What is the replacement for ActionController::Base.relative_url_root? - ruby-on-rails

Question

I am porting a 2.x rails app to rails3; we'll call it foo-app. Foo-app is one section of a larger rails app and lives at main_rails_app.com/foo-app. Previously we just set up the following in our foo-app production config to ensure that our foo-app routes worked properly:
ActionController::Base.relative_url_root = "/foo-app"
However, with rails3, I now get:
DEPRECATION WARNING: ActionController::Base.relative_url_root is ineffective. Please stop using it.
I have since changed the config entry to the following:
config.action_controller.relative_url_root = "/foo-app"
This mostly works in that all calls to external resources (javascript/css/images) will use /foo-app. However, none of my routes change appropriately, or put another way, foo-app root_path gives me '/' when I would expect '/foo-app'.
Two questions:
What is the replacement for ActionController::Base.relative_url_root
if it is config.action_controller.relative_url_root, then why are my routes not reflecting the relative_url_root value I set?

Answer 1

You should be able to handle all that within the routes.rb file. Wrap all your current routes in scope; for instance.
scope "/context_root" do
resources :controller
resources :another_controller
match 'welcome/', :to => "welcome#index"
root :to => "welcome#index"
end
You can then verify your routing via the rake routes they should show your routes accordingly, including your context root(relative_url_root)

Answer 2

If you deploy via Passenger, use the RackBaseURI directive: http://www.modrails.com/documentation/Users%20guide%20Apache.html#RackBaseURI
Otherwise, you can wrap the run statement in your config.ru with the following block:
map ActionController::Base.config.relative_url_root || "/" do
run FooApp::Application
end
Then you only have to set the environment variable RAILS_RELATIVE_URL_ROOT to "/foo-app". This will even apply to routes set in gems or plugins.
Warning: do not mix these two solutions.

Answer 3

I feel like I must be over-complicating this and/or missing something, but this issue has been frustrating me for a while now, and here are my notes.
Summary
There are two separate issues with two points each for dynamic and static routes:
how to get routing to correctly match an incoming URL
for routes
for static files
how to generate URLs that include the relative_root
via url helpers
for static assets
One way to solve all four points:
Configure Nginx to strip the relative_root portion
This solves route matching; just write routes expecting URLs at / like development
Also static files are served as in development
Set RAILS_RELATIVE_URL_ROOT environment variable
This solves generated static asset helpers
Use the ScriptName middleware below (modify it to use the value from the environment)
This solves generated url helpers, e.g. users_path
Wrapping the Rails application in Rack::URLMap in config.ru (Christoph's answer)
# config.ru
map '/relative_root' do
run Myapp::Application
end
requires incoming URL contain the relative_url_root (Nginx can be configured to remove or retain this; see below)
Rack appends the relative_url_root to the Rack env SCRIPT_NAME rack/urlmap.rb:62
Rails adds the current request's SCRIPT_NAME to url_for options metal/url_for.rb:41
Rails' url_for prepends the script name when generating paths routing/url_for.rb:133
So that covers URLs generated by the url helpers, e.g. given UserController, users_path will be prefixed by the relative url root.
Set SCRIPT_NAME in middleware
# config.ru
class ScriptName
def initialize(app, name)
#app = app
#name = name
end
def call(env)
env['SCRIPT_NAME'] += #name
#app.call(env)
end
end
use ScriptName, '/relative_root'
run Rails.application
Has same effect as above, but
Requires that incoming URL NOT contain the relative_url_root
Setting RAILS_RELATIVE_URL_ROOT
value is saved in app.config.relative_url_root configuration.rb:41
which in turn affects asset paths asset_url_helper.rb:137
but that's it as far as I see
notably does not affect url helpers
Setting config.action_controller.relative_url_root
?? May affect assets compilation?
Overrides RAILS_RELATIVE_URL_ROOT env var?
Explicitly defining all routes under /relative_root (rizzah's answer)
# config/routes.rb
Myapp::Application.routes.draw do
scope '/relative_root' do
...
end
end
Url helpers will generate correct urls
Incoming URL must contain the relative url root (sensitive to Nginx configuration, see below), else "no route matches" exceptions
URLs requesting static assets, e.g. /relative_root/images/logo.png will result in "no route matches" exceptions. This may not be an issue if nginx is serving static assets anyway.
Nginx config
Given a config like this:
upstream myapp {
server localhost:3000;
}
server {
...
location /relative_root {
proxy_pass http://myapp/;
}
}
Nginx will strip out the /relative_root, and the Rails app will not see it. If you need the Rails app so see it, one way is to change the proxy_pass line:
...
proxy_pass http://myapp/relative_root/;
...