Public bug reported:
After upgrading to 19.10 I noticed that resolving hostnames stopped
working.
Quick release, which package and version info:
root@caret:~# lsb_release -r
Release: 19.10
root@caret:~# dpkg -S /etc/dhcp/dhclient-enter-hooks.d/resolved
systemd: /etc/dhcp/dhclient-enter-hooks.d/resolved
root@caret:~# apt-cache policy systemd
systemd:
Installed: 242-7ubuntu3
Candidate: 242-7ubuntu3
Version table:
*** 242-7ubuntu3 500
500 http://au.archive.ubuntu.com/ubuntu eoan/main amd64 Packages
100 /var/lib/dpkg/status
The file /etc/resolv.conf was pointing to the local instance of
systemd-resolved however there was no search line, indicating something wasn't
quite right.
Restarting the systemd-resolved service did recreate /etc/resolv.conf
with expected search line.
After much debugging, I've worked out what was going wrong.
The dhcp hook file /etc/dhcp/dhclient-enter-hooks.d/resolved has a bug
in the resolver state change logic.
This may also impact on tickets 1805183, 1832050, 1832053 and maybe
others.
When doing the md5sum of the old and new state, the command is wrong. It
isn't sending STDOUT (and optionally STDERR) to the temp file but rather
putting the md5sum command into the background and then creating an
empty file for both states. Which obviously isn't different, so systemd-
resolved doesn't restart.
Quick diff of a working version (I'm not capturing STDERR but one can
with "2>&1")
======= BEGIN PATCH =======
*** .brk-resolved-20191027 2019-10-27 11:19:56.210069032 +1030
--- resolved 2019-10-27 11:30:17.156381734 +1030
***************
*** 30,36 ****
mkdir -p $statedir
oldstate="$(mktemp)"
! md5sum $statedir/isc-dhcp-v4-$interface.conf
$statedir/isc-dhcp-v6-$interface.conf &> $oldstate
if [ -n "$new_domain_name_servers" ] ; then
cat <<EOF >$statedir/isc-dhcp-v4-$interface.conf
[Resolve]
--- 30,36 ----
mkdir -p $statedir
oldstate="$(mktemp)"
! md5sum $statedir/isc-dhcp-v4-$interface.conf
$statedir/isc-dhcp-v6-$interface.conf > $oldstate
if [ -n "$new_domain_name_servers" ] ; then
cat <<EOF >$statedir/isc-dhcp-v4-$interface.conf
[Resolve]
***************
*** 55,61 ****
fi
newstate="$(mktemp)"
! md5sum $statedir/isc-dhcp-v4-$interface.conf
$statedir/isc-dhcp-v6-$interface.conf &> $newstate
if ! cmp $oldstate $newstate; then
systemctl try-reload-or-restart systemd-resolved.service
fi
--- 55,61 ----
fi
newstate="$(mktemp)"
! md5sum $statedir/isc-dhcp-v4-$interface.conf
$statedir/isc-dhcp-v6-$interface.conf > $newstate
if ! cmp $oldstate $newstate; then
systemctl try-reload-or-restart systemd-resolved.service
fi
======= END PATCH =======
Also, the script removes the script removes the $oldstate file but
doesn't remove the $newstate file.
Not sure how this made it through QA testing... But breaking DHCP client
shouldn't happen like this.
ivan.
ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: network-manager 1.20.4-2ubuntu2
ProcVersionSignature: Ubuntu 5.3.0-19.20-generic 5.3.1
Uname: Linux 5.3.0-19-generic x86_64
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
Date: Sun Oct 27 11:48:33 2019
InstallationDate: Installed on 2017-04-21 (918 days ago)
InstallationMedia: Ubuntu-Server 17.04 "Zesty Zapus" - Release amd64 (20170412)
IpRoute:
default via 172.16.1.14 dev enp0s5
150.101.89.32/28 dev enp0s5 scope link
169.254.0.0/16 dev enp0s5 scope link metric 1000
172.16.1.0/24 dev enp0s5 proto kernel scope link src 172.16.1.120
IwConfig:
lo no wireless extensions.
enp0s5 no wireless extensions.
NetworkManager.state:
[main]
NetworkingEnabled=false
WirelessEnabled=true
WWANEnabled=true
ProcEnviron:
LANGUAGE=en_AU:en
TERM=vt100
PATH=(custom, no user)
LANG=en_AU.UTF-8
SHELL=/bin/bash
RfKill:
SourcePackage: network-manager
UpgradeStatus: Upgraded to eoan on 2019-10-26 (0 days ago)
nmcli-con:
nmcli-dev:
DEVICE TYPE STATE IP4-CONNECTIVITY IP6-CONNECTIVITY DBUS-PATH
CONNECTION CON-UUID CON-PATH
enp0s5 ethernet unmanaged unknown unknown
/org/freedesktop/NetworkManager/Devices/2 -- -- --
lo loopback unmanaged unknown unknown
/org/freedesktop/NetworkManager/Devices/1 -- -- --
nmcli-nm:
RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI
WWAN-HW WWAN
running 1.20.4 connected started unknown disabled enabled
enabled enabled enabled
** Affects: systemd (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug eoan
** Package changed: network-manager (Ubuntu) => systemd (Ubuntu)
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https://bugs.launchpad.net/bugs/1850009
Title:
Issue with detecting new state in dhclient-enter-hooks.d/resolved
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