Uptime monitoring for OpenWrt and Unraid

I have been using Uptime Kuma for quite some to monitor some services, and I wanted to add the following health checks:

I tend to use Push monitoring whenever I can, as it doesn’t need to accept ingress connections for private networks, and it does involve less moving parts. The easiest way would be to setup a simple cron on both systems.

OpenWrt Push Monitor

You will need ssh access to your OpenWrt router. If you don’t, you should generate a new key pair with the command:

ssh-keygen -t rsa

You can then set your public key through your router’s LuCI web interface, by appending its content in System → Administration.

You will then be able to ssh as root using:

ssh -oHostKeyAlgorithms=+ssh-rsa -i '<public_key_path>' root@<router_ip>

With that out of the way, let’s add a simple cron to call our Push URL every minute. To edit your crontab, run crontab -e and then add the following line:

* * * * * wget --spider "https://<your_push_url>" >/dev/null 2>&1*

There should be a EOL character on the last line of the crontab file, just leave an empty line at the end to be sure. Now restart the cron service in order for the changes to take effect:

service cron restart

This will keep calling the Push URL every minute.

Unraid Push Monitor

Adding a push monitor to Unraid is similar, but we will use a plugin instead of the command line, otherwise any changes won’t be persisted between reboots.

  1. Install the CA Uer Scripts plugin if you haven’t already
  2. Go to Settings → User Scripts → Add New Script
  3. Edit the script by adding wget --spider "https://<your_push_url>" >/dev/null 2>&1*
  4. Set the schedule as Custom, and type * * * * * to call the URL every minute

Bonus: Other devices

I also wanted to monitor internet connectivity on a router which doesn’t support OpenWRT. In this case, I opted for a simple sketch I put together on a M5Atom ESP32 device which connects to the Wi-Fi network and repeatedly call the Push URL, and as the modem has an USB port, I am powering the ESP32 directly from there.