Rails custom project structure autoloading configs

I have a standard app that contains of sub-apps that we will slowly migrate into separate gems. The main problem is that each sub-app basically has an almost identical schema and very similar business logic that sometimes is really pretty much the same.

Currently, as a first step, we created a subfolder in lib/client with a structure like a typical rails app.

As an example, a concern for a ClientA looks like this/

module Client
  module ClientA
    module Concerns
      module MyConcern
       ...
    end 
  end
end

This all works fine and gets autoloaded by Zeitwerk.

However, when I want to create an initializer in a Rails way, I don't want to wrap it inside modules and make a class around it and this is where I am getting lib/clients/ClientA/config/initializers/custom_initializer.rb to define constant Clients::ClientA::Config::Initializers::CustomInitializer, but didn't (Zeitwerk::NameError)

This folder gets autoloaded like this

   config.autoload_paths += %W(#{config.root}/lib)
   config.autoload_paths += %W(#{config.root}/lib/client/**/*)

Is there a way how to

Blacklist the folder from being autoloaded by Zeitwerk?
Load it using require or in any other way without wrapping it in modules?

Solution

You can ignore parts of the project in zeitwerk using Loader#ignore. You can access rails zeitwerk autoloader via Rails.autoloaders.main.

So you should be able to add something like this to your application.rb:

Rails.autoloaders.main.ignore(Rails.root.join('lib/clients/*/config/initializers/*.rb'))

You'll then have to require them manually, maybe in an initializer in the main app directory. You could create a config/initializers/clients.rb with something like:

Dir[Rails.root.join('lib/clients/*/config/initializers/*.rb')].each do |filename|
  require filename
end