Rockstor is a NAS distribution, kind of like FreeNAS, but rather than being based on BSD and ZFS, it’s based on Linux and btrfs.
I noticed they have a syncthing add on (a “rock-on”), so thought I should link it here: http://rockstor.com/docs/docker-based-rock-ons/syncthing.html
Syncthing is spreading!
Neat. I wish I could figure out how they handle updates, but that seems opaque. 
Good question. Looking at another thread http://forum.rockstor.com/t/updating-plex-in-rock-ons/316/3 it seems that rockstor do the updates to a docker image, and it looks like the build-in syncthing update mechanism should work. I will test it in a week or two.
@jpjp thanks for the link, I never heard of Rockstor before. I’m using FreeNAS and I’m quite happy with it - why do you prefer Rockstor?
Well with btrfs you can add disks as you need them, and increase the space as you do without losing redundancy (you just need to do a rebalance). With ZFS I can’t, unless I add two disks at a time and mirror each pair. But that’s too expensive for me 
Will see how stable it is over the next six months though!
I’m running rockstor with syncthing as well. Works nicely, updates seem to come through syncthings own mechanism. At least I always seem to have the newest version without doing anything.
A reason for rockstor was, that it wouldn’t need as much RAM as FreeNas. ZFS seems to be quite hungry…
@calmh I am the maintainer of Rockstor. We are working on the opacity, more documentation to come soon. But it would be great if there was an “official” Syncthing docker image. I’d be happy to work with you.
Other comments got it right, the image we currently use supports auto upgrade from within the app, which is great. You might want to look at it’s Dockerfile to see if there are any potential improvements possible.
Cool. I have a few starters on Docker images as well, as do others. Generally, I think the image needs only the binary, the CA certificates for HTTPS connections, and a resolv.conf. The rest is either unnecessary or goes on a volume, so size wise a Docker image doesn’t get much bigger than just the binary, which is neat.