Following Guix weather.

[Mathieu Othacehe]

Hello,

I have deployed a bunch of changes at https://ci.guix.gnu.org/. I'd like
to introduce some of them here.

First, there are some new specifications: "images", "tarball" and
"tests".  Those specifications are configured to build respectively, the
%guix-system-images declared in (gnu ci), the Guix binary tarball and
the Guix System tests.

Each Guix commit potentially triggers a rebuilt of all those
specifications. We have previously established that this is too resource
consuming.

That's why I have added a "period" field to the specification
definition.  This field only allows a new evaluation when at least X
seconds have elapsed since the last evaluation.  Right now, the three
aforementioned specifications have a period field set to 86400 seconds
(24 hours).

I have also improved the visibility of latest state of a
specification. For instance, if you want to know what's the current
status of the "master" branch or the "staging" branch, you will find
some statistics directly on the home page. For a more detailed view, you
can consult dashboards for each specification.

master dashboard: https://ci.guix.gnu.org/eval/19534/dashboard
staging dashboard: https://ci.guix.gnu.org/eval/19488/dashboard
test dashboard: https://ci.guix.gnu.org/eval/19464/dashboard

By having a look at those dashboards, it's obvious that we still have a
lot of work before all those circles turn to green.

Finally, in the evaluation view there's a "Toggle" button to switch
between:

- The number of newly fixed/broken/pending builds for each evaluation
  (default)
- The total number of fixed/broken/pending builds for each evaluation.

Don't hesitate to comment on those new features :)

Thanks,

Mathieu