Puma doesn't start the Rails app after run

[igordeveloper23]

I am working on Ruby on Rails app.
I used Puma with Kubernetes.
I tried to run application on production with puma.
I set the preload option for puma to make sure the ruby on rails application run immediately after the puma start.
But when I check the start log, after puma start, the ruby on rails application doesn't start.
only if it gets the first request of application, then the RoR application starts.
When I found in the document, if I set preload option with puma, it will try eager loading of application. so It will start the Ruby on Rails application immedialy after the puma start.
But it doesn't now for my project.
How can I make sure the puma run and app run immediately?
If there is any misunderstanding for me about puma configuration, Please Let me know.
Thanks in advance