Check environment variable presence easily.

bundle install require_env

Create a YAML file, e.g. config/environment.yml, where you define the environment variables required by your application, for the different environment it will run (test, development, production by default)

• You can use ERB code to provide computed values
• You can use YAML defaults.
• An optional default value can be given for any key
• Keys ending with _IF_OTHER_VARIABLE will only be checked if OTHER_VARIABLE is defined and not equal 'false'
• Default value have precedence over the _IF_OTHER_VARIABLE rule

Here is an example presenting the different possibilities:

DEFAULTS: &DEFAULTS
  BEANSTALK_URL: 'beanstalk://127.0.0.1'

  SLACK_TOKEN:

  # Use the environment variable TOKEN_SCALINGO as a default value if provided
  SCALINGO_TOKEN: "<%= ENV['TOKEN_SCALINGO'] %>"

  # Declare STRIPE_ENABLED to check for STRIPE_PUBLIC_KEY and STRIPE_SECRET_KEY
  STRIPE_PUBLIC_KEY_IF_STRIPE_ENABLED:
  STRIPE_SECRET_KEY_IF_STRIPE_ENABLED:

test:
  <<: *DEFAULTS
  IGNORE_EVENT_DELAY: 'true'

development:
  <<: *DEFAULTS
  IGNORE_EVENT_DELAY: 'true'

production:
  <<: *DEFAULTS

When your application starts, simply call RequireEnv.check(Rails.root.join('config', 'environment.yml')) to check if the required environment variables are provided.

If any variable is missing, RequireEnv::Missing will be raised, detailing the missing environment variable.