Every optional collector of the mixin now has alerts, generated only with
that collector enabled in _config.collectors: clock source, disk drive
status, page file usage, license status, scheduled task results, pending
updates, Hyper-V WMI and replication health, failover cluster nodes,
resources, groups and shared volumes, Storage Spaces pool and virtual disk
health, DHCP scope exhaustion and DNS zone transfer failures. The alerts
of the pagefile, diskdrive and license collectors join the memory, disk
and system groups; the other collectors get a group of their own.
New knobs: taskSelector, sharedVolumeSelector, pagefileUsageThreshold,
dhcpScopeFreeWarningThreshold, dhcpScopeFreeCriticalThreshold and
updatePendingDuration. The test configuration enables every optional
collector and tests/optional.test.yaml covers the new alerts.
Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>
