We already have such support )nethserver-firewall-base/root/etc/e-smith/templates/etc/shorewall/shorewall.conf/60options at bcb8148c60d5df4685c02c65d4033f34f21e8101 · NethServer/nethserver-firewall-base · GitHub), but it’s not even documented because it doesn’t play well.
If you want to try it:
config setprop firewall Docker enabled
But you will surely face many issues.
Still, I think Docker is a must have somewhere in the near future.