all the containers change IP addresses frequently. For home assistant a static IP address of the proxy manager is mandatory in order to reach it. For jellyfin it is useful to see which device accesses jellyfin. If the IP always changes, it doesn’t work properly.
How do I fix a container IP with podman compose (or docker)
The containers all have IPs unless you use the “host” network type, in which case it just stays in the host namespace, or “none” which ends up with an empty network namespace. And the IPs can indeed change. This is also why multiple containers can bind to the same port without colliding with eachother.
Docker kind of hides it from you because when you use
-pto publish a port, it sets up a proxy process for you to pass traffic from the port on the host to the port on the container.You usually have a
docker0bridge with an IP like 172.16.0.1, and if you runip ain a container it’ll have a single interface with an IP of 172.16.0.2.https://docs.docker.com/network/
Those are just the basic ones too, when macvlan, macvtap, ipvlan gets involved it gets even crazier. You can directly attach containers to the network such that your router assigns it an IP via DHCP like it’s just another device plugged on your network.
You can also share a network namespace with multiple containers, usually kubernetes/podman pods to enable for sidecar containers like Filebeat, Consul, Envoy, etcd and so on.
If you use rootless containers, it’ll use slirp4netns to emulate the network entirely in userspace.
In the cloud you usually end up with your pods directly attached to your VPC as well, like AWS Fargate serverless offerings.