How to change default port of a Rails 4 app?

Question

I know that I can start a rails server on another port via -p option. But I\'d like to setup another port per application as long as I start webrick.

An

Answer 1

For Rails 5.1:

# config/boot.rb

# ... existing code

require 'rails/command'
require 'rails/commands/server/server_command'

Rails::Command::ServerCommand.send(:remove_const, 'DEFAULT_PORT')
Rails::Command::ServerCommand.const_set('DEFAULT_PORT', 3333)