~~I think you need to add `SSL_CERT_FILE` and `SSL_KEY_FILE` to `environment`.~~ Scratch that. After looking at [config.py](https://github.com/etesync/etesync-dav/blob/a90a1760fda7f38c8e432503adbc35c9335749b2/etesync_dav/config.py) I notice the default value is set to that.