LMS has been on my list of things to check out for a while, though looking at a few other suggestions, mopidy is looking like a strong choice - if I can get it set up both look at Jellyfin (starting a slow migration already…) and accept streams over DLNA, then it should cover a good portion of what I’d want.
Up until now I’ve been using docker and mostly manually configuring by dumping docker compose files in /opt/whatever and calling it a day. Portainer is running, but I mainly use it for monitoring and occasionally admin tasks. Yesterday though, I spun up machine number 3 and I’m strongly considering setting up something better for provisioning/config. After it’s all set up right, it’s never been a big problem, but there are a couple of bits of initial with that are a bit of a pain (mostly hooking up wireguard, which I use as a tunnel for remote admin and off-site reverse proxying.
Salt is probably the strongest contender for me, though that’s just because I’ve got a bit of experience with it.
The protocol would seem unlikely to satisfy the concept of “necessary”. It’s entirely possible for the protocol to be impossible to implement whilst not complying with GDPR. Might require the development of something more sharded - data pulling in real time, etc.