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Anyway Config

Rails/Ruby plugin/application configuration tool which allows you to load parameters from different sources: YAML, Rails secrets, environment.

Allows you to easily follow the twelve-factor application principles and adds zero complexity to your development process.

Libraries using Anyway Config:


1) Adding to a gem:

# my-cool-gem.gemspec do |spec|
  spec.add_dependency "anyway_config", "~> 1.0"

2) Adding to your project:

# Gemfile
gem "anyway_config", "~> 1.0"

3) Install globally:

$ gem install anyway_config


Pre-defined configuration

Create configuration class:

require 'anyway'

module MyCoolGem
  class Config < Anyway::Config
    attr_config user: 'root', password: 'root', host: 'localhost'

attr_config creates accessors and default values. If you don't need default values just write:

attr_config :user, :password, host: 'localhost'

Then create an instance of the config class and use it:

module MyCoolGem
  def self.config
    @config ||=

MyCoolGem.config.user #=> 'root'

Customize name

By default, Anyway Config uses the namespace (the outer module name) as the config name, but you can set it manually:

module MyCoolGem
  class Config < Anyway::Config
    config_name :cool
    attr_config user: 'root', password: 'root', host: 'localhost', options: {}

Customize env variable names prefix

By default, Anyway Config will use config name with stripped underscores as a prefix for env variable names (e.g. config_name :my_app will result to parsing MYAPP_HOST variable, not MY_APP_HOST). You can set env prefix explicitly, and it will be used as is:

module MyCoolGem
  class Config < Anyway::Config
    config_name :cool_gem
    env_prefix :really_cool # now variables, starting wih `REALLY_COOL_`, will be parsed
    attr_config user: 'root', password: 'root', host: 'localhost', options: {}

DEPRECATION WARNING In the 1.4 version no stripping will be applied on config_names by default, so if you use explicit config names with underscores and use env variables, your app will be broken. In this case it is recommended to start using env_prefix now.

Provide explicit values

Sometimes it's useful to set some parameters explicitly during config initialization. You can do that using overrides option:

config =
  overrides: {
    user: 'john',
    password: 'rubyisnotdead'

# The value would not be overriden from other sources (such as YML file, env)
config.user == 'john'

Dynamic configuration

You can also create configuration objects without pre-defined schema (just like Rails.application.config_for but more powerful):

# load data from config/my_app.yml, secrets.my_app (if using Rails), ENV["MYAPP_*"]
config = Anyway::Config.for(:my_app)

Using with Rails

Your config will be filled up with values from the following sources (ordered by priority from low to high):

  • RAILS_ROOT/config/my_cool_gem.yml (for the current RAILS_ENV, supports ERB)

  • Rails.application.secrets.my_cool_gem


Using with Ruby

By default, Anyway Config is looking for a config YAML at ./config/<config-name>.yml. You can override this setting through special environment variable – 'MYGEM_CONF' – containing the path to the YAML file.

Environmental variables work the same way as with Rails.

Config clear and reload

There are #clear and #reload functions on your config (which do exactly what they state).

Note: #reload also accepts overrides key to provide explicit values (see above).

Rails.application.config_for vs Anyway::Config.for

Rails 4.2 introduced new feature: Rails.application.config_for. It looks very similar to Anyway::Config.for, but there are some differences:

Feature Rails Anyway Config
load data from config/app.yml yes yes
load data from secrets no yes
load data from environment no yes
return Hash with indifferent access no yes
support ERB within config/app.yml yes yes*
raise errors if file doesn't exist yes no

*make sure that ERB is loaded

But the main advantage of Anyway::Config is that it can be used without Rails!)

How to set env vars

Environmental variables for your config should start with your config name, uppercased and underscore-free.

For example, if your module is called "MyCoolGem" then the env var "MYCOOLGEM_PASSWORD" is used as config.password.

Environment variables are type-casted (case-insensitive).


  • "True", "t" and "yes" to true;

  • "False", "f" and "no" to false;

  • "nil" and "null" to nil (do you really need it?);

  • "123" to 123 and "3.14" to 3.14.

Anyway Config supports nested (hashed) env variables. Just separate keys with double-underscore. For example, "MYCOOLGEM_OPTIONS__VERBOSE" is parsed as config.options["verbose"].

Array values are also supported:

# Suppose ENV["MYCOOLGEM_IDS"] = '1,2,3'
config.ids #=> [1,2,3]

If you want to provide a text-like env variable which contains commas then wrap it into quotes:

MYCOOLGEM="Nif-Nif, Naf-Naf and Nouf-Nouf"


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request