Load balancing Docker Registry v2 with HAProxy on Tutum - docker

Question

Did the following on Tutum:
Registry
Started a registry:2.1.1 service
Published the port 5000 and configured the registry service with:
VIRTUAL_HOST=https://my-registry.my-host.net
TCP_PORTS=5000/ssl
SSL_CERT="..."
Now, pointed the my-registry.my-host.net DNS to the registry service endpoint and testing the registry with:
docker login my-registry.my-host.net:5000
Works just fine, including the SSL!
HAProxy
Started a tutum/haproxy:latest service, published the 443 port, added API access and linked to the registry service, everything else is default
Pointed my-registry.my-host.net DNS to the haproxy service endpoint and tested the registry login with:
docker login my-registry.my-host.net
This time, the request fails with:
503 Service Unavailable
No server is available to handle this request.
What am I missing?
Note: everything was done from Tutum's Dashboard web UI.
Additionally, here's the generated haproxy.cfg from the HAProxy service container, for those who have experience with HAProxy, but not necessarily with Tutum:
https://gist.github.com/lazabogdan/3bf52984faa092b1a50b (note: the registry service ID has been masked with XXXXXXXX and the real FQDN has been replaced with my-registry.my-host.net)

Answer 1

Solved it.
I had to do the following:
Update the environment variable for the registry service from TCP_PORTS=5000/ssl to TCP_PORTS=5000
On the haproxy service, expose port 5000 on the container AND publish it on the host to port 443.
Now, I can successfully do:
docker login my-registry.my-host.net