systemd-resolved should be restarted only on actual DHCP/DNS updates

[Wladimir Mutel]

My ISP gives me a DHCP IP with lease time about 2 minutes
in the script /etc/dhcp/dhclient-enter-hooks.d/resolved , a function make_resolv_conf is defined which creates config fragments in resolved.conf.d/ , then unconditionally restarts systemd-resolved service
so, about every 2 minutes, this service is restarted on my system, despite the fact that DNS configuration is not changed.
I would propose an update to the script, which first creates config fragments in temporary files, and then it restarts the service only when config is changed (or created/removed).
now going to attach my patch below

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "resolved.patch" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

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[Dimitri John Ledkov (xnox)]

Very nice! I'm sorry you hit this problem, and your analysis and solution look good. I will work on integrating it.

[Wladimir Mutel (mwg)]

well, this fix is related only to isc-dhcp-client whose functionality is replaced with systemd-networkd. so, don't know how relevant it is going to be

[Dan Streetman (ddstreet)]

please reopen if this is still an issue