*collectd* logs to syslog, so its output is lost when it's running in a
container. We can capture messages from it by mounting the journald
syslog socket into the container.
Even with *collectd* configured to report filesystem usage by device, it
still only reports filesystems that are mounted (in its namespace).
Thus, in order for it to report filesystems like `/boot`, these need to
be mounted in the container.
I keep going back-and-forth on whether or not collectd should run in a
container on Fedora CoreOS machines. On the one hand, running it
directly on the host allows it to monitor filesystem usage by mount
point, which is consistent with how non-FCOS machines are monitored.
On the other hand, installing packages on FCOS with `rpm-ostree` is a
nightmare. It's _incredibly_ slow. There's also occasionally issues
installing packages if the base layer has not been updated in a while
and the new packages require an existing package to be updated.
For the NUT server specifically, I have changed my mind again: the
*collectd-nut* package depends on *nut-client*, which in turn depends on
Python. I definitely want to avoid installing Python on the host, but I
do not want to lose the ability to monitor the UPSs via collectd. Using
a container, I can strip out the unnecessary bits of *nut-client* and
avoid installing Python at all. I think that's worth having to monitor
filesystem usage by device instead of by mount point.
Dustin