configerator

Simple module for implementing environment based configuration following the The Twelve-factor App pattern.

This was adapted from the configuration implementation in Pliny.

Add this line to your application's Gemfile:

gem 'configerator'

And then execute:

$ bundle

Or install it yourself as:

$ gem install configerator

• required :key
  • Require a key, raise a KeyError if key is not supplied on application start up.
• required :key, error_on_load: false
  • Require a key, raise a RuntimeError if key is not supplied when key is requested.
• optional :key
  • Create key, set to nil if not present.
• override :key, :value
  • Create key, set to value if not present.
• namespace :name { optional :key }
  • Namespaces a collection of keys — e.g. name_key
  • Creates a validator for all defined keys in the block — e.g. name?
  • Skip prefixing namespace for variables and methods with prefix: false

# namespace example
namespace :aws do
  required :token,  string
  required :secret, string
  optional :region, string
end

# where
aws?

#=> true # if aws_token? && aws_secret? && aws_region?

# namespace without prefix
namespace :etc, prefix: false do
  required :foo, string
  required :bar, string
end

# where
etc?
#=> true # if foo? && bar?

You can generate a config file, thusly:

rails generate configerator:config

This will generate a configuration into config/config.rb with tips in comments.

Over time your config will be customized to your app, for example:

# file: config/config.rb
require 'configerator'

module Config
  extend Configerator

  required :something,    string
  optional :anotherthing, string
  override :port, 3000,   int
end

# file: config/application.rb
require_relative 'boot'
require 'rails/all'

# after to let rails framework to load first
require_relative 'config'

As a module

require 'configerator'

module Config
  extend Configerator

  required :something,    string
  optional :anotherthing, string
  override :port, 3000,   int
end

puts "#{Config.something}, and maybe: '#{Config.anotherthing}', all with #{Config.port}"

Included

require 'configerator'

class Foo
  include Configerator

  def initialize
    required :something,    string
    optional :anotherthing, string
    override :port, 3000,   int
  end

  def run
    puts "Doing %s with %s on %s" % [ something, anotherthing, port ]
  end
end

Configerator will autodetect Dotenv or dotenv-rails and load it so that its environment variables are available as soon as the Configerator is ready.

NOTE: For Rails projects, Configerator uses the dotenv-rails method to load your .env files. This may be of some surprise when it loads both your .env and .env.test configurations.

When dotenv-rails initializes, it loads environment files in this order:

• .env.local
• .env.$RAILS_ENV
• .env

We recommend that you use .env.development instead of .env for your development configurations and .env.test for your test configurations. One nice side effect is you will no longer have to Dotenv.load(".env.test") in your test_helper.rb/spec_helper.rb.

You would then use .env for shared configurations across all environments.

Of course if this doesn't work for your needs you can bypass autodetecting and loading of Dotenv. You can do this by requiring the library directly:

require 'configerator/configerator'

# w/ docker
$ docker-compose --rm test

# w/o docker
$ make

# w/o make and docker
$ bundle install
$ bundle exec ruby -Ilib:test ./test/*_test.rb