Filesystem full alarm for additional disks

[DavidePrincipi]

Monitor filesystem free space also for custom disks. Currently only root and boot are checked.

Discussion https://mattermost.nethesis.it/nethesis/pl/a81o8hg4rid87kfztesykrk8aw

[gsanchietti]

The new monitor system uses node_exporter metrics to generate the alerts.
Before proceeding with QA of this issue, please make sure to have installed the latest version from #7162

Test case 1

• Create a fake file to fill the /boot partition: dd if=/dev/zero of=/boot/test bs=1M count=730
• Verify an alert is raised for /boot
• Repeat the test for other filesystems
• Verify the alert is raised for all other filesystems

Example of alert inside journal:

ALERT CRITICAL disk:full:1

[DavidePrincipi]

In testing core 3.5.0-dev.5

[DavidePrincipi]

VERIFIED

curl  -s  http://127.0.0.1:9091/api/v1/alerts | jq

{
  "status": "success",
  "data": {
    "alerts": [
      {
        "labels": {
          "alertname": "disk_full",
          "device": "/dev/vda2",
          "fstype": "xfs",
          "instance": "10.5.4.1:9100",
          "job": "providers",
          "mountpoint": "/boot",
          "node": "1",
          "severity": "warning"
        },
        "annotations": {
          "description": "Disk is almost full (< 10% left)\n  VALUE = 0.0908958708348727\n  LABELS = map[device:/dev/vda2 fstype:xfs instance:10.5.4.1:9100 job:providers mountpoint:/boot node:1]",
          "summary": "Host out of disk space (instance 10.5.4.1:9100)"
        },
        "state": "pending",
        "activeAt": "2025-03-05T10:57:26.180483209Z",
        "value": "9.08958708348727e-02"
      },
      {
        "labels": {
          "alertname": "disk_full",
          "device": "/dev/sda",
          "fstype": "xfs",
          "instance": "10.5.4.1:9100",
          "job": "providers",
          "mountpoint": "/mnt/xvolume_davidep_cluster1_rl4",
          "node": "1",
          "severity": "warning"
        },
        "annotations": {
          "description": "Disk is almost full (< 10% left)\n  VALUE = 0.0939704213689892\n  LABELS = map[device:/dev/sda fstype:xfs instance:10.5.4.1:9100 job:providers mountpoint:/mnt/xvolume_davidep_cluster1_rl4 node:1]",
          "summary": "Host out of disk space (instance 10.5.4.1:9100)"
        },
        "state": "pending",
        "activeAt": "2025-03-05T10:58:26.180483209Z",
        "value": "9.39704213689892e-02"
      }
    ]
  }
}