Bug#1025062: systemd-resolved Provides: resolvconf, but is missing the isc-dhcp-client integration from resolvconf

[Helmut Grohne]

Package: systemd-resolved,isc-dhcp-client

Hi,

When systemd-resolved started replacing and providing resolvconf, things
looked good, but isc-dhcp-client no longer propagates DNS servers to
resolved. This used to work when resolvconf and systemd-resolved were
coinstallable and one used resolvectl to implement resolvconf. The crux
is that resolvconf contains the integration scripts that make
isc-dhcp-client run resolvconf even when resolvconf is provided by
systemd-resolved. Now that systemd-resolved conflicts with resolvconf,
it broke that integration, which is bad.

I briefly talked to Michael about this and he figured that we wouldn't
want to go through the extra resolvconf layer and rather do things
directly. Indeed, this is what has happened for ifupdown already.
ifupdown now contains /etc/network/if-*.d/resolved and integrates
directly. NetworkManager does it directly likewise. isc-dhcp-client
should likely do it as well.

Thus I think a good solution to this bug would be:
 * isc-dhcp-client ships scripts to directly integrate with resolved.
 * systemd-resolved Breaks isc-dhcp-client in versions that don't
   integrate.
 * resolvconf no longer participates in propagating DNS servers from
   isc-dhcp-client to systemd-resolved. Neither on the interface level
   nor on the package level.

Does that make sense?

Workaround: One can manually place the previous resolvconf script from
https://sources.debian.org/src/resolvconf/1.91%2Bnmu1/etc/dhcp/dhclient-enter-hooks.d/resolvconf/

Helmut