Rails config_for: Secrets to Credentials

Rails 5.1 introduced the use of secrets for storing encrypted secrets in source control.

It also allowed plain environment specific settings storage making usage of secrets.yml.

 # config/secrets.yml
 shared:
   mailer_default_from_email: "'Example' <[email protected]>"
   support_email: [email protected]
   mailer_delivery_method: :smtp
   mailer:
     smtp_settings:
       user_name: <%= ENV['AWS_SES_USERNAME'] %>
       password: <%= ENV['AWS_SES_PASSWORD'] %>
       address: email-smtp.us-east-1.amazonaws.com
       port: 587
       authentication: plain

 test:
   mailer_delivery_method: :test

 

And access this configuration using Rails.application.secrets

 Rails.application.secrets.mailer_default_from_email
 Rails.application.secrets.support_email
 Rails.application.secrets.mailer.smtp_settings # hash of smtp_settings configuration
 

Rails made use of SECRET_BASE_KEY for these encrypting the stored secrets.

The combination of config/secrets.yml, config/secrets.yml.enc and SECRET_BASE_KEY was confusing. It was not clear what one should be putting in these secrets, encrypted secrets and how SECRET_BASE_KEY is related to the setup in general.

To overcome this confusion secrets were replaced with credentials, and limited its usage to only encrypted credentials/ Using secrets is now deprecated.

Using config_for as a replacement for secrets.yml

Since secrets.yml is now deprecated we need a new way to store the configuration above. We can make use of existing functionality config_for to achieve the same desired effects.

First, we break down and move the configuration to a new config file. Since the configuration is about mailer, lets store the config config/mailer.yml

 # config/mailer.yml
 shared:
   default_from_email: "'Example' <[email protected]>"
   support_email: [email protected]
   delivery_method: :smtp
   smtp_settings:
     user_name: <%= ENV['AWS_SES_USERNAME'] %>
     password: <%= ENV['AWS_SES_PASSWORD'] %>
     address: email-smtp.us-east-1.amazonaws.com
     port: 587
     authentication: plain
 test:
   delivery_method: :test

 

We need to then load this configuration.

# config/application.rb
module MyApplication
  class Application < Rails::Application

    # Config settings
    config.mailer = config_for(:mailer)
  end
end

After loading this configuration we can start using the mailer configuration on Rails.configuration.mailer

 Rails.configuration.mailer.default_from_email
 Rails.configuration.mailer.support_email
 Rails.configuration.mailer.smtp_settings # hash of smtp_settings configuration
 

Using config_for helps us break down configuration into separate namespaced files, relative to what they useful for: mailer, host, exception_notifier and more.