`podman image scp` should support local Unix sockets

[vlk-charles]

Feature request description

podman image scp accepts connections added with podman system connection add. It should not "choke" on some of these connections. A connection can be specified as a local Unix socket file (according to the manual page):

podman system connection add otheruser unix:///run/user/1001/podman/podman.sock

However, the following command "chokes" on it:

$ podman image scp otheruser::someimage
Error: failed to connect: dial tcp: lookup unix:: no such host

Suggest potential solution

As Unix sockets over SSH seem to be supported (according to one of the examples in the manual page), I would expect local ones to be supported as well.

Have you considered any alternatives?

I also tried the option mentioned in the manual page as:

Images can also be transferred from rootful to rootless storage on the same machine without using sshd.

But that complained about missing machinectl. I know that can probably be made to work but I tired avoiding machinectl.

I guess it is possible to get SSH to work for localhost but that seems superfluous.

Additional context

Client:       Podman Engine
Version:      4.9.4-rhel
API Version:  4.9.4-rhel
Go Version:   go1.21.11 (Red Hat 1.21.11-1.el9_4)
Built:        Mon Jul  8 16:30:30 2024
OS/Arch:      linux/amd64