EnvConfig

Simple configuration management with environment variables.

Inspired by how Heroku uses environment variables for configs, EnvConfig is a no-magic gem for defining configs in yaml, and loading them into environment variables.

Features

• application.yml can be templated with erb.
• arbitrary namespaced configuration. e.g. development, qa:mac, integration/aws/ci.
• heroku friendly.
• small library, no additional dependencies

Installation

Install the gem, and initialize the configuation yaml and configuration loader.

gem install env_config

# if using Rails
rake env_config:init

# otherwise
env_config init

Example

First we define the configs we want in a yaml file:

# Each key value pair in this file will be read by EnvConfig and set to an
# environment variable. If an environment variable already exists, then it is
# not overridden by default. See EnvConfig.configure for more options.

# shared variables
common: &common
  env_config1: 'config1_value'
  env_config2: <%= "you can use erb" %>

# environment specifc variables
development:
  <<: *common
  env_config1: 'config1_override'

test:
  <<: *common

# If your app is deployed on Heroku, then production Heroku values will
# override these settings because existing variables are not overridden by
# default. See also: http://devcenter.heroku.com/articles/config-vars
production:
  <<: *common

Then in config/initializers/env_config.rb

EnvConfig.configure do |config|
  # yaml to read default config variables
  config.config_path   = 'config/application.yml'

  # Whether to override a variable that's already defined in an environment
  # variable. Keep to false if using Heroku.
  config.override_env  = false

  # Namespace config values
  # For example, to namespace by platform and rails environment
  # 
  #   config.namespace_by = "{RbConfig::CONFIG['host_os']}/#{Rails.env}"
  #
  # Then in your config/application.yml, you can nest your config by the
  # namepaces.
  # 
  #   darwin11.0.0:
  #     development:
  #       var_name: "mac development specific value"
  # 
  config.namespace_by  = Rails.env

  # Delimiter to split namespaces by when finding scoped config
  config.namespace_delimiter = '/'
end

# This actually sets the variables into ENV
EnvConfig.set!

From here, you can access any of your variables via ENV:

ENV['my_config_name']