Docker docs:
Docker routes container traffic in the nat table, which means that packets are diverted before it reaches the INPUT and OUTPUT chains that ufw uses. Packets are routed before the firewall rules can be applied, effectively ignoring your firewall configuration.
I exposed them because I used the container for local development too. I just kept reseeding every time it got hacked before I figured I should actually look into security.
For local access you can use
127.0.0.1:80:80
and it won’t put a hole in your firewall.Or if your database is access by another docker container, just put them on the same docker network and access via container name, and you don’t need any port mapping at all.