The automatic transfer switch does not seem to work reliably when both
UPS sources are running on battery. This means all systems lose power
after the first UPS battery dies, even though the second UPS is still
online. To minimize the risk of data loss, at least until I figure out
what's wrong, I want both VM hosts to shut down as soon as the first UPS
signals that its battery is low.
`upsmon` is the component of [NUT] that monitors (local or remote) UPS
devices and reacts to changes in their state. Notably, it is
responsible for powering down the system when there is insufficient
power to the system.
Transitioning from push-based to pull-based monitoring with
Prometheus/collectd. The *write_prometheus* plugin will be installed on
all hosts, and Prometheus will be configured to scrape them directly.
*vmhost0.pyrocufflink.blue* no longer uses `dhcpcd` for network
configuration, but *systemd-networkd*.
The host-specific network settings for a VM host include the
configuration for the management interface, as well as the configuration
of the physical ports that make up the bonded interfaces.
The VM hosts have multiple network interfaces with IPv6 addresses, so
collectd may not always choose the correct one to send metrics. Thus we
have to explicitly tell it to use the management interface, to avoid it
sending data on the SAN interface.
Dustin