How to redirect without www using Rails 3 / Rack?

Question

I understand there are a lot of questions that answer this. I'm familiar with .htaccess and nginx.conf methods, but I do not have access to such traditional configuration methods on heroku.

Simone Carletti gave this answer that leverages Rails 2.x Metals, but I'm using Rails 3 and this isn't compatible. Redirect non-www requests to www urls in Rails

Please note:

I'm not looking for a simple before_filter in my ApplicationController. I'd like to accomplish a rewrite similar to Simone's. I believe this is job for the webserver or middleware like Rack at the very least, so I'd like to leave this bit out of the actual app code.

Goal

redirect                to                  status
----------------------------------------------------
www.foo.com             foo.com             301
www.foo.com/whatever    foo.com/whatever    301

Only hosts matching /^www\./ should be redirect. All other requests should be ignored.

Answer 1

For Rails 4 the above solutions have to be appended with the Verb construction e.g. via: [:get, :post]. Duke's solution becomes:

  constraints(:host => /^www\./) do
    match "(*x)" => redirect { |params, request|
      URI.parse(request.url).tap {|url| url.host.sub!('www.', '') }.to_s
    }, via: [:get, :post]
  end

Answer 2

I really like using the Rails Router for such things. Previous answers were good, but I wanted something general purpose I can use for any url that starts with "www".

I think this is a good solution:

constraints(:host => /^www\./) do
  match "(*x)" => redirect { |params, request|
    URI.parse(request.url).tap {|url| url.host.sub!('www.', '') }.to_s
  }
end

Answer 3

In Rails 3

#config/routes.rb
Example::Application.routes.draw do
  constraints(:host => "www.example.net") do
    match "(*x)" => redirect { |params, request|
      URI.parse(request.url).tap { |x| x.host = "example.net" }.to_s
    }
  end
  # .... 
  # .. more routes ..
  # ....
end