[Bug 1805183] Re: systemd-resolved constantly restarts on Bionic upgraded from Xenial

Thu Nov 14 15:00:40 UTC 2019

Hello Neil, or anyone else affected,

Accepted systemd into bionic-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/systemd/237-3ubuntu10.32 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-bionic to verification-done-bionic. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-bionic. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: systemd (Ubuntu Bionic)
       Status: In Progress => Fix Committed

** Tags added: verification-needed-bionic

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https://bugs.launchpad.net/bugs/1805183

Title:
  systemd-resolved constantly restarts on Bionic upgraded from Xenial

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in systemd source package in Cosmic:
  Won't Fix
Status in systemd source package in Disco:
  Fix Committed
Status in systemd source package in Eoan:
  Fix Committed
Status in systemd source package in Focal:
  Fix Released

Bug description:
  [Impact]
  Log noise due to needless restart of resolved on lease expiry, maybe loss of cached state?
  Application that require Name Resolution may fail while the service is being unnecessarily restarted

  [Test case]
  (1) Append make_resolv_conf to the end of the file, so it gets executed
  (2) Execute the file with bash -x and different settings and ensure there are no restarts if the settings are the same, and that there are if settings change; for example:

  sudo new_domain_name_servers=8.8.4.4 interface="wlp61s0" reason=REBIND bash -x debian/extra/dhclient-enter-resolved-hook
  sudo new_domain_name_servers=8.8.4.4 interface="wlp61s0" reason=REBIND bash -x debian/extra/dhclient-enter-resolved-hook
  => no restart
  sudo new_domain_name_servers=8.8.8.8 interface="wlp61s0" reason=REBIND bash -x debian/extra/dhclient-enter-resolved-hook
  => should restart
  sudo new_domain_name_servers=8.8.8.8 interface="wlp61s0" reason=REBIND bash -x debian/extra/dhclient-enter-resolved-hook
  => no restart
  sudo new_domain_name_servers=8.8.4.4 interface="wlp61s0" reason=REBIND bash -x debian/extra/dhclient-enter-resolved-hook
  => should restart

  [Regression potential]
  The change only restarts resolved when the settings change. If there's a bug in the logic, resolved might not be restarted when it should be. Also, since there will be less restarts of resolved, it will run longer, so if there are memory leaks they will become more apparent.

  [other info]

  this fix was included in the initial release of systemd for eoan, but
  the fix required the additional change in bug 1849608.  Both the
  original patch plus that change (to avoid using bash-specific &>) are
  included in the b/d patch for this bug.

  [Original bug report]
  If a cloud server is upgraded from Xenial to Bionic, the dhclient system remains in place and any DHCP lease refreshes cause a needless restart of the system-resolved daemon

  Nov 26 16:59:41 srv-qvjhx dhclient[825]: DHCPREQUEST of 10.226.209.106 on ens3 to 10.226.209.105 port 67 (xid=0x2bd41d7d)
  Nov 26 16:59:41 srv-qvjhx dhclient[825]: DHCPACK of 10.226.209.106 from 10.226.209.105
  Nov 26 16:59:41 srv-qvjhx systemd[1]: Stopping Network Name Resolution...
  Nov 26 16:59:41 srv-qvjhx systemd[1]: Stopped Network Name Resolution.
  Nov 26 16:59:41 srv-qvjhx systemd[1]: Starting Network Name Resolution...
  Nov 26 16:59:41 srv-qvjhx systemd-resolved[1609]: Positive Trust Anchors:
  Nov 26 16:59:41 srv-qvjhx systemd-resolved[1609]: . IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5
  Nov 26 16:59:41 srv-qvjhx systemd-resolved[1609]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d
  Nov 26 16:59:41 srv-qvjhx systemd-resolved[1609]: Negative trust anchors: 10.in-addr.arpa 16.172.in-addr.arpa 17.172.in-addr.arpa 18.172.in-addr.arpa 1
  Nov 26 16:59:41 srv-qvjhx systemd-resolved[1609]: Using system hostname 'srv-qvjhx'.
  Nov 26 16:59:41 srv-qvjhx systemd[1]: Started Network Name Resolution.
  Nov 26 16:59:41 srv-qvjhx systemd[1]: Starting resolvconf-pull-resolved.service...
  Nov 26 16:59:41 srv-qvjhx dhclient[825]: bound to 10.226.209.106 -- renewal in 1466 seconds.
  Nov 26 16:59:41 srv-qvjhx systemd[1]: Started resolvconf-pull-resolved.service.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: ubuntu-release-upgrader-core 1:16.04.25
  ProcVersionSignature: Ubuntu 4.4.0-139.165-generic 4.4.160
  Uname: Linux 4.4.0-139-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.18
  Architecture: amd64
  CrashDB: ubuntu
  Date: Mon Nov 26 16:17:52 2018
  PackageArchitecture: all
  SourcePackage: ubuntu-release-upgrader
  UpgradeStatus: No upgrade log present (probably fresh install)

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