How to change Rails 3 server default port in develoment?

Question

First - do not edit anything in your gem path! It will influence all projects, and you will have a lot problems later...

In your project edit script/rails this way:

#!/usr/bin/env ruby
# This command will automatically be run when you run "rails" with Rails 3 gems installed from the root of your application.

APP_PATH = File.expand_path('../../config/application',  __FILE__)
require File.expand_path('../../config/boot',  __FILE__)

# THIS IS NEW:
require "rails/commands/server"
module Rails
  class Server
    def default_options
      super.merge({
        :Port        => 10524,
        :environment => (ENV['RAILS_ENV'] || "development").dup,
        :daemonize   => false,
        :debugger    => false,
        :pid         => File.expand_path("tmp/pids/server.pid"),
        :config      => File.expand_path("config.ru")
      })
    end
  end
end
# END OF CHANGE
require 'rails/commands'

The principle is simple - you are monkey-patching the server runner - so it will influence just one project.

UPDATE: Yes, I know that the there is simpler solution with bash script containing:

#!/bin/bash
rails server -p 10524

but this solution has a serious drawback - it is boring as hell.

I like to append the following to config/boot.rb:

require 'rails/commands/server'

module Rails
  class Server
    alias :default_options_alias :default_options
    def default_options
      default_options_alias.merge!(:Port => 3333)
    end    
  end
end

One more idea for you. Create a rake task that calls rails server with the -p.

task "start" => :environment do
  system 'rails server -p 3001'
end

then call rake start instead of rails server

Combining two previous answers, for Rails 4.0.4 (and up, presumably), this suffices at the end of config/boot.rb:

require 'rails/commands/server'

module Rails
  class Server
    def default_options
      super.merge({Port: 10524})
    end
  end
end

We're using Puma as a web server, and dotenv to set environment variables in development. This means I can set an environment variable for PORT, and reference it in the Puma config.

# .env
PORT=10524


# config/puma.rb
port ENV['PORT']

However, you'll have to start your app with foreman start instead of rails s, otherwise the puma config doesn't get read properly.

I like this approach because the configuration works the same way in development and production, you just change the value of the port if necessary.

Inspired by Radek and Spencer... On Rails 4(.0.2 - Ruby 2.1.0 ), I was able to append this to config/boot.rb:

# config/boot.rb

# ...existing code

require 'rails/commands/server'

module Rails
  # Override default development
  # Server port
  class Server
    def default_options
      super.merge(Port: 3100)
    end
  end
end

All other configuration in default_options are still set, and command-line switches still override defaults.