Today I leverage a configuration for my various networks LAN, IoT, GUEST, and DMZ using custom files in /etc/dnsmasq.d/X.conf that don't conflict with the default files in v5. I use a local file to redirect internal domain resolution to a private bind9 server and then of course for all the DHCP functions. I am reading the blog for v6 and was wondering what sort of impact is expected in v6 with such a type of configuration?
Thanks!
It is generally hard to say. A few bits and pieces are changing but nothing really substantial. It is very possible that your custom would just continue to work as it does right now. You could backup your /etc/pihole somewhere and then try the upgrade. If you cannot make it work, you can easily stop everything, restore /etc/pihole from your backup and go back to master with all components.
One major difference is that content in /etc/dnsmasq.d will not be loaded anymore by default - on one hand to prevent incompatibilities during upgrade but actually because there are still applications installing custom dnsmasq configuration that conflicts with stuff that is already present (remember the famous lxc.conf...). You can switch on importing custom config files through the config by setting
misc.etc_dnsmasq_d = true
either in /etc/pihole/pihole.toml or by simply running
sudo pihole-FTL --config misc.etc_dnsmasq_d true