Sinatra (and probably other Rack apps) do not properly generate links

[halfbyte]

I'll create a simple test case, but for now, here's the info I gathered:

When nginx proxies the request to the rack app, the sub folder path information gets lost and if you use to/url to generate proper url's you'll always end up with urls that are constructed from the root.

Let's say I created an app "example", and it runs at foo.local/example. Every url constructed with url() or to() in sinatra ends up being wrongly constructed, for example url('/foo') returns /foo instead of /example/foo.

I have not completely understood the underlying problem, as sinatra claims to support reverse proxying and sub folders. One issue seems to be that SCRIPT_NAME is empty, maybe adding that to the proxy headers could help.

As sinatra is a good fit for quick hacks, I consider this a problem :)

I'll update this issue as I gather more information.

[halfbyte]

I have a workaround and a possible fix:

The workaround is to add "rack_injection" to the Gemfile and add this to the config.ru file of your sinatra app (replace $APP with the name of your app, of course):

require 'rack_injection'
use RackInjection, 'SCRIPT_NAME' => '$APP'

The fix for experimental platform would be to set SCRIPT_NAME as a header in the nginx config. I hope.

[halfbyte]

Okay, next problem with url(): if running via the protonet proxy (foobar.protonet.info) the X_FORWARDED_PROTO header is not correctly set (I assume it gets lost in the go request router?) which generates http links which makes the protonet proxy redirect to https.

And here I was wondering how somehow magically POST requests were turned into GET requests :)

[tiff]

Thanks @halfbyte we will look into this as soon as possible. The URL issue is something that's very high on our todo list :)
The X_FORWARDED_PROTO fix seems like a low hanging fruit that might be fixed even earlier. I'll keep you posted.

[tiff]

@halfbyte experimental-platform/platform-dokku#13 this should fix the X_FORWARDED_PROTO issue. Would this also be the place to put the SCRIPT_NAME or shouldn't this rather be an environment variable?

[tiff]

I would appreciate your feedback @halfbyte 😃

[halfbyte]

@tiff I think the nginx config would be the correct place to set the SCRIPT_NAME, yes. Basically, the SCRIPT_NAME must match the path you mount the sinatra app at, so, if the app name is jinglebells, the SCRIPT_NAME should be jinglebells as well, if the app is then to be found at mybox.protonet.info/jinglebells.

I'm not entirely sure it's the correct fix for my problem, but it will be worth a try.

[kdomanski]

@halfbyte can I get some sample code to reproduce the issue?