Redirect from WWW to a non-WWW version of site in Rails.details:http://maxivak.com/redirect-from-www-to-a-non-www-version-of-site-in-rails/

rails-www-redirect-routes

Foo::Application.routes.draw do
 
  constraints(host: /^www\./i) do
    match '(*any)' => redirect { |params, request|
      URI.parse(request.url).tap { |uri| uri.host.sub!(/^www\./i, '') }.to_s
    }
  end
 
# other routes
 
end

redirect-apache

# in apache virtual host configuration file

RewriteEngine On
RewriteCond %{HTTP_HOST} ^www.example.com
RewriteRule ^ http://example.com%{REQUEST_URI} [L,R=301]

redirect-nginx

# in nginx server configuration file

server {
    listen       80;
    server_name  www.example.com;
    return       301 http://example.com$request_uri;
}

server {
    listen       80;
    server_name  example.com;
    ...
}

This should work for all methods

constraints(host: /^www\./i) do
    match '(*any)', via: :all, to: redirect { |_, request|
      # parse the current request url & tap in and remove www.
      URI.parse(request.url).tap { |uri| uri.host.sub!(/^www\./i, '') }.to_s
    }
end