# config/puma.rb
​
max_threads_count = ENV.fetch('RAILS_MAX_THREADS') { 5 }
min_threads_count = ENV.fetch('RAILS_MIN_THREADS') { max_threads_count }
​
environment ENV.fetch('RAILS_ENV') { 'development' }
pidfile ENV.fetch('PIDFILE') { 'tmp/pids/server.pid' }
port ENV.fetch('PORT') { 3000 }
threads min_threads_count, max_threads_count
​
plugin :tmp_restart

# Gemfile
​
gem 'puma', '~> 4.1'