How can I use Rails routes to redirect from one domain to another?

Question

My app used to run on foo.tld but now it runs on bar.tld. Requests will still come in for foo.tld, I want to redirect them to bar.tld.

How can I do this in rails rou

Answer 1

This does the job of the other answer. Though in addition, it preserves query strings as well. (Rails 4):

# http://foo.tld?x=y redirects to http://bar.tld?x=y
constraints(:host => /foo.tld/) do
  match '/(*path)' => redirect { |params, req|
    query_params = req.params.except(:path)
    "http://bar.tld/#{params[:path]}#{query_params.keys.any? ? "?" + query_params.to_query : ""}"
  }, via: [:get, :post]
end

Note: If you're dealing with full domains instead of just subdomains, use :domain instead of :host.