Rack::LiveReload

Hey, you've got LiveReload in my Rack! No need for browser extensions anymore! Just plug it in your middleware stack and go!

Use this with guard-livereload for maximum fun!

Installation

Rails

Add the gem to your Gemfile.

group :development do
  gem 'leifcr-rack-livereload', require: 'rack-livereload'
end

Then add the middleware to your Rails middleware stack by editing your config/environments/development.rb.

# config/environments/development.rb

MyApp::Application.configure do
  # Add Rack::LiveReload to the bottom of the middleware stack with the default options:
  config.middleware.insert_after ActionDispatch::Static, Rack::LiveReload

  # or, if you're using better_errors:
  config.middleware.insert_before Rack::Lock, Rack::LiveReload

  # ...
end

Tweaking the options

# Specifying Rack::LiveReload options.
config.middleware.use(Rack::LiveReload,
  min_delay        : 500,    # default 1000
  max_delay        : 10_000, # default 60_000
  live_reload_port : 56789,  # default 35729
  host             : 'myhost.cool.wow',
  ignore           : [ %r{dont/modify\.html$} ]
)

In addition, Rack::LiveReload's position within middleware stack can be specified by inserting it relative to an exsiting middleware via insert_before or insert_after. See the Rails on Rack: Adding a Middleware section for more detail.

Sinatra / config.ru

require 'rack-livereload'

use Rack::LiveReload
# ...or...
use Rack::LiveReload, min_delay: 500, ...

How it works

The necessary script tag to bring in a copy of livereload.js is injected right after the opening head tag in any text/html pages that come through. The script tag is built in such a way that the HTTP_HOST is used as the LiveReload host, so you can connect from external machines (say, to mycomputer:3000 instead of localhost:3000) and as long as the LiveReload port is accessible from the external machine, you'll connect and be LiveReloading away!

Which LiveReload script does it use?

If you've got a LiveReload watcher running on the same machine as the app that responds to http://localhost:35729/livereload.js, that gets used, with the hostname being changed when injected into the HTML page.
If you don't, the copy vendored with rack-livereload is used.
You can force the use of either one (and save on the cost of checking to see if that file is available) with the middleware option :source => :vendored or :source => :livereload.