Securely storing authentication keys

Many third-party APIs require a key, allowing them to prevent abuse. If they issue you a key, it's very important that you not commit the key into a public repository, as this will allow others to steal your key.

Storing authentication keys with Figaro

Add gem 'figaro' to your Gemfile and run bundle install. Then run bundle exec figaro install; this will create config/application.yml and add it to your .gitignore file, preventing it from being added to version control.

You can store your keys in application.yml in this format:

SECRET_NAME: secret_value

where SECRET_NAME and secret_value are the name and value of your API key.

You also need to name these secrets in config/secrets.yml. You can have different secrets in each environment. The file should look like this:

development:
  secret_name: <%= ENV["SECRET_NAME"] %>
test:
  secret_name: <%= ENV["SECRET_NAME"] %>
production:
  secret_name: <%= ENV["SECRET_NAME"] %>

How you use these keys varies, but say for example some_component in the development environment needs access to secret_name. In config/environments/development.rb, you'd put:

Rails.application.configure do
  config.some_component.configuration_hash = {
    :secret => Rails.application.secrets.secret_name
  }
end

Finally, let's say you want to spin up a production environment on Heroku. This command will upload the values in config/environments/production.rb to Heroku:

$ figaro heroku:set -e production