fail2ban : read whitelist from a database
Solution 1:
Sure, there is a way.
Fail2ban has an ignorecommand parameter, that you could use to check against SQL database.
Here is an example using sqlite.
Note: there is parameter ignorecache, which makes it fast and minimizes load (overhead to check on every failure), but it is relative "fresh" - it was released firstly in 0.10.4 and 0.11.1.