[Bug 1770557] [NEW] systemd-resolved should be restarted only on actual DHCP/DNS updates

[Wladimir Mutel]

Public bug reported:

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

** Affects: systemd (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1770557

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

Status in systemd package in Ubuntu:
  New

Bug description:
  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

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