How to run rails puma server with config file using 'rails s puma'

Question

I am able to run a puma server in rails using either rails s puma or just puma.

According to this answer, running rails s puma makes the server aware of the rails environment. It shows server errors etc that running puma alone does not.

I want to set a config file like so:

config/puma.rb

workers Integer(ENV['PUMA_WORKERS'] || 3)
threads Integer(ENV['MIN_THREADS']  || 1), Integer(ENV['MAX_THREADS'] || 16)

rackup      DefaultRackup
port        ENV['PORT']     || 3000
environment ENV['RACK_ENV'] || 'development'

...

If I run puma -C config/puma.rb everything works. However if I run rails s puma I can't work out how to give options to puma. I have tried the following:

rails s puma                     # Puma server works but no config file is passed in.
rails s puma -C config/puma.rb   # Invalid option -C
rails s puma -c config/puma.rb   # Undefined method 'workers'. So rails is
                                 # trying to use the config instead of puma?

I have also tried putting the config file at config/puma/development.rb as per the puma docs.

Appreciate any help on this :)

Answer 1

It is not possible to use rails s puma to load your puma configuration file, as confirmed here https://github.com/puma/puma/issues/512, you might want to take a look at a similar question here How do I get 'puma' to start, automatically, when I run `rails server` (like Thin does) where this is discussed