Leveraging Rails' custom configuration

Written by Jerome's Adventures in Software - - Aggregated on Saturday October 17, 2015

These days, I use environment variables for credentials and other sensitive data (secrets.yml could do the job but is too boilerplate-y for my taste). Dummy environment values are stored in my project dotenv file and production values are deployed to the PaaS server of my choice with a simple heroku config:set / eb setenv / etc.

But what about non-sensitive configuration values such as emails or your company address?

Storing them in environment variables both in your project and in your server is overkill and not really compliant with 12 factor apps. Those values are best stored in your project source code, in some sort of configuration file.

Rails 4.2 introduced a custom configuration object that can be accessed with Rails.configuration.x, and Rails.application.config_for loads YAML file values depending on the environment. By combining those two features, you can have all your custom configuration in a handy all-in-one YAML file!

Say your project is called MyApp:

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# MyApp custom configuration.
# Do not put sensitive data in this file (use environment variables instead).

default: &default
  emails:
    support: support@my-app.com
    marketing: marketing@my-app.com
  company_address: 221B Baker Street

production:
  <<: *default

development:
  <<: *default
  emails:
    support: support+dev@my-app.com

test:
  <<: *default
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# ...

module MyApp
  class Application < Rails::Application
    # ...

    # Custom configuration
    config.x = Hashie::Mash.new(Rails.application.config_for(:my_app))
  end
end

You can see that I wrap the loaded configuration hash in a hashie Mash object. I just use it for convenience so that I can access configuration variables with dots rather than brackets (it’s like OpenStruct with nested hash support). To use it, add gem 'hashie' to your Gemfile.

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Rails.configuration.x.emails.support

I hope that in future releases, Rails will improve its secret and configuration handling so that they can be even easier to use out of the box. But for now, this will do!


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