This can be considered chore/feature.
As of now, Rails middlewares are unusable outside of a Rails app. I've been trying to use Rack::URLMap to map subpaths to different apps:
# config.ru app = Rack::URLMap.new( "/" => Rails.application, "/api" => App::API )
run app
this works, but I lose all the middlewares of the rails app, one of them being the authentication layer, which is handled by devise.
so I went further and have been trying to do something like this:
class CustomBuilder < Rack::Builder def call(env) req = Rails.application.send(:build_request, env) super(req.env) endend
api = CustomBuilder.new do run App::APIend # ugly, but rack doesn't allow me anything else api.instance_variable_get(:@use, Rack.application.config.middleware)
app = Rack::URLMap.new( "/" => Rails.application, "/api" => api
This will break, because Rack::Builder#to_app requires the middleware to be reversable <https://github.com/rack/rack/blob/master/lib/rack/builder.rb#L147>\. From the same link, you can see that the middleware must respond to .
The first approach seems to be to implement ActionDispatch::MiddlewareStack#reverse (it is an Enumerable, not an Array), and to implement ActionDispatch::MiddlewareStack::Middleware#(could be a simple alias to ActionDispatch::MiddlewareStack::Middleware#build). The #reverseimplementation is however "dangerous", because it means that existing #use calls which do global mutation will be executed as many times as the number of apps mapped in my Rack::URLMap app. This is why this would break <https://github.com/plataformatec/devise/issues/4291>, but then again, the requirement is from rack, so maybe this could be deviced there.
Rails version:
5.0.0.1