monitoring: kuma heartbeat + systemd timer for zigbee coordinator

Refs #3

.gitignore

@@ -1,2 +1,5 @@
 output/
 secrets.h
+
+# zigbee coordinator -> uptime kuma push token
+infra/.secrets/

infra/systemd/zigbee-kuma-heartbeat.service

@@ -0,0 +1,8 @@
+[Unit]
+Description=Zigbee coordinator heartbeat to Uptime Kuma
+After=docker.service
+Requires=docker.service
+
+[Service]
+Type=oneshot
+ExecStart=/root/nr-flow-validator/infra/zigbee2mqtt/scripts/kuma-heartbeat.sh

infra/systemd/zigbee-kuma-heartbeat.timer

@@ -0,0 +1,10 @@
+[Unit]
+Description=Run zigbee coordinator heartbeat every minute
+
+[Timer]
+OnCalendar=*-*-* *:*:00
+AccuracySec=5s
+Persistent=true
+
+[Install]
+WantedBy=timers.target

infra/zigbee2mqtt/scripts/kuma-heartbeat.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+set -u
+
+KUMA_BASE="https://up.notsosm.art"
+TOKEN_FILE="/root/nr-flow-validator/infra/.secrets/kuma-push-token"
+
+[ -s "$TOKEN_FILE" ] || exit 1
+TOKEN="$(tr -d '[:space:]' < "$TOKEN_FILE")"
+
+reason=""
+
+state=$(docker exec mosquitto mosquitto_sub -h 127.0.0.1 -t "zigbee2mqtt/bridge/state" -C 1 -W 10 2>/dev/null | tr -d '[:space:]')
+if [ "$state" != '{"state":"online"}' ]; then
+    reason="bridge_state=${state:-none}"
+else
+    running=$(docker inspect zigbee2mqtt --format '{{.State.Running}}' 2>/dev/null)
+    [ "$running" = "true" ] || reason="${reason}container_running=${running:-unknown}"
+fi
+
+if [ -n "$reason" ]; then
+    status="down"
+    msg="coordinator: ${reason}"
+else
+    status="up"
+    msg="coordinator ok"
+fi
+
+curl -fsS -m 10 -o /dev/null "$KUMA_BASE/api/push/$TOKEN?status=$status&msg=$msg" 2>/dev/null
+exit 0