docker listens on port X. Accessible on machine. Also accessible from outside regardless of ufw.
No amount of time and experience will make you think that configuring a software to listen on a port will automagically poke a hole in the firewall.
It starts with the simple truth: `docker` doesn't `listen` on any port.
Or maybe a simple question: How can I run `docker run -p 8080 nginx` over and over without port conflict?
Or - lets expand scope even more. How is docker supposed to know about your choice of firewall? What about upstream firewalls? What about multiple versions of firewalls on a host (ufw vs. fern vs.)?
Can go on and on..
> It starts with the simple truth: `docker` doesn't `listen` on any port.
If I run the command below, `docker-proxy` starts listening on an incrementing port.
> Or maybe a simple question: How can I run `docker run -p 8080 nginx` over and over without port conflict?
Because you're not specifying a port on the host; you're specifying a port on the container. I've never used the single port form of `-p`; I would've guessed it was the same as `-p 8080:8080`.
May be a simple question: How are you able run nginx and open http:// localhost without it making any changes to the firewall. Can go on and on.