{ lib, pkgs, config, ... }: # Standard module arguments
{
  services.vmalert.rules.groups = [
    {
      name = "DiskUsageAlerts";
      rules = [
        {
          alert = "HighDiskUsage";
          expr = ''
            (
              node_filesystem_size_bytes{fstype!~"tmpfs|rootfs",mountpoint!=""} - node_filesystem_avail_bytes{fstype!~"tmpfs|rootfs",mountpoint!=""}
            ) / node_filesystem_size_bytes{fstype!~"tmpfs|rootfs",mountpoint!=""} * 100 > 85
          '';
          for = "15m";
          labels = {
            severity = "warning";
            category = "capacity";
          };
          annotations = {
            summary = "High disk usage on {{ $labels.instance }} at {{ $labels.mountpoint }}";
            description = "Disk usage on {{ $labels.instance }} for mount point {{ $labels.mountpoint }} (fstype: {{ $labels.fstype }}) has been above 85% for more than 15 minutes. Current value: {{ $value | printf \"%.2f\" }}%.";
          };
        }
      ];
    }
  ];
}