DHCP provided domain-name not respected while performing name lookups during install

[Russell Weber]

Ubuntu 18.04 is ignoring dhcp provided domain-name for name lookups during install. I suspect that this is also a problem for 19.04 but have not verified the behavior on that build as of yet, but I have also checked the release notes and cannot find anything pertaining to a fix either.

This issue is being spawned from an ask-ubuntu question as I went there first for help. I am filing a bug since I am now satisfied that this has enough information and criteria to fit the description of a confirmed bug.
The question this bug is being cloned from can be found at:
https://askubuntu.com/questions/1139883/18-04-ignoring-dhcp-provided-domain-name-for-name-lookups-during-install

I'm not sure what package this pertains to exactly as I am not sure where the problem is yet since correcting the resolve.conf file in the installer allows the install to continue as it should. However the issue could be in either dhclient it's self or a processed script which is triggered on each new dhcp lease. Either way, it's a pretty serious issue for anyone who has to use local network resources during an install and I hypothesize that this should be a simple fix that should help local installs a great deal.

I could copy the images into the bug, but I'm hoping that isn't needed. There are a lot of images associated with this bug report since it deals with the installer. Those screen shots can be found on the attached askubuntu.com question.

 I ran into the problem while attempting to get a preconfigure file to perform an automated installation of ubuntu. See the following error:
https://i.stack.imgur.com/Ns4qC.png

The preconfigure file is passed in through the kernel parameters in an
ipxe script like so:

    set theKernelParams auto=true fb=false interface=auto priority=critical url=ipxe/ubuntuks.conf

However, this results in an error explaining that we cannot reach the server "ipxe". This is obviously not true from any machine in the lab and even not true from any other operating system that I use ipxe to install.

Further investigation and looking at the console, it would appear that ubuntu is not respecting the dhcp provided domain-name when performing name lookups. This can be seen in the resolve.conf file and the lease made by dhclient. After returning an address from dhcp, dhclient should update the resolve.conf file to allow lookup of names that are not using the FQDN.
screenshot:
https://i.stack.imgur.com/rj68V.png

After correcting the resolve.conf:
https://i.stack.imgur.com/cCyzD.png

Proof that ping works with short names after fixing the resolve.conf:

https://i.stack.imgur.com/JPlkp.png

After making the change to the resolve.conf file.. Setup continues with the preconfigure file like nothing ever happended..

Note: after install resolve.conf shows the following.
https://i.stack.imgur.com/Sz8RL.png

[Russell Weber (rustyscottweber)]

From what I can see, the most likely cluprit is the "dhclient-script".
https://linux.die.net/man/8/dhclient-script
I am out of time, but the installer's "/etc/dhcp/dhclient.conf" file should be checked.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1827640/+editstatus and add the package name in the text box next to the word Package.

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