rails: `request.url` does not take `relative_url_root` into account

The URL returned by request.url ignores the value of Rails.config.action_controller.relative_url_root.

The documentation of ActionDisplay::HTTP:URL#url says that it “Returns the complete URL used for this request”. This is not true for projects that are not mounted under /.

This means that projects that use request.url cannot work unmodified when mounted under other directories with RAILS_RELATIVE_URL_ROOT.

In app/view/foo/index.html.erb write

request.url = <%= request.url %>
relative_url = <%= controller.relative_url_root %>

Setup Apache

RewriteRule      ^/bar(.*)$  http://localhost:4000/$1  [P,L]
ProxyPassReverse  /bar       http://localhost:4000/

Launch the Rails application

RAILS_RELATIVE_URL_ROOT=/bar bundle exec bin/rails -p 4000

The page should display

request.url = http://localhost/bar/foo
relative_url = /bar

The page displays

request.url = http://localhost/foo
relative_url = /bar

Please note the missing /bar in request.url.

Rails version: 4.2.5

Ruby version: 2.2.3

About this issue

This is still an issue in Rails 6 as well. It would be very nice if this could get fixed.

+24

This is still an issue in Rails 5.1.6. Any plans to tackle it?

+16

@nicolrx it is not closed.

Is there a workaround that can help with patching this?

A change that could solve this problem (while being less intrusive than #24396) is to

Generate a default config.ru that takes relative_url_root into account (PR #24412):

-run Rails.application
+map Rails.application.config.relative_url_root || '/' do
+  run Rails.application
+end

Document that the RAILS_RELATIVE_URL_ROOT variable must be set to the same value of SCRIPT_NAME (and maybe complain if the two differ).