==== When DNS is not working ====
vagrant@ubuntu-jammy:~$ ping google.com
ping: google.com: Temporary failure in name resolution
vagrant@ubuntu-jammy:~$ resolvectl status
Global
Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub
Link 2 (enp0s3)
Current Scopes: none
Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
==== When DNS is working ====
vagrant@ubuntu-jammy:~$ ping google.com
PING google.com (172.217.160.110) 56(84) bytes of data.
64 bytes from tsa03s06-in-f14.1e100.net (172.217.160.110): icmp_seq=1 ttl=63
time=6.92 ms
64 bytes from tsa03s06-in-f14.1e100.net (172.217.160.110): icmp_seq=2 ttl=63
time=7.14 ms
^C
--- google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 6.915/7.029/7.144/0.114 ms
vagrant@ubuntu-jammy:~$ resolvectl status
Global
Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub
Link 2 (enp0s3)
Current Scopes: DNS
Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 10.0.2.3
DNS Servers: 10.0.2.3
DNS Domain: buildd
--
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/2028023
Title:
[jammy] DNS issue triggered by command "udevadm trigger --subsystem-
nomatch=input"
Status in OEM Priority Project:
New
Status in systemd package in Ubuntu:
New
Bug description:
[Summary]
In jammy server image, when we use NetworkManager as netplan renderer, we may
have DNS issue after executing command "udevadm trigger
--subsystem-nomatch=input" as super user, the udevadm command may also be
executed when we use "apt install XXXXXX" or "snap install XXXXXX".
[Steps to reproduce]
1. Login to a jammy server(jammy desktop environment works fine) image
environment with Vagrant
2. execute command "apt install network-manager"
3. modify netplan config to use NetworkManager as renderer
"""
# Let NetworkManager manage all devices on this system
network:
version: 2
renderer: NetworkManager
"""
4. reboot
5. execute command "ping google.com" first to make sure DNS works fine
6. execute command "udevadm trigger --subsystem-nomatch=input" as super user
7. execute command "ping google.com" to check if DNS still works fine
8. if DNS works fine, then repeat step 6-7, the fail rate is around 20-30%
[Other info]
I have tested the above mentioned steps for the following scenarios, which
work fine without DNS issue
1. Using focal server environment with Vagrant, there is no DNS issue
2. Using jammy server environment with Vagrant which has DNS issue, then add
the kinetic/kinetic-updates source list, install systemd(version:
251.4-1ubuntu7.3) from kinetic, and there is no DNS issue
If using focal server environment with Vagrant, then add the
jammy/jammy-updates source list, install systemd(version:
249.11-0ubuntu3.9) from jammy, then I will have DNS issue as well by
following the steps mentioned in [Steps to reproduce]
[Other info - Vagrantfile]
The following content is for the Vagrantfile that I used to test
"""
Vagrant.configure("2") do |config|
if Vagrant.has_plugin?("vagrant-timezone")
config.timezone.value = :host
end
config.vm.define "test" do |test|
test.vm.box = "ubuntu/jammy64"
test.vm.provider "virtualbox" do |vb|
vb.name = "test2"
vb.memory = "4096"
vb.cpus = 4
config.disksize.size = "50GB"
end
end
end
"""
[Fail rate]
20-30%
[Test script]
The following is the script that I used to test. Ideally it should run forever
"""
#!/bin/bash
set -ex
counter=1
while true; do
echo "$(date): test round ${counter}"
counter=$((counter + 1))
sudo udevadm trigger --subsystem-nomatch=input
ping google.com -c 2
sleep 0.5
done
"""
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