What is the best and easy way (and free) to get automated alerts if the computer i am running node-red is for some reason offline ?
I have set up the PC, to reboot automatically after a power failure and node red starts as a windows service automatically.
I need some mechanism where i can get an email or a telegram alert, if for some reason either the PC not restarts or NR doesn't start.
is my expectation too un realisitc ? especially for free ?
This implies that your alert generator is on another PC.
I use a free online service at https://healthchecks.io/
One of my flows calls an api at that site every 10mins.
If that call is not detected after a selectable time, then that web site will send me a message. I have messages over email and telegram, but there are a selection of other communication methods available.
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You could use the Last Will & Testament (LWT) feature of MQTT.
Of course you need an MQTT broker and another device to subscribe to the birth, close and will messages. That could be a Raspberry Pi Zero 2, itself running Node-red (and maybe the MQTT broker too), so not free but not very expensive.
Unfortunately I don't know how gracefully the PC would disconnect from the broker if you do a shutdown, but the Pi should receive either the close or will message after about 30sec offline, then it can send email, telegram or other alerts.
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Here's a simple NR flow that makes use of HealthChecks (HC).
Just sign-up for a FREE HC account - no credit card needed.
Get the Ping URL and insert it in the http-request node.
Set the timings to suit your application/needs.
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I know your running windows but for the Linux users
I run node-red thru pm2 which watchdogs it and restarts if crashes or zombies
I have never had any downtime doing it this way.
I think you can get pm2 to alert if it does something.. I dont use that feature thou
That would not help if the PC did not start up.
You need to think about failure modes:
- The Node-RED server (hardware/OS)
- The Node-RED service
Possibly, you might also need to think about Wi-Fi, router and broadband connections. Depending on your needs.
Monitoring the service is relatively easy, you need some kind of watchdog that will be able to send an alert on failure. MQTT ideally on a different device with a ping flow that has an LWT defined and perhaps its own Node-RED running with just a telegram bot flow. I use Telegraf as a system monitor that outputs data not only to InfluxDB for historic records but also to MQTT for immediate notifications.
You could, of course write a separate service using node.js or Python rather than Node-RED. Might also be a better solution if you don't use MQTT.
Of course, if your building power goes out, this might not be enough. You could allow a single endpoint to be accessible that was a simple ping API. In fact, if you use Cloudflare Zero Trust, it will monitor your connections and alert you if it goes down (via email), their free tier is very generous. If you are running Node-RED on a Windows PC, try their Cloudflare WARP client as that also has notifications built in, you don't even need to set up an active endpoint, just have the client running.
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