Add disk usage check for Kuma pushes

kuma-checks.json

@@ -27,5 +27,12 @@
         "type": "mount",
         "target": "/mnt/media",
         "push": "xxxxxxxxxxxxxxxx" 
+    },
+    {
+        "name": "root_disk",
+        "type": "disk",
+        "target": "vda5",
+        "threshold": 85,
+        "push": "xxxxxxxxxxxxxxxx" 
     }
 ]

kuma-push.sh

@@ -32,6 +32,40 @@ check_http() {    # arg: URL
 check_service() { systemctl is-active --quiet "$1" && echo "up 0" || echo "down 0"; }
 check_docker()  { docker inspect -f '{{.State.Running}}' "$1" &>/dev/null && echo "up 0" || echo "down 0"; }
 check_mount()   { mountpoint -q "$1" 2>/dev/null && echo "up 0" || echo "down 0"; }
+check_disk() {
+  # args: device (e.g. sda, /dev/vda5) and threshold percentage
+  local raw_target="$1" threshold="$2" dev mount usage
+
+  if [[ -z "$threshold" || ! "$threshold" =~ ^[0-9]+$ ]]; then
+    echo "down 0"
+    return 0
+  fi
+
+  if [[ "$raw_target" == /dev/* ]]; then
+    dev="$raw_target"
+  else
+    dev="/dev/$raw_target"
+  fi
+
+  if ! mount=$(findmnt -nr -S "$dev" -o TARGET 2>/dev/null); then
+    echo "down 0"
+    return 0
+  fi
+
+  usage=$(df --output=pcent "$mount" 2>/dev/null | awk 'NR==2 {gsub(/%/, ""); print $1}') || true
+
+  if [[ -z "$usage" ]]; then
+    echo "down 0"
+    return 0
+  fi
+
+  if (( usage >= threshold )); then
+    echo "down $usage"
+  else
+    echo "up $usage"
+  fi
+}
+
 check_native()  { echo "up 0"; }
 
 # --------------------------------------------------------------------------- #
@@ -41,12 +75,14 @@ jq -c '.[]' "$CFG" | while IFS= read -r item; do
   type=$(jq -r '.type'            <<<"$item")
   id=$(jq   -r '.push'            <<<"$item")
   tgt=$(jq  -r '.target // empty' <<<"$item")   # target may be absent
+  thr=$(jq  -r '.threshold // empty' <<<"$item")
 
   case "$type" in
     http)    read -r stat ping < <(check_http    "$tgt") ;;
     service) read -r stat ping < <(check_service "$tgt") ;;
     docker)  read -r stat ping < <(check_docker  "$tgt") ;;
     mount)   read -r stat ping < <(check_mount   "$tgt") ;;
+    disk)    read -r stat ping < <(check_disk    "$tgt" "$thr") ;;
     native)  read -r stat ping < <(check_native)         ;;
     *)       stat=down ping=0 ;;
   esac