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Deploy a Node.js App with Docker

Deploy a Node.js app with an encrypted .env.vault file on Docker.

Find a complete code example on GitHub for this guide.

Initial setup

Create an index.js file, if you haven't already done so.

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 package.json file.

package.json

{
  "scripts": {
    "start": "node index.js"
  }
}

Add a Dockerfile.

Dockerfile

# Dockerfile
FROM node:16
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD node index.js

Commit that to code and build it locally with Docker.

docker build -t docker-nodejs . && docker run --rm -it -p 3000:3000 --init docker-nodejs
yourapp running on docker

Once built, your app will say 'Hello undefined' at localhost:3000 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 rebuilding it locally.

docker build -t docker-nodejs . && docker run --rm -it -p 3000:3000 --init docker-nodejs
{
  ...
  HELLO: 'World'
}
Server running on port:3000/

Perfect. process.env now has the keys and values you defined in your .env file.

localhost

That covers the local development build. 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 for Docker run.

docker build -t docker-nodejs . && docker run -e DOTENV_KEY="dotenv://:[email protected]/vault/.env.vault?environment=production" --rm -it -p 3000:3000 --init docker-nodejs

The important part here is the -e flag. See docker environment variables for more information.

Run Docker

Commit those changes safely to code and run on Docker.

That's it! On build and run, 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.

docker build -t && docker run -e

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.