use dhclient -4 instead of ipconfig in easy cases in 18.10

[Steve Langasek]

When adding ipv6 netboot support to initramfs-tools in yakkety/zesty, this was initially attempted with replacing ipconfig with dhclient. As described in LP: #1621507, the use of dhclient for ipv4 dhcp was backed out in favor of ipconfig. So at the moment, we are using both ipconfig from klibc-utils and dhclient from isc-dhcp-client in the initramfs.

We want to switch off of klibc-utils completely and use isc-dhcp-client for both ipv4 and ipv6 in initramfs-tools. But for cosmic, we'll only do the easy bits. Bug 1790418 is about finishing the job.

[Michael Hudson-Doyle (mwhudson)]

I'm not sure I see a path to switching away from klibc-utils completely. As far as I can tell, every upload of initramfs-tools ever has still invoked ipconfig for some arguments.

Most configs can be handled by writing some shell to replace what ipconfig does and some functionality can probably be dropped but doing all of it doesn't sound like a lot of fun.

It would be fairly easy to invoke dhclient for the common case of a simple dhcp request, but would it be worth it?

[Steve Langasek (vorlon)]

Which cases were still using ipconfig and why? Can you point to the exact upload you're looking at?

[Michael Hudson-Doyle (mwhudson)]

Well there are quite a few uploads to choose from, but this one https://git.launchpad.net/ubuntu/+source/initramfs-tools/tree/scripts/functions?id=import/0.125ubuntu6#n339 is about the least "ipconfig-y" and it still calls it sometimes...

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Kenyon Ralph (kralph)]

This can be closed since bug 2024164 replaced dhclient with dhcpcd.

[Benjamin Drung (bdrung)]

As mentioned in bug #1790418 there is still one call to ipconfig that hasn't been replaced (as of initramfs-tools 0.142ubuntu19 in noble).