Rails Event Store browser on Heroku not loading due to 404 Not Found errors

[jkwuc89]

My team followed these instructions to install and configure the browser. Inside config/routes.rb, we use the following to mount the browser route. This is done inside the admin namespace.

mount RailsEventStore::Browser => '/event_store'

When we run our Rails app locally, the event store browser works as expected when browsing to http://localhost:3000/admin/event_store. When we attempt to load the browser inside our app when deployed to Heroku, we get a blank page with these errors:

I went through the Heroku build log and did not see anything amiss. I'm hoping someone has run into this and knows how to fix it. Thanks in advance.

[mostlyobvious]

Hi Keith! Can you please tell what is your rails_event_store version and can you also paste bigger routes.rb snippet that shows how this namespace is done?

[jkwuc89]

We are currently using rails_event_store version 2.7.0. Here is a bigger routes.rb snippet that shows the namespace.

namespace :admin do
    constraints ->(request) { Auth::AdminService.new(session: request.session).admin? } do
      mount Sidekiq::Web => '/sidekiq'
      mount RailsEventStore::Browser => '/event_store'
    end
end

admin? above is a method we use to determine if a user is configured as an admin in our system.

[lukaszreszke]

Hi @jkwuc89,

We tried to reproduce your issue but we weren't able to. We used new rails app with RES 2.7.0 and following routes.rb

Rails.application.routes.draw do
  namespace :admin do
    constraints ->(request) { true } do
      mount RailsEventStore::Browser => '/event_store'
    end
  end
end

It would be much easier to investigate if provide minimal configuration app that reproduces this issue.

[robinaugh]

Hi @lukaszreszke I'm on @jkwuc89's team and I'm looking into this issue a bit more. It looks like the problem is that the event store is rendering its CSS and JS using our herokuapp.com URLs rather than the domain we're using on top of Heroku.

i.e.

<script type="text/javascript" src="https://our-site.herokuapp.com/admin/event_store/ruby_event_store_browser.js"></script>

Should be

<script type="text/javascript" src="https://our-site.com/admin/event_store/ruby_event_store_browser.js"></script>

It looks like providing a path argument to RubyEventStore::Browser::App.for() is deprecated. What's the recommended way to specify the right URL here when mounting the RES browser? Thanks!

[mostlyobvious]

The reason why path and host became deprecated is because they're irrelevant. These values can be extracted from the Rack::Request and this is enough to figure out host and mount point:

rails_event_store/ruby_event_store-browser/spec/urls_spec.rb

Lines 24 to 33 in c876ab2

	specify do
	mocked_request =
	Rack::Request.new(
	Rack::MockRequest.env_for("http://example.net", script_name: "/res")
	)
	with_request = Urls.initial.with_request(mocked_request)
	expect(with_request.app_url).to eq("http://example.net/res")
	expect(with_request.api_url).to eq("http://example.net/res/api")
	end

I've just checked on a Heroku-deployed application with a custom domain:

  namespace :admin do
    authenticated :user, lambda { |u| u.admin? } do
      mount RailsEventStore::Browser, at: "/res", as: "res"
    end
  end

$ dig +short app.redacted-domain.io IN CNAME
redacted-heroku-dns-string.herokudns.com.

The browser is on https://app.redacted-domain.io/admin/res and requests:

https://app.redacted-domain.io/admin/res/ruby_event_store_browser.css
https://app.redacted-domain.io/admin/res/ruby_event_store_browser.js
https://app.redacted-domain.io/admin/res/bootstrap.js

Do you perhaps have a more complex routing setup or additional Rack middleware that could change Rack::Request#base_url and Rack::Request#script_name right before such request is passed to the browser in the application stack?

[robinaugh]

Closing the loop here - turns out the reason the rails event store browser was not working for us was because we were using nginx to proxy requests from a SPA javascript app back to our rails app. As soon as we retired that setup (by getting rid of the SPA 🎉 ), the rails event store browser worked just fine!