ubuntu/* and debian/* have no network

[marehr]

I just tested ubuntu/focal, ubuntu/jammy, and debian/sid.

The images were installed like this:

nspawn -i ubuntu/focal/tar

machinectl start ubuntu-focal-tar

machinectl login ubuntu-focal-tar

➜  ~ sudo machinectl login ubuntu-focal-tar
Connected to machine ubuntu-focal-tar. Press ^] three times within 1s to exit session.

Ubuntu 20.04 LTS focal pts/1

focal login: root
Password: 
Welcome to Ubuntu 20.04 LTS (GNU/Linux 6.2.1-arch1-1 x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

root@focal:~# ping www.google.de
ping: www.google.de: Temporary failure in name resolution

root@focal:~# apt update
Err:1 http://archive.ubuntu.com/ubuntu focal InRelease
  Temporary failure resolving 'archive.ubuntu.com'
Err:2 http://security.ubuntu.com/ubuntu focal-security InRelease
  Temporary failure resolving 'security.ubuntu.com'
Err:3 http://archive.ubuntu.com/ubuntu focal-updates InRelease
  Temporary failure resolving 'archive.ubuntu.com'
Reading package lists... Done        
Building dependency tree       
Reading state information... Done
55 packages can be upgraded. Run 'apt list --upgradable' to see them.
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal/InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/InRelease  Temporary failure resolving 'security.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal-updates/InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.

fedora-34-tar on the other hand worked. Maybe you can help :)

[Edu4rdSHL]

It's an issue when using private networks, which I assume you are using as it's the default configuration. You can simply try setting up a MACVLAN or IPVLAN in your .nspawn file and it will work... honestly, it isn't clear why it doesn't work for specific distros, but I will continue investigating.

[neitsab]

Just wanted to update this mentioning that it's the same situation with the arch container image, using default machinectl start command. I had to create /etc/systemd/nspawn/archlinux-archlinux-tar with the following content (taken from the Arch Wiki):

[Network]
VirtualEthernet=no

and after restarting the container it worked.

Maybe this could be documented in nspawn/nspawn's README and/or the website's FAQ for those less familiar with machinectl inner working?