Custom DNS an hosts entries for containers even when using --pod or --network=none

[flo-at]

Right now, when a container is started with either --pod or --network=none, it's not possible to use --dns or --add-host.
The docs for --add-host don't say anything about this limitation.
The docs for --dns correctly say that

This option cannot be combined with --network that is set to none

It might sound obvious: when network is "none", why would you want a DNS server or host entry?
Maybe my setup is a bit esoteric, but I use --network=none because I want podman to only setup an empty network namespace. I use an external system that injects veth interfaces into containers to connect them to the rest of the system. That way they can get their own public IP addresses, nftable rules, and use privileged ports while being rootless (which is crazy!).
So in the end I still need /etc/hosts and /etc/resolv.conf but I can't use --dns or --add-host because of the limitations above.

The same is true for pods. For most use-cases it makes sense to share the configuration of DNS and hosts entries between all containers in a pod. But just because containers share the same network namespace doesn't necessarily mean they have to share the same network configuration (which they don't in my case).

Imho it would be more consistent if these options were allowed independently.
--dns/--add-host on a container always adds the entries to the respective files on that container.
--dns/--add-host on a pod always adds the entries to all containers in the pod.

This also simplifies the documentation because what these arguments do doesn't depend on others (except the obviously conflicting ones; --no-hosts and --dns=none).
It also allows to seperate between shared configuration (on the pod) and individual configuration (on the container).
Changing that wouldn't even be a breaking change, I think.

I'm looking forward to hearing your opinions on this!