Configure at proper scope

Place configuration options at their proper scope within the framework hierarchy. Avoid tight coupling between components and ensure user configurations aren’t accidentally overridden.

When working with configurations:

1. Avoid direct framework references in components

   Instead of accessing global constants directly:

   def perform(event)
     ex = event.payload[:exception_object]
     if ex
       cleaned_backtrace = Rails.backtrace_cleaner.clean(ex.backtrace)
       # ...
     end
   end
   

   Pass dependencies through proper configuration channels:

   # In the railtie
   initializer "active_job.backtrace_cleaner" do
     ActiveJob::LogSubscriber.backtrace_cleaner = Rails.backtrace_cleaner
   end
      
   # In the component
   def perform(event)
     ex = event.payload[:exception_object]
     if ex
       cleaned_backtrace = self.class.backtrace_cleaner.clean(ex.backtrace)
       # ...
     end
   end
   

2. Respect user configuration

   Check if user has already set a configuration before applying defaults:

   # Bad: Overwrites user configuration
   initializer "active_record.attributes_for_inspect" do |app|
     ActiveRecord::Base.attributes_for_inspect = :all if app.config.consider_all_requests_local
   end
      
   # Good: Respects user configuration
   initializer "active_record.attributes_for_inspect" do |app|
     if app.config.consider_all_requests_local && app.config.active_record.attributes_for_inspect.nil?
       ActiveRecord::Base.attributes_for_inspect = :all
     end
   end
   

3. Avoid mutating shared configuration objects

   Always duplicate default configuration objects before modification:

   # Bad: Mutates shared constant
   route_set_config = DEFAULT_CONFIG
   route_set_config[:some_setting] = value
      
   # Good: Works with a copy
   route_set_config = DEFAULT_CONFIG.dup
   route_set_config[:some_setting] = value
   

4. Use environment-specific configuration via config, not conditionals

   Instead of hardcoding environment checks:

   # Bad: Direct environment checking in middleware
   if (Rails.env.development? || Rails.env.test?) && logger(request)
     # ...
   end
   

   Make behavior configurable:

   # Good: Configurable behavior
   def initialize(app, warn_on_no_content_security_policy = false)
     @app = app
     @warn_on_no_content_security_policy = warn_on_no_content_security_policy
   end
      
   # Later in code
   if @warn_on_no_content_security_policy && logger(request)
     # ...
   end
   

Following these practices ensures components remain properly isolated and configurations behave predictably across different environments and application setups.