How to configure port server in Rails 5.1 - ruby-on-rails

Question

I need to configure the server port in config/boot.rb file. Looking at lib/rails/commands/server/server_command.rb we have this:
125 def perform
126 set_application_directory!
127 Rails::Server.new(server_options).tap do |server|
128 # Require application after server sets environment to propagate
129 # the --environment option.
130 require APP_PATH
131 Dir.chdir(Rails.application.root)
132 server.start
133 end
134 end
135
136 no_commands do
137 def server_options
138 {
139 user_supplied_options: user_supplied_options,
140 server: #server,
141 log_stdout: #log_stdout,
142 Port: port,
143 Host: host,
144 DoNotReverseLookup: true,
145 config: options[:config],
146 environment: environment,
147 daemonize: options[:daemon],
148 pid: pid,
149 caching: options["dev-caching"],
150 restart_cmd: restart_command
151 }
152 end
153 end
How can I configure Port from config/boot.rb then?
Thanks in advance.

Answer 1

I also tried to monkey patch boot.rb to change port, but no luck. Upon browsing I learned that Rails 5 comes with puma, which is configured in config/puma.rb. You can change the default port number in that file, or override it by setting the PORT environment variable before starting rails.
config/puma.rb
# Specifies the `port` that Puma will listen on to receive requests;
# default is 3000.
port ENV.fetch("PORT") { 3000 }
I hope this helps.