CI status

[Mathieu Othacehe]

Hello,

You must have noticed that the CI is currently struggling a bit. Here is
a small recap of the situation.

* The IO operations on Berlin are mysteriously slow. Removing files from
  /gnu/store/trash is taking ages. This is reported here:
  https://issues.guix.gnu.org/51787.

  We have to kill the garbage collect frequently to keep things
  going. The bad side is obviously that we can't do that forever, as we
  only have 9.3T and decreasing, while we aim to stay at 10T available.

* The PostgreSQL database behind ci.guix.gnu.org also became super slow
  and I decided to drop it. I don't know if there's a connection with
  the above point. I'm missing the appropriate tools/knowledge to
  monitor the IO & file-system performances.

* The php package isn't building anymore, reported here:
  https://issues.guix.gnu.org/52513. This means that we cannot
  reconfigure zabbix. I removed it from the berlin configuration
  temporarily.
  
* The cuirass-remote-server Avahi service is no longer visible when
  running "avahi-browse -a". I strongly suspect that this is related to
  the static-networking update, even if I don't have a proof for
  now. This means that the remote-workers using Avahi for discovering
  (hydra-guix-*) machines can no longer connect. The
  ci.guix.gnu.org/workers list is thus quite empty.

* Facing those problems, I tried to rollback to a previous system
  generation, but this is bringing even more issues, as for instance the
  older Cuirass package, is struggling with the new database structure and
  other niceties. I think out best course of action is to stick to
  master and fix the above problems.

Thanks,

Mathieu