EnvConfig

Safer and convenient access to ENV variables in production applications.

EnvConfig wraps ENV, and provides some nice helpers and extensions.

1. #fetch!

Works just like Hash#fetch (or ENV.fetch), but raises an exception in production when attempting to access the value, rather than using the fallback. This causes your application to blow up early with a clear error message when you forgot to add the ENV var, rather than failing later with an opaque error.

Example:

EnvConfig.fetch("HOST", "localhost") # => "localhost"

# With RAILS_ENV=production (or RACK_ENV)
EnvConfig.fetch("HOST", "localhost") # => ProductionKeyError: Environment Variable HOST is required

2. #fetch?

When using Rails, casts the value to a boolean, using the same cast helper as Params. So "f", "false", "0", etc all become false, anything else is true.

3. Extensions

Comes with optional helpers when running with Rails and/or Heroku. PRs welcomed for other environments.

EnvConfig.load_extensions :rails, :heroku

EnvConfig.heroku? # true when running in a Heroku Dyno

EnvConfig.dyno # Parses eg 'worker.1` into "worker"
EnvConfig.dyno.worker? # Also works

Installation

Add this line to your application's Gemfile:

gem 'env_config'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install env_config

Usage

In Rails, I like to create a separate config with custom extensions for my app:

# lib/env_config.rb
module MyAppEnvConfig
  def my_helper
    @my_value ||= ActiveSupport::StringInquirer.new(fetch('MY_VAR') { local? ? 'localhost' : 'myapp.com' })
  end
end

EnvConfig.register_extension(:my_app) do
  EnvConfig::Config.prepend MyAppEnvConfig
end

EnvConfig.load_extensions :rails, :my_app

Then this needs to be pulled in early in the application boot process. I like putting it in application.rb, right after the Bundler.require step.

# config/application.rb

# ...
Bundler.require(*Rails.groups)

# Add this right after Bundler
require_relative '../lib/env_config'

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/paul/env_config. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the EnvConfig project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.