CodeRack

About

There are often times when you'll need to redirect requests for some domains or subdomains to a single canonical host. This middleware lets you specify the canonical host for your application, and will perform a 301 redirect for all non-canonical requests. One of the most common use cases is to redirect the a subdomain like www to the the root domain, or vice versa.

Usage

In its simplest case, just specify your canonical host.

use CanonicalHost, 'example.com'

You can also pass a block that will be evaluated, and its return value will be used as the canonical host. This is often useful when you're targeting multiple environments.

use CanonicalHost do
  case Rails.env.to_sym
    when :staging then 'staging.example.com'
    when :production then 'example.com'
  end
end

Code

class CanonicalHost
  def initialize(app, host=nil, &block)
    @app = app
    @host = (block_given? && block.call) || host
  end
 
  def call(env)
    if url = url(env)
      [301, { 'Location' => url }, ['Redirecting...']]
    else
      @app.call(env)
    end
  end
 
  def url(env)
    if @host && env['SERVER_NAME'] != @host
      url = Rack::Request.new(env).url
      url.sub(%r{\A(https?://)(.*?)(:\d+)?(/|$)}, "\\1#{@host}\\3/")
    end
  end
  private :url
end