Well, what get’s printed to openhab.log should make it pretty apparent whether OH is completely restarting of the .rules files are just reloading. If restarting you will see a bunch of “stopping service X” type logs followed by “started service x” type logs when OH comes back up.
Do you see any “Loading module…” log statements when you link to an Item? Are all of your Rules in one .rules file or many .rules files? If many, do all of your system started Rules run or only some of them?
I created and linked an Item to a Channel through PaperUI that I did not previously have an Item linked to and again (new Item, new Link), I did not see anything unexpected. Neither my rules ran (I’m using Scripted Automation so can’t say if .rules files would have run) nor openHAB restarted. So I don’t think it’s specifically Docker at play here.
Removing the Link and the Item also did not cause anything unusual to happen. I’m running the latest SNAPSHOT, not RC1 (I got hit by the MQTT bug that was fixed yesterday).
You would see that behavior if OH decided it needed to reload your files for some reason.