Must run systemd-resolve --status before DNS resolving is operative

Bug #1710410 reported by WoJ on 2017-08-12
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
systemd (Ubuntu)
Status tracked in Artful
Zesty
High
Dimitri John Ledkov
Artful
High
Dimitri John Ledkov

Bug Description

[Impact]
systemd-resolved is not enabled by default, therefore relies on dbus activation to become active and operatable and update resolvconf with resolved stub resolver

[Fix]
Enable systemd-resolved in the src:systemd package by default, even when libnss-resolve is not installed

[Regression Potential]
Minimal, simply the service is now started earlier in the boot, as part of the multi-user.targer, rather than awaiting for dbus activation from command line tool or the nss-resolved module.

[Testcase]
Debootstrap minimal zesty, without libnss-resolve package installed, boot and check that 127.0.0.53 is present in /etc/resolv.conf and that systemd-resolved.service is running

Context: fresh install of zesty via

debootstrap --include=nano,dbus,iputils-ping,iproute2 zesty zesty1 http://fr.archive.ubuntu.com/ubuntu

ran via asystemd-nspawn with a static IP

1. Upon first connexion, a ping fails:

root@zesty1:~# ping google.com
ping: google.com: Temporary failure in name resolution

2. The content of /etc/resolv.conf:

root@zesty1:~# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.

3. When running systemd-resolve --status:

root@zesty1:~# systemd-resolve --status
Global
         DNS Servers: 8.8.8.8
                      8.8.4.4
                      2001:4860:4860::8888
                      2001:4860:4860::8844
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
(...)

4. After running this command the resolution is miraculously restored:

root@zesty1:~# ping google.com
PING google.com (172.217.22.142) 56(84) bytes of data.
64 bytes from 172.217.22.142 (172.217.22.142): icmp_seq=1 ttl=53 time=2.62 ms
64 bytes from 172.217.22.142 (172.217.22.142): icmp_seq=2 ttl=53 time=1.93 ms

Changed in systemd (Ubuntu Artful):
status: New → Fix Committed
Changed in systemd (Ubuntu Zesty):
status: New → Triaged
importance: Undecided → High
Changed in systemd (Ubuntu Artful):
importance: Undecided → High
assignee: nobody → Dimitri John Ledkov (xnox)
Changed in systemd (Ubuntu Zesty):
assignee: nobody → Dimitri John Ledkov (xnox)
milestone: none → zesty-updates
Dimitri John Ledkov (xnox) wrote :

systemd (234-2ubuntu1) artful; urgency=medium
...
* Enable systemd-resolved by default
...

Changed in systemd (Ubuntu Artful):
status: Fix Committed → Fix Released
Changed in systemd (Ubuntu Zesty):
status: Triaged → In Progress
description: updated

Hello WoJ, or anyone else affected,

Accepted systemd into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/systemd/232-21ubuntu6 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-zesty to verification-done-zesty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-zesty. In either case, details of your testing will help us make a better decision.

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

Changed in systemd (Ubuntu Zesty):
status: In Progress → Fix Committed
tags: added: verification-needed verification-needed-zesty
Dimitri John Ledkov (xnox) wrote :

Starting with zesty container that has 232-21ubuntu5 installed.
Removed libnss-resolve.
Reboot.
Notice that systemd-resolve is not enabled.
Upgrade to 232-21ubuntu6.
.... and systemd-resolved was not enabled by default

This is a fail, the version number in postinst is too low when comparing whether or not resolved should be enabled or not.

tags: added: verification-failed verification-failed-zesty
removed: verification-needed verification-needed-zesty
Brian Murray (brian-murray) wrote :

Hello WoJ, or anyone else affected,

Accepted systemd into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/systemd/232-21ubuntu7 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-zesty to verification-done-zesty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-zesty. In either case, details of your testing will help us make a better decision.

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

tags: added: verification-needed verification-needed-zesty
removed: verification-failed verification-failed-zesty
Dimitri John Ledkov (xnox) wrote :

Upgrading from 232-21ubuntu5 to 232-21ubuntu7 enables systemd-resolved.service by default now.

tags: added: verification-done verification-done-zesty
removed: verification-needed verification-needed-zesty
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