Configru

YAML configuration file loader

Usage

Install the gem or add it to your Gemfile:

gem 'configru', '~> 3.6.0'

Next, require it and load a configuration:

require 'configru'

config = Configru::Config.new('config.yml')

This example loads config.yml if it exists. Or at least it would, if we told Configru the configuration options we wanted to load.

Options

Configru provides a DSL for specifying the options that should be loaded. The main method to specify configuration options is option.

config = Configru::Config.new('config.yml') do
  option :username, String, 'example_user', /^[A-Za-z1-9_]+$/
end

option takes 4 arguments: the configuration key, the type of value, the default value, and a validation check. The type defaults to Object, the default value defaults to nil and the validation check defaults to nothing. Note that a value of nil will be treated as the correct type regardless of the specified type.

The configuration option above can then be accessed in two ways:

config.username
config['username']

If the value in config.yml is not a String, a Configru::OptionTypeError will be raised. If the value does not pass the validation check, a Configru::OptionValidationError will be raised.

Validation

Validations are checked against the value of the option using the === operator. This allows validations to be Procs, Regexps and Ranges. If the validation is an Array, the value is checked using include?.

option can also be passed a block which can be used to set the validation for the option. This allows a more convenient way to write Proc validations.

config = Configru::Config.new('config.yml') do
  option :username, String, 'example_user' do
    validate {|o| o.length < 255 }
  end
end

Transformation

Configru also allows options to be transformed (using a Proc) as they are loaded.

config = Configru::Config.new('config.yml') do
  option :username, String, 'example' do
    transform {|o| o + '_user' }
  end
end

In the above example, if the username set in config.yml is "winnifred", it will be transformed using the Proc and config.username will be "winnifred_user".

Required options

For configuration options that have no default and must be set in the loaded configuration file, there is option_required. It takes the same arguments as option, except for a default value.

config = Configru::Config.new('config.yml') do
  option_required :username, String
end

If a required option is not set in the loaded file, a Configru::OptionRequiredError will be raised.

Array options

For options whose value should be a list, there is option_array. It takes the same arguments as option, except the default value is optional and defaults to an empty array. It behaves in the same way as option except each element of the array is checked against the type and the validation, and each element is transformed using the transformation Proc.

config = Configru::Config.new('config.yml') do
  option_array :users, String, ['user1', 'user2']
end

Boolean options

Since Ruby's true and false do not share a class such as Boolean, Configru provides a convenience method for boolean options, option_bool. It takes only an option key and a default value as arguments.

config = Configru::Config.new('config.yml') do
  option_bool :debug, false
end

The above example is equivalent to the following:

config = Configru::Config.new('config.yml') do
  option :debug, Object, false, [true, false]
end

(This works because Array validations are checked using include?)

Option groups

Configru allows nesting options in groups.

config = Configru::Config.new('config.yml') do
  option_group :user do
    option_required :name, String
    option_required :password, String
  end
end

The format for the configuration file would be:

user:
  name: example
  password: example

The above options can then be accessed using either method described above:

config.user.name
config.user.password
config['user']['name']
config['user']['password']

Option groups can, of course, be nested in other option groups.

Loading multiple files

Multiple files can be passed to Configru::Config.new and each will be loaded sequentially, replacing any values from previous files with new ones. This allows for loading a global configuration file and a user configuration file that can override the global configuration.

config = Configru::Config.new('/etc/config.yml', File.expand_path('~/config.yml')) do
  option :username, String, 'example_user'
end

Reloading

To reload configuration files, call the reload method on the Configru::Config object. Note that the entire DSL block will be re-evaluated.

config = Configru::Config.new('config.yml') do
  option :username, String, 'example_user'
end

config.reload

Global loading

Since it can be tedious to pass around the config object all over an application in order to have access to the configuration, the Configru module itself can be used as a Configru::Config object with the load method.

Configru.load('config.yml') do
  option :username, String, 'example_user'
end

Option values can then be accessed on the Configru module in the same way as on a Configru::Config object:

Configru.username
Configru['username']

The global configuration can also be reloaded in the same way:

Configru.reload

Access to the underlying Configru::Config object of the global configuration is provided:

Configru.config

License

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

programble/configru