[Bug 1830945] [NEW] DNS settings from interfaces file are ignored

Wed May 29 16:57:57 UTC 2019

Public bug reported:

Since a recent reboot (00:00 CEST on tuesday to be precise), DNS
settings from the interfaces file are no longer present in resolvconf. A
file /run/resolvconf/interface/eth0.inet exists but is empty.

This is happening on a xenial system. I have since rebooted once more,
with the same result.

These are the contents of /etc/network/interfaces:
---- 
iface lo inet loopback

auto eth0
iface eth0 inet static
	address 192.168.200.52
	netmask 255.255.255.0
	gateway 192.168.200.5
	dns-nameserver 192.168.200.5
	dns-nameserver 8.8.8.8

# second address
iface eth0 inet static
      address 192.168.200.67
      netmask 255.255.255.0
----

I'm running dnsmasq as a local DNS server on this system, which expects
to get the "upstream" dns servers from resolvconf and thus can no longer
resolve external addresses.

Until this recent reboot, this configuration has worked without issue
for many months, I have the etckeeper log to prove it :-).

Here are some relevant excerpts from the logs:
---- 
systemd[1]: Starting Clean up any mess left by 0dns-up...
systemd[1]: Reached target Remote File Systems.
systemd[1]: Started Clean up any mess left by 0dns-up.
systemd[1]: Starting Nameserver information manager...
systemd[1]: Started Nameserver information manager.
systemd[1]: Reached target Sockets.
systemd[1]: Reached target Basic System.
systemd[1]: Starting dnsmasq - A lightweight DHCP and caching DNS server...
systemd[1]: Starting Restore /etc/resolv.conf if the system crashed before the ppp link was shut down...
systemd[1]: Starting Raise network interfaces...
systemd[1]: Started ifup for eth0.
systemd[1]: Started Restore /etc/resolv.conf if the system crashed before the ppp link was shut down.
ifup[624]: /sbin/ifup: waiting for lock on /run/network/ifstate.eth0
systemd[1]: Started Raise network interfaces.
systemd[1]: Reached target Network.
dnsmasq[583]: dnsmasq: syntax check OK.
systemd[1]: Reached target Network is Online.
ntpdate[840]: name server cannot be used: Temporary failure in name resolution (-3)
dnsmasq[975]: started, version 2.75 cachesize 150
dnsmasq[975]: compile time options: IPv6 GNU-getopt DBus i18n IDN DHCP DHCPv6 no-Lua TFTP conntrack ipset auth DNSSEC loop-detect inotify
dnsmasq[975]: DNS service limited to local subnets
dnsmasq-dhcp[975]: DHCP, IP range 192.168.200.100 -- 192.168.200.200, lease time 1h
dnsmasq[975]: using local addresses only for domain myname.local
dnsmasq[975]: no servers found in /var/run/dnsmasq/resolv.conf, will retry
dnsmasq[975]: read /etc/hosts - 14 addresses
ntpd[1060]: error resolving pool 0.ubuntu.pool.ntp.org: Temporary failure in name resolution (-3)
systemd[1]: Started dnsmasq - A lightweight DHCP and caching DNS server.
systemd[1]: Reached target Host and Network Name Lookups.
ntpd[1060]: error resolving pool 1.ubuntu.pool.ntp.org: Temporary failure in name resolution (-3)
----

** Affects: resolvconf (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1830945

Title:
  DNS settings from interfaces file are ignored

Status in resolvconf package in Ubuntu:
  New

Bug description:
  Since a recent reboot (00:00 CEST on tuesday to be precise), DNS
  settings from the interfaces file are no longer present in resolvconf.
  A file /run/resolvconf/interface/eth0.inet exists but is empty.

  This is happening on a xenial system. I have since rebooted once more,
  with the same result.

  These are the contents of /etc/network/interfaces:
  ---- 
  iface lo inet loopback

  auto eth0
  iface eth0 inet static
  	address 192.168.200.52
  	netmask 255.255.255.0
  	gateway 192.168.200.5
  	dns-nameserver 192.168.200.5
  	dns-nameserver 8.8.8.8

  # second address
  iface eth0 inet static
        address 192.168.200.67
        netmask 255.255.255.0
  ----

  I'm running dnsmasq as a local DNS server on this system, which
  expects to get the "upstream" dns servers from resolvconf and thus can
  no longer resolve external addresses.

  Until this recent reboot, this configuration has worked without issue
  for many months, I have the etckeeper log to prove it :-).

  Here are some relevant excerpts from the logs:
  ---- 
  systemd[1]: Starting Clean up any mess left by 0dns-up...
  systemd[1]: Reached target Remote File Systems.
  systemd[1]: Started Clean up any mess left by 0dns-up.
  systemd[1]: Starting Nameserver information manager...
  systemd[1]: Started Nameserver information manager.
  systemd[1]: Reached target Sockets.
  systemd[1]: Reached target Basic System.
  systemd[1]: Starting dnsmasq - A lightweight DHCP and caching DNS server...
  systemd[1]: Starting Restore /etc/resolv.conf if the system crashed before the ppp link was shut down...
  systemd[1]: Starting Raise network interfaces...
  systemd[1]: Started ifup for eth0.
  systemd[1]: Started Restore /etc/resolv.conf if the system crashed before the ppp link was shut down.
  ifup[624]: /sbin/ifup: waiting for lock on /run/network/ifstate.eth0
  systemd[1]: Started Raise network interfaces.
  systemd[1]: Reached target Network.
  dnsmasq[583]: dnsmasq: syntax check OK.
  systemd[1]: Reached target Network is Online.
  ntpdate[840]: name server cannot be used: Temporary failure in name resolution (-3)
  dnsmasq[975]: started, version 2.75 cachesize 150
  dnsmasq[975]: compile time options: IPv6 GNU-getopt DBus i18n IDN DHCP DHCPv6 no-Lua TFTP conntrack ipset auth DNSSEC loop-detect inotify
  dnsmasq[975]: DNS service limited to local subnets
  dnsmasq-dhcp[975]: DHCP, IP range 192.168.200.100 -- 192.168.200.200, lease time 1h
  dnsmasq[975]: using local addresses only for domain myname.local
  dnsmasq[975]: no servers found in /var/run/dnsmasq/resolv.conf, will retry
  dnsmasq[975]: read /etc/hosts - 14 addresses
  ntpd[1060]: error resolving pool 0.ubuntu.pool.ntp.org: Temporary failure in name resolution (-3)
  systemd[1]: Started dnsmasq - A lightweight DHCP and caching DNS server.
  systemd[1]: Reached target Host and Network Name Lookups.
  ntpd[1060]: error resolving pool 1.ubuntu.pool.ntp.org: Temporary failure in name resolution (-3)
  ----

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