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Deploy a PM2 App to Heroku

Deploy a PM2 app with an encrypted .env.vault file to Heroku.

Find a complete code example on GitHub for this guide.

Initial setup

Generate an ecosystem.config.js file.

pm2 init

Modify it to your needs. Something like this.

ecosystem.config.js

module.exports = {
  apps : [{
    script: 'index.js',
    watch: '.'
  }]
};

Your index.js file should look something like this.

index.js

// index.js
const PORT = process.env.PORT || 3000
const http = require('http')
const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end(`Hello ${process.env.HELLO}`)
});

server.listen(PORT, () => {
  console.log(`Server running on port:${PORT}/`);
});

Add pm2 as a dependency.

npm install pm2 --save

In your package.json, modify your start script.

package.json

{
  "scripts": {
    "start": "pm2-runtime start ecosystem.config.js --env production"
  },
  "dependencies": {
    "pm2": "^5.3.0"
  }
}

Commit that to code and push it to Heroku.

heroku create
git push heroku
yourapp.herokuapp.com

Once deployed, your app will say 'Hello undefined' as it doesn't have a way to access the environment variable yet. Let's do that next.

Install dotenv

Install dotenv.

npm install dotenv --save # Requires dotenv >= 16.1.0

Create a .env file in the root of your project.

.env

# .env
HELLO="World"

As early as possible in your application, import and configure dotenv.

index.js

// index.js
require('dotenv').config()
console.log(process.env) // remove this after you've confirmed it is working

const PORT = process.env.PORT || 3000
const http = require('http')
...

Try running it locally.

pm2 start
➜  pm2-example git:(master) ✗ pm2 start
[PM2] Applying action restartProcessId on app [index](ids: [ 1 ])
[PM2] [index](1) ✓
┌────┬────────────────────┬──────────┬──────┬───────────┬──────────┬──────────┐
│ id │ name               │ mode     │ ↺    │ status    │ cpu      │ memory   │
├────┼────────────────────┼──────────┼──────┼───────────┼──────────┼──────────┤
│ 0  │ index              │ fork     │ 0    │ online    │ 0%       │ 1.2mb    │
└────┴────────────────────┴──────────┴──────┴───────────┴──────────┴──────────┘

Visit localhost:3000

It should say Hello World.

Great! process.env now has the keys and values you defined in your .env file. That covers local development. Let's solve for production next.

Build .env.vault

Push your latest .env file changes and edit your production secrets. Learn more about syncing

npx dotenv-vault@latest push
npx dotenv-vault@latest open production

Use the UI to configure those secrets per environment.

www.dotenv.org

Then build your encrypted .env.vault file.

npx dotenv-vault@latest build

Its contents should look something like this.

.env.vault

#/-------------------.env.vault---------------------/
#/         cloud-agnostic vaulting standard         /
#/   [how it works](https://dotenv.org/env-vault)   /
#/--------------------------------------------------/

# development
DOTENV_VAULT_DEVELOPMENT="/HqNgQWsf6Oh6XB9pI/CGkdgCe6d4/vWZHgP50RRoDTzkzPQk/xOaQs="
DOTENV_VAULT_DEVELOPMENT_VERSION=2

# production
DOTENV_VAULT_PRODUCTION="x26PuIKQ/xZ5eKrYomKngM+dO/9v1vxhwslE/zjHdg3l+H6q6PheB5GVDVIbZg=="
DOTENV_VAULT_PRODUCTION_VERSION=2

Set DOTENV_KEY

Fetch your production DOTENV_KEY.

npx dotenv-vault@latest keys production
# outputs: dotenv://:[email protected]/vault/.env.vault?environment=production

Set DOTENV_KEY on Heroku using the CLI.

heroku config:set DOTENV_KEY='dotenv://:key_1234…@dotenv.org/vault/.env.vault?environment=production'

Or use Heroku's UI.

www.heroku.com

Deploy

Commit those changes safely to code and deploy.

That's it! On deploy, your .env.vault file will be decrypted and its production secrets injected as environment variables – just in time.

You'll know things worked correctly when you see 'Loading env from encrypted .env.vault' in your logs. If a DOTENV_KEY is not set (for example when developing on your local machine) it will fall back to standard dotenv functionality.

heroku logs --tail

You succesfully used the new .env.vault standard to encrypt and deploy your secrets. This is much safer than scattering your secrets across multiple third-party platforms and tools. Whenever you need to add or change a secret, just rebuild your .env.vault file and redeploy.