[Bug 1013843] Re: resolv.conf empty when doing PXE installations

[Thomas Hood]

*** This bug is a duplicate of bug 388060 ***
    https://bugs.launchpad.net/bugs/388060

I just grabbed the Quantal Desktop daily image of 19-Jun-2012  and
extracted the squashfs.

There I found that resolvconf's database contains an
"original.resolvconf" record with "nameserver 10.122.37.1" in it.
Explanation: When resolvconf is installed it puts a copy of the original
resolv.conf file in /etc/resolv.conf.d/original and another copy in
/run/resolvconf/interface/original.resolvconf so that no nameserver
information is lost. The latter file (correctly) disappears at the next
reboot.  I wonder if that file belongs in the live image.

=================BEGIN LOG ================
 # ls -l ./etc/resolv.conf
./etc/resolv.conf -> ../run/resolvconf/resolv.conf
# cd run/resolvconf
# ls -l
total 12
drwxr-xr-x 2 root root 4096 Jun 19 09:39 interface
-r--r--r-- 1 root root    0 Jun 19 09:39 resolv.conf
# ls -l interface
total 12
-r--r--r-- 1 root root 417 Jan 23 20:56 original.resolvconf

# cat interface/original.resolvconf
#
#                                       m   
#  mmmm   m   m  mmmm   mmmm    mmm   mm#mm 
#  #" "#  #   #  #" "#  #" "#  #"  #    #   
#  #   #  #   #  #   #  #   #  #""""    #   
#  ##m#"  "mm"#  ##m#"  ##m#"  "#mm"    "mm 
#  #             #      #                   
#  "             "      "                   
# This file is managed by puppet.  Do not make local changes.

domain buildd
nameserver 10.122.37.1
============== END LOG ==============

Can someone please explain exactly how nameserver and other networking
information is passed from one program to another when booting a live
image, installing Ubuntu on a machine, (apparently) chrooting to the
installed system to run late_command, and rebooting?

A good overview of how live CDs are built would also be helpful to me.

** This bug has been marked a duplicate of bug 388060
   netboot insall of live cd results in a manual network interface configuration

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https://bugs.launchpad.net/bugs/1013843

Title:
  resolv.conf empty when doing PXE installations

Status in “casper” package in Ubuntu:
  New
Status in “resolvconf” package in Ubuntu:
  New
Status in “ubiquity” package in Ubuntu:
  New

Bug description:
  Quantal daily image as of 20110615.
  resolvconf 1.65ubuntu4.

  In our environment we do network installs via PXE booting. We noticed
  that name resolution wasn't working during the late_command phase
  (e.g. any apt-get install operations in the ubiquity/late_command
  fail).

  PXE passes IP information (including DNS) to the kernel, and in this
  case, the entry in /etc/network/interfaces is:

  auto eth0
  iface eth0 inet manual

  What we found is that, with this configuration, /etc/resolv.conf will
  be unconfigured (even though DHCP *did* send DNS information):

  # 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

  if I change the /etc/network/interfaces entry  to

  auto eth0
  iface eth0 inet dhcp

  then I run:

  sudo ifup --force eth0

  then /etc/resolv.conf is populated correctly and DNS resolution starts
  working.

  This would be a regression from Precise, where the resolv.conf file
  gets correctly populated even if the interface is set as manual.

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