RAID alert implementation

[DavidePrincipi]

A RAID disk failure is an event that must be notified.

Proposed solution

Implement the RAID disk failure alert notification.

See also

• Swap, RAID, Free space, Node alarms #7162
• https://docs.nethserver.org/projects/ns8/en/latest/metrics.html#alerts

[DavidePrincipi]

Test case

With Core 3.7.1, configure alert notification. If a disk in RAID1 fails the alert should be raised and accordingly.

[mrmarkuz]

Test case verified

After mdadm --manage --set-faulty /dev/md127 /dev/sdb2

• The alert is shown in Grafana alert rules
• A notification mail is sent

[DavidePrincipi]

Previously released, now verified https://github.com/NethServer/ns8-core/releases/tag/3.5.0