Better flow for puma.rb

Author: dhh

railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt

@@ -2,8 +2,6 @@
 # are invoked here are part of Puma's configuration DSL. For more information
 # about methods provided by the DSL, see https://puma.io/puma/Puma/DSL.html.
 
-rails_env = ENV.fetch("RAILS_ENV", "development")
-
 # Puma starts a configurable number of processes (workers) and each process
 # serves each request in a thread from an internal thread pool.
 #
@@ -25,7 +23,12 @@ rails_env = ENV.fetch("RAILS_ENV", "development")
 threads_count = ENV.fetch("RAILS_MAX_THREADS") { 3 }
 threads threads_count, threads_count
 
-if rails_env == "production"
+# Specifies the `environment` that Puma will run in.
+rails_env = ENV.fetch("RAILS_ENV", "development")
+environment rails_env
+
+case rails_env
+when "production"
   # If you are running more than 1 thread per process, the workers count
   # should be equal to the number of processors (CPU cores) in production.
   #
@@ -36,21 +39,17 @@ if rails_env == "production"
   workers workers_count if workers_count > 1
 
   preload_app!
+when "development"
+  # Specifies a very generous `worker_timeout` so that the worker
+  # isn't killed by Puma when suspended by a debugger.
+  worker_timeout 3600
 end
 
 # Specifies the `port` that Puma will listen on to receive requests; default is 3000.
 port ENV.fetch("PORT") { 3000 }
 
-# Specifies the `environment` that Puma will run in.
-environment rails_env
-
 # Allow puma to be restarted by `bin/rails restart` command.
 plugin :tmp_restart
 
+# Only use a pidfile when requested
 pidfile ENV["PIDFILE"] if ENV["PIDFILE"]
-
-if rails_env == "development"
-  # Specifies a very generous `worker_timeout` so that the worker
-  # isn't killed by Puma when suspended by a debugger.
-  worker_timeout 3600
-end