Proxy requests to GitLab by default
We could have a fallback action in the router of gitlab-workhorse where we just proxy to Unicorn. This is based on a suggestion from @ayufan .
Right now we have complicated routing in NGINX. This is OK for omnibus where we manage the NGINX configuration, but it causes trouble for people running GitLab from source or using Apache. It also means that changes in gitlab-workhorse often need parallel changes in NGINX.
If the default behaviour of gitlab-workhorse is to proxy everything it does not know to Unicorn, we can just tell NGINX to send all non-static-file requests to workhorse and be done with it. I think this increases the ease of deployment of GitLab and also the ease of GitLab development.
We could start by just creating the fallback in workhorse and experimenting with it on gitlab.com (by routing only a part of production traffic through it).