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CI/CD in Ruby with CircleCI

Run Ruby CI/CD in CircleCI with an encrypted .env.vault file

Find a complete code example on GitHub for this guide.

Initial setup

Create a build.rb file. It's a very simple build script that outputs 'Hello World'.

build.rb

# build.rb
puts "Hello #{ENV["HELLO"]}"

Create a Gemfile.

Gemfile

# frozen_string_literal: true

source "https://rubygems.org"

Run bundle install to generate the Gemfile.lock.

bundle install

Create a .circleci/config.yml file.

.circleci/config.yml

# .circleci/config.yml
version: 2.1
orbs:
  ruby: circleci/[email protected]
jobs:
  build:
    docker:
      - image: cimg/ruby:2.7.3
    steps:
      - checkout
      - ruby/install-deps
      - run:
          name: Ruby build
          command: ruby build.rb

Commit all that to code and push to GitHub. Then connect your GitHub repo to CircleCI.

app.circleci.com

app.circleci.com

Once pushed, the CircleCI build will say 'Hello ' as it doesn't have a way to access the environment variable yet. Let's do that next.

Install dotenv-vault

Install dotenv-vault.

bundle add dotenv-vault

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-vault along with bundler/setup.

build.rb

# build.rb
require "bundler/setup"
require "dotenv-vault/load"
puts "Hello #{ENV["HELLO"]}"

Try running it locally.

ruby build.rb
Hello World

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

That covers local simulation of the CI. Let's solve for the real CI environment next.

Build .env.vault

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

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

Use the UI to configure those secrets per environment.

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

# ci
DOTENV_VAULT_CI="x26PuIKQ/xZ5eKrYomKngM+dO/9v1vxhwslE/zjHdg3l+H6q6PheB5GVDVIbZg=="
DOTENV_VAULT_CI_VERSION=2

Set DOTENV_KEY

Fetch your CI DOTENV_KEY.

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

Set DOTENV_KEY on CircleCI.

app.circleci.com

Build CI

Commit those changes safely to code and rerun the build.

That's it! On rerun, your .env.vault file will be decrypted and its CI secrets injected as environment variables – just in time. It will say Hello ci.

app.circleci.com build

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.

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.