Settei

Hash based configuration with flexibility and 12-factor app deployment in mind

Design Philosophies

  • Fast as it is accessible without loading Rails
  • Ease of management as nested hash is allowed
  • 12-factor compatible by serializing as environment variable.
  • Minimal meta-programming magics, so you can add your flavor of magic.

Installation

Add this line to your application's Gemfile:

gem 'settei'

And then execute:

$ bundle

Or install it yourself as:

$ gem install settei

Usage

For Rails, a rake task is available for simple setup:

$ settei:install:rails

A config/setting.rb file is added for basic setup.

YAML files are added under config/environments and is ignored by git.

In your app, you can access the settings like this:

Setting.dig(:google, :api, :secret)

Settei::Base

Settei::Base is the core class for accessing the configurations. It is initialized by a hash. It is a light wrapper intended for you to extend.

#dig is used to access its values. It's convenient because it does not err if nested hash is absent.

#dig_and_wrap will return a Settei::Base if it the return value is a hash.

Install script maps Setting to an instance of Settei::Base, for convenience.

Loader

Settei::Loaders::SimpleLoader is responsible for providing the hash to initialize Settei::Base. It loads from a source such as YAML or environment variable. It can also serialize the whole hash into one string, suitable for deploying via environment variables.

loader = Settei::Loaders::SimpleLoader.new(dir: 'path/to/dir')
loader.load.as_hash # loads default.yml and returns a hash
loader.load(:production).as_env_value # loads production.yml and returns "XYZ"
loader.load(:test).as_env_assignment # loads test.yml and returns "APP_CONG=XYZ"

We welcome PRs for different types of loaders, as SimpleLoader is not suitable for every situation.

Deployment

If deploy.rb is present, rake settei:install:rails will append code to it, allow serialized config to be passed as an environment variable.

Frameworks other than Rails

Settei is designed to be simple so you can integrate it into any frameworks easily. The steps are mainly:

  1. Designate a folder for storing YAML files.
  2. Create a setting.rb file, in which Settei::Base is initialized (see templates/setting.rb)
  3. Require it when framework starts.
  4. Load and pass serialized production config as environment variable in deploy script (see templates/_capistrano.rb or templates/_mina.rb).

We also welcome PRs for generators of other frameworks too.

Ruby < 2.3

Settei::Base uses dig to access the configuration, available since Ruby 2.3. If your Ruby is not new enough, don't be afraid. Write your own hash accessor literally takes minutes. You can even use SettingsLogic.new(hash) .

FAQ

Q: Would serialized configuration be too big for environment variable?
A: The upper limit is pretty big.

TODO

  • Integrate Rails configurations (e.g. database) into Settei.
  • Explore deep merge hash so development.yml can combine with default.yml.
  • Make loader configurable so it is easy to add and mix functionality.