rootless: no DNS for containers within created network + host not using resolved stub resolver

[dustymabe]

On Fedora CoreOS we're currently not using the DNS stub resolver in systemd-resolved. There was a change in the podman 3:3.2.2-1.fc34 -> 3:3.2.3-1.fc34 transition that broke DNS for containers within a created network for this case.

Reproducer (on FCOS):

# as non-root user
podman network create testnetwork
podman run --rm -it --network=testnetwork registry.fedoraproject.org/fedora:34 getent hosts google.com
echo $?

To get an FCOS machine to test you can use podman machine (see article)

There is a lot more context on this bug over in coreos/fedora-coreos-tracker#923

[Luap99]

Where is /etc/resolv.conf symlinked and what is the content of the file?

[drobakowski]

> ls -la /etc/resolv.conf
lrwxrwxrwx. 1 root root 39 Jul 29 12:38 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf
> cat /etc/resolv.conf
# This is /run/systemd/resolve/resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 10.0.0.2
search ec2.internal

Rootless container:

> podman run --rm -it --network=testnetwork registry.fedoraproject.org/fedora:34 bash
> ls -la /etc/resolv.conf
-rw-r--r--. 1 root root 39 Aug 12 23:50 /etc/resolv.conf
[root@7030a4fe145f /]# cat /etc/resolv.conf
search dns.podman
nameserver 10.88.3.1

[Luap99]

Thank you, I will work on this today.

[Luap99]

PR #11230