Syncing folders across machines in Linux

Question

My question is similar to followings, but I don't find they match exactly what I am looking for. So I am here trying to get some experience of yours.

How to synchronize the home folder between multiple computers?

Sync $HOME across linux machines

I want to achieve following:

1. syncing certain folders among multiple machines, say 3 but might get increased,
2. customizable target folders, much better with negation and other complex rules,
3. since I might want to sync between laptops, it would be nice if it can be integrated into OS to sync automatically when connected to network,
4. a central server is preferred. It would be nice to have scheduled backup archives as well,
5. other customizable easy settings, like how to handle symlink etc,
6. conflict resolution can be arbitrary, but needs to be automatic,
7. It would be nice if things work in a subscriber-publisher pattern,
8. things need to work 100% automatically.

I am thinking of rsync at the beginning but after checking different answers, I noticed other options. But it's too much to try out all of them. Any existing tool already that can do the job? One thing to note that I do not what any external services(amazon, dropbox, etc), but something local that I can admin.

Answer 1

I used to use Unison in a previous job. It was used to keep synced a directory of documents between all employees (we were 3 or 4 at a time)

I never used it myself, but I saw multiple times the name Lsyncd which looks like a rsync daemon which pushes real time the modifications.