Implement TLS and more logging

[NiLuJe]

Also ship a systemd unit file in contrib for non-Docker deployment.

[NiLuJe]

Story time: I needed a KOSync server to test koreader/koreader#10839, and yours happened to be both the most recently updated, neat, and was something I could actually deploy quickly and without going mad in the process.

Because I apparently had some extra time to waste, I then went ahead and mangled it to add TLS, listen on a dual-stack socket by default, and add some more logging.

Fair warning: I've never touched Rust before, and it's a language that very strongly doesn't agree with me, so, here be dragons ;).

[szaffarano]

Story time: I needed a KOSync server to test koreader/koreader#10839, and yours happened to be both the most recently updated, neat, and was something I could actually deploy quickly and without going mad in the process.

Because I apparently had some extra time to waste, I then went ahead and mangled it to add TLS, listen on a dual-stack socket by default, and add some more logging.

Fair warning: I've never touched Rust before, and it's a language that very strongly doesn't agree with me, so, here be dragons ;).

Hi, I know it's been a while, but just in case you still need this feature, I've been working on a sync server that, since the latest release, supports native TLS termination. It also has available binaries and Docker images for ARM and AMD targets.

systemd service is still a WIP 😅

[NiLuJe]

Well, it's been in prod ever since and nobody's complained yet (and nothing imploded either :D), so, I'm happy with it on my end so far ;).