There's a few rabbitmq metrics that haven't been pulled into prometheus but
they shouldn't be too hard to add[9,10] (currently, we mostly use the real-time
dashboard[11] anyway, so there wouldn't be any functionality regression).

[9] https://github.com/kbudde/rabbitmq_exporter
[10] aha, no Debian package yet.
[11] http://saatchi.internal.softwareheritage.org:15672/