Rails reload! resets class variables, need to rerun some initializers

Question

Suppose I need to parse some configuration to instanciate some Service Singletons (that could be used with or without Rails).

A sample code example:

#services/my_service.rb
module MyService
    @config = nil

    def self.load_config(config)
      @config = config
    end

When using with Rail (or Capistrano, SInatra, etc.) I would use an initializer to boot up the service

#initializers/svc.rb
MyService.load_config(Rails.application.secrets.my_service.credentials)

But when used specifically with Rails, on every rails console restart!, this @config variable is cleared which is a problem...

Are there

• after-reload! hooks that I could use to re-run the initializer ?
• other types of variables that would be preserved during a restart! that I could use here ?

Answer 1

Seeing that people are still reading this, here is implementation I ended up with

# config/initializers/0_service_activation.rb
# Activation done at the end of file

module ServiceActivation
  def self.with_reload
    ActiveSupport::Reloader.to_prepare do
      yield
    end
  end

  module Slack
    def self.service
      ::SlackConnector
    end

    def self.should_be_activated?
      Utility.production? ||
      Utility.staging? ||
      (
        Utility.development? &&
        ENV['ENABLE_SLACK'] == 'true'
      )
    end

    def self.activate
      slack = service
      slack.webhook = Rails.application.secrets.slack&.dig(:slack_webhooks)
      Rails.application.secrets&.dig(:slack, :intercept_channel).try do |channel|
        slack.intercept_channel = channel if channel.present?
      end
      slack.activate
      slack
    end
  end

[
  ServiceActivation::Intercom,
  ServiceActivation::Slack,
  ServiceActivation::Google
] .each do |activator|
  ServiceActivation.with_reload do
    activator.activate if activator.should_be_activated?
    activator.service.status_report
  end
end

I am not showing my connector class SlackConnector, but basically you can probably guess the interface from the way it is called. You need to set the webhook url, and do other stuff. The implementation is decoupled, so it's possible to use the same SlackConnector in Rails and in Capistrano for deployment, so it's basically in the lib/ folder