ extended: true }))
api.use(morgan('tiny'))

api.get('/', (req, res) => {
  return res.status(200).send('OK')
})

api.post('/test', testRoute)

module.exports = server

tsconfig.json

{
  "compilerOptions": {
    "target": "ES6",
    "lib": ["ESNext"],
    "baseUrl": "./",
    "allowJs": true,
    "skipLibCheck": true,
    "strict": false,
    "forceConsistentCasingInFileNames": true,
    "noEmit": true,
    "incremental": true,
    "esModuleInterop": true,
    "module": "CommonJS",
    "moduleResolution": "Node",
    "allowImportingTsExtensions": true,
    "resolveJsonModule": true,
    "isolatedModules": true,
    "composite": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "strictPropertyInitialization": false
  },
  "include": ["api/**/*.ts"],
  "exclude": ["node_modules"]
}

vercel.json

{
  "version": 2,
  "builds": [
    {
      "src": "api/server.ts",
      "use": "@vercel/node",
      "config": { "includeFiles": ["api/**"] }
    }
  ],
  "routes": [
    {
      "src": "/(.*)",
      "dest": "api/server.ts"
    }
  ]
}