Docker
Lately i’ve been wanting to expand my knowledge around containers. They are commonly used in most applicatons I run on VM’s. This creates alot of overhead as having an entire kernel , hardware drivers, and desktop environment is a little overkill in comparison to a container that can run the intended applicaton. An example of this jellyfin. Because of this , I would like to take this oppertunity to expand my skillset. I have been slowly working through my RHCSA exam prep which uses podman instead. However, the two technologies are very similar.
First steps into a containerized world
So what are containers? Containers provide an isolated environment for applications on a host. In short , containers provide an isolated CGROUP and filesystem for indiviual applicatons. Instead of having an entire kernel , you use a smaller slice of the processing pie so to speak. Each container is isolated from the host and other containers ( without extra configuration , more on that later).
Getting Started
Once you install docker, run ip addr. You will see a docker0 interface listed. This interface is the default bridge. In docker , you can use the docker bridge to network multiple containers.
If you run sudo docker network ls you can see all the active netowrk connections from docker containers. For clarification the term “driver” just means network type. When containers are added , by default they use the docker bridge as a switch ( kinda ).
Misc notes
- Per the docker documentation , if you use firewalld or ufw to manage your firewall, exposed ports on docker containers bypass your firewall rules