On Sun, May 08, 2022 at 11:24:12AM -0400, Michael Stone wrote:
I've been trying to make sense of the NEWS item in isc-dhcp-client (that
alternatives are needed) in combination with the functionality of ifupdown
and what the implications are for debian upgrades generally.
isc-dhcp-client as of the last upgrade is telling users to stop using it
(the default dhcp client for debian).
ifupdown (the traditional tool for managing networking on debian systems)
has a Recommends on "isc-dhcp-client | dhcp-client". "dhcp-client" is a
virtual package provided by "dhcpcanon" (version 0.8.5, which hasn't been
touched in 4 years), "isc-dhcp-client", and "dhcpcd5" (which will trash a
working configuration managed by ifupdown if installed, as it will try to
take over interfaces currently set, e.g., to manual). This seems suboptimal
at best.
I believe that ifupdown will attempt to use udhcpd if installed, which
should be a mostly-transparent change (except for the potential loss of
lease information and any customization of dhclient scripts) but it isn't
even on the ifupdown recommends list.
ifupdown also (used to?) use pump, but that package went away a long time
ago.
So what's the path forward, maintaining compatibility and not breaking
systems upgrading from current stable? Do we come up with a dhcpcd5 variant
that *only* touches interfaces it is directed to touch via
/etc/network/interfaces? Do we add udhcpcd to the "dhcp-client" virtual
package and/or make it the default for ifupdown? Do we fork isc's dhcp suite
and just continue to use dhclient? Revive pump? Something else?
Not an answer to your question, but a related issue I'll mention here.
Ubuntu no longer uses isc-dhcp by default, because it no longer uses
ifupdown; NetworkManager and networkd both have their own implementations of
dhcp clients which are used by preference. *However*, isc-dhcp is still
installed as part of all Ubuntu systems, because it is the only client
implementation that integrates with initramfs-tools
(/usr/share/initramfs-tools/hooks/zz-dhclient) so if you are using nfsroot
or any other network-based rootfs, it appears to still be the only game in
town. It would be a good idea to make sure as part of the deprecation of
isc-dhcp-client that we get initramfs integration of whatever is the
preferred replacement.