The primary folders you need concern yourself with are under “conf”. Items, Rules, Persistence, etc. If you have edited any of the files under userdata, be sure to grab those as well. The only file I can image you grabbing from there though is the logging configuration. This posting has all the pertinent info.
Once you create the new install, you may have to go through the initialization steps for some of the bindings. My.openhab and Nest bindings are two that I know for sure. There may be more.
I’m not sure what you mean by recover from an online source. I personally use a personal git server to backup and configuration control my configs, though that is a somewhat advanced approach.
The above link was written back when I was using OH 1.8 but the concepts are the same.
That is a long term solution. Short term you really just need to get the files off of your current install and on to the new install. Probably the easiest will be to copy the folders to the /boot folder, stick the SD card into another machine and copy them off. Once you install openHABian it will come with Samba installed I think. You should be able to access the Pi’s file system over the network and just copy the files over that way.
I know other people have use DropBox:
And some people check their configs into github itself, though I avoid that because I have usernames and passwords in my configs and it was easier to set up my own git server than it would be to mess with encrypting the necessary configs.
