How to change the default rails server in Rails 3?

Question

I'm new to Rails and I'm wondering if there is an option to change the default rails server, i.e., webrick, for another one such as 'puma' or 'thin'. I know it is possible to specify which server to run with 'rails server' command, however I would like to use this command without specify the name of the server so it can run the default rails server. Is there a way to change the default rails server into a configuration file or something like this? Thanks in advance for your help!

Answer 1

Based on James Hebden's answer:

Add Puma to gemfile

# Gemfile
gem 'puma'

Bundle install it

bundle

Make it default, paste this code into script/rails above require 'rails/commands':

require 'rack/handler'
Rack::Handler::WEBrick = Rack::Handler.get(:puma)

So script/rails (in Rails 3.2.12) will look like:

#!/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__)
require 'rack/handler'
Rack::Handler::WEBrick = Rack::Handler.get(:puma)
require 'rails/commands'

Run server

rails s
=> Booting Puma

Answer 2

Rack (the interface between rails and a web server) has handlers for the default WEBrick, and also for Thin. If you place the following in your Gemfile in the root of your rails project

gem 'thin'

rails server will automatically use Thin. This has been the case since 3.2rc2.

This unfortunately only applies to Thin, as Rack does not have built-in support for Unicorn, and others.

For servers that have Rack handlers (again, sadly Unicorn does not), you can do a bit of a hack to get rails server to use them. In your scripts/rails file in the root of your rails project, you can add the below just above `require 'rails/commands'

require 'rack/handler'
Rack::Handler::WEBrick = Rack::Handler::<name of handler class>

This essentially resets the handler for WEBrick to point to the handler for the server you would like to use.

To get an understanding of the supported Rack handlers, take a look at the comments in the source: https://github.com/rkh/rack/blob/master/lib/rack/handler.rb