[Bug 1032855] Re: resolvconf modifies real file /etc/resolv.conf in lieu of /run/resolvconf/resolv.conf

[Steve Langasek]

This is nothing to do with resolvconf.  dhclient itself updates
/etc/resolv.conf when it receives DNS information from DHCP; and so does
Network Manager.  The point of having resolvconf as part of the base
system in Ubuntu is precisely that all the network management tools want
to be able to provide dynamic DNS information, and resolvconf is the
first standard framework to let users control this *without* having to
chase down half a dozen scripts.

Far from being a "minimum breakage path", replacing the /etc/resolv.conf
file with a symlink means you now don't benefit from the (recommended)
resolvconf framework.

A more effective way to manage this is by creating
/etc/resolvconf/resolv.conf.d/head with your preferred nameserver
information.  resolvconf knows that ::1 is special and won't include any
other dynamic nameserver information.

** Changed in: resolvconf (Ubuntu)
       Status: New => Invalid

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Title:
  resolvconf modifies real file /etc/resolv.conf in lieu of
  /run/resolvconf/resolv.conf

Status in “resolvconf” package in Ubuntu:
  Invalid

Bug description:
  I manually compiled and installed the unbound DNS resolver on my 12.04
  server (upgraded from a 10.04).

  Yesterday, after reading http://www.stgraber.org/2012/02/24/dns-in-
  ubuntu-12-04/ and
  http://manpages.ubuntu.com/manpages/precise/man8/resolvconf.8.html I
  took the "minimum breakage path" and simply erased the symlink
  /etc/resolv.conf (which points to /run/resolvconf/resolv.conf) and
  created a plain file for /etc/resolv.conf using ::1 as my only
  resolver.

  However, today I found that the file /etc/resolv.conf had been
  rewritten with the same contents it had before.

  Checking a little I found the file modification time was 12:35 and
  found the following on my syslog:

  Aug  3 12:35:40 abako dhclient: DHCPREQUEST of 66.228.40.90 on eth0 to 207.192.68.72 port 67
  Aug  3 12:35:40 abako dhclient: DHCPACK of 66.228.40.90 from 207.192.68.72
  Aug  3 12:35:40 abako dhclient: bound to 66.228.40.90 -- renewal in 38228 seconds.

  So, the primary cuplrit seems to be resolvconf.

  What's more, the file modification time for
  /run/resolvconf/resolv.conf is on June 20th (the day I upgraded from
  10.04 to 12.04.

  So, IMHO, either resolvconf has a bug or the following paragraph of
  its manpage is plain wrong:

        The  most  important  piece  of  software  that   subscribes   to   the
         notification  service  is  the  set of functions that make up the GNU C
         Library resolver(3).   When  nameserver  information  is  updated,  the
         script    /etc/resolvconf/update.d/libc    writes    a   new   resolver
         configuration file to /run/resolvconf/resolv.conf  and  then  runs  the
         scripts  in  /etc/resolvconf/update-libc.d/.   To make the resolver use
         the dynamically generated resolver configuration file the administrator
         should   ensure   that   /etc/resolv.conf   is   a   symbolic  link  to
         /run/resolvconf/resolv.conf.   This   link   is   never   modified   by
         resolvconf(8).  If you find that /etc/resolv.conf is not being updated,
         check to make sure that the link is intact.

  FWIW, resolvconf's version is 1.63ubuntu14

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