Integrate Sidekiq.logger into Rails.logger, closes #5021

Any use of Rails.logger in jobs will now go to the Sidekiq logger.

Changes.md

@@ -5,6 +5,9 @@
 HEAD
 ---------
 
+- **FEATURE**: Sidekiq.logger has been enhanced so any `Rails.logger`
+  output in jobs now shows up in the Sidekiq console. Remove any logger
+  hacks in your initializer and see if it Just Works™ now. [#5021]
 - **FEATURE**: Add `Sidekiq::Job` alias for `Sidekiq::Worker`, to better
   reflect industry standard terminology. You can now do this:
 ```ruby

lib/sidekiq/rails.rb

@@ -37,6 +37,17 @@ module Sidekiq
       end
     end
 
+    initializer "sidekiq.rails_logger" do
+      Sidekiq.configure_server do |_|
+        # This is the integration code necessary so that if code uses `Rails.logger.info "Hello"`,
+        # it will appear in the Sidekiq console with all of the job context. See #5021 and
+        # https://github.com/rails/rails/blob/b5f2b550f69a99336482739000c58e4e04e033aa/railties/lib/rails/commands/server/server_command.rb#L82-L84
+        unless ::ActiveSupport::Logger.logger_outputs_to?(::Rails.logger, STDOUT)
+          ::Rails.logger.extend(::ActiveSupport::Logger.broadcast(::Sidekiq.logger))
+        end
+      end
+    end
+
     # This hook happens after all initializers are run, just before returning
     # from config/environment.rb back to sidekiq/cli.rb.
     #