Vercel with Express

Learn how to make Vercel, Express, and Dotenv Vault work together. This tutorial assumes you have already created a .env file and synced it.

You can find a complete example repo here.

1. Set up Express for Vercel

Set up your Express app to work with Vercel. Add module.exports = app to index.js.

// index.js
const PORT = process.env.PORT || 5000
const express = require('express')
const app = express()

app.listen(PORT, () => {
  console.log(`Running on port ${PORT}.`)
})

app.get('/', (req, res) => {
  res.send(`Hello ${process.env.HELLO}`)
})

// Export the Express API for Vercel
module.exports = app

example

Add vercel.json file.

{
  "version": 2,
  "builds": [
    {
      "src": "index.js",
      "use": "@now/node"
    }
  ],
  "routes": [
    {
      "src": "/(.*)",
      "dest": "index.js"
    }
  ]
}

2. Require dotenv

Install dotenv.

npm install dotenv --save

Require it as early as possible in your Express application.

// index.js
require('dotenv').config()
console.log(process.env) // for debugging purposes. remove when ready.

const PORT = process.env.PORT || 5000
const express = require('express')
const app = express()
...

example

3. Run dotenv-vault build

Run npx dotenv-vault build to build your encrypted .env.vault file.

$ npx dotenv-vault build

4. Get DOTENV_KEY

Run npx dotenv-vault keys production.

$ npx dotenv-vault keys production
remote:   Listing .env.vault decryption keys... done

dotenv://:[email protected]/vault/.env.vault?environment=production

5. Set DOTENV_KEY

Visit your Vercel Project > Settings > Environment Variables.

Set DOTENV_KEY to the value returned in step 4.

6. Commit and push

That’s it!

Commit those changes safely to code and push to GitHub.

When the build runs, it will recognize the DOTENV_KEY, decrypt the .env.vault file, and load the production environment variables to ENV. If a DOTENV_KEY is not set (like during development on your local machine) it will fall back to regular dotenv.