DNS issues when replacing /etc/resolv.conf symlink with static file

[af85]

I have been symlinking /etc/resolv.conf to a stub file generated using the resolvconf service (i believe this is default behavior). I just pushed a change to all the desktops under my control to remove this symlink, and manage /etc/resolv.conf as a static file. Immediately after, DNS resolution failed for about 1/3 of the desktops under my control. I was able to fix this by sending the "touch /etc/resolv.conf" command to all our desktops (via saltstack).

Further information:

OS: Ubuntu Focal 20.04
Kernel: 5.11.0-27-generic or 5.11.0-41-generic
Method of deploying changes: saltstack

Reproduce:

if [ -L /etc/resolv.conf ]
then
  unlink /etc/resolv.conf
fi
cat > /etc/resolv.conf <<EOF
nameserver xx.xx.xx.xx
nameserver yy.yy.yy.yy
domain example.com
search example.com
options ndots:2 timeout:1
EOF
ping google.com # fails
touch /etc/resolv.conf
ping google.com # succeeds

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

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