I use Uptime Kuma as my self hosted monitoring solution and it worked perfectly find so far. But every now an then I run out of disk space on my Hetzner cloud server because they have only 15G in the smallest variant.
Thats very annoing but on the other hand I hesitate to run a full blown monitoring solution.
So today I realized that Uptime Kuma now has the ability to add a so called passive monitor where it does not actively ping a resource but receive a request.
That allows me to monitor the disk space with a sript that gets called by a systemd timer every 10 minutes.
Here’s the script I came up with:
#!/bin/bash
BASE_URL="https://uptime.bouni.de/api/push/"
disks=("/dev/sda1")
alerts=(85)
urls=("pCDwxPLOoI")
check () {
DISK=$1
ALERT_LEVEL=$2
URL_HASH=$3
disk_usage=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $5}' | /usr/bin/tr -d "%"`
# Get disk space in GB
disk_space=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $2}'`
# get used disk space in GB
used_space=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $3}'`
# get free disk space in GB
free_space=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $4}'`
# get mount point
mount_point=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $6}'`
# Check if disk usage is higher than 85%
if [ $disk_usage -gt $ALERT_LEVEL ]; then
# Send push notification
/usr/bin/curl -k --get \
--data-urlencode "msg=Disk usage on ${mount_point} is high: ${disk_usage}% (${free_space}/${used_space}/${disk_space})" \
--data-urlencode "status=down" \
"${BASE_URL}${URL_HASH}"
else
/usr/bin/curl -k --get \
--data-urlencode "msg=Disk usage on ${mount_point} is OK: ${disk_usage}% (${free_space}/${used_space}/${disk_space})" \
--data-urlencode "status=up" \
"${BASE_URL}${URL_HASH}"
fi
}
for (( i=0; i<${#disks[@]}; i++ )); do
check ${disks[$i]} ${alerts[$i]} ${urls[$i]}
done
At the top are three arrays in which I configure the disk device, the alert level and the hash from the Uptime Kuma push URL for each disk I want to be monitored.
The script then loop over all configured disks, gets the data for that disk, compares the free space to a threshold and sends the right request to my uptime instance.
By setting the GET parameter status to either up or down I decide if everything is still fine or not.
It even allows to have a custom message for the logs using the msg parameter.
The systemd service file looks like this:
[Unit]
Description=Sends disk space stats to Uptime Kuma
[Service]
Type=oneshot
ExecStart=/opt/scripts/diskspace.sh
And the correspondig systemd timer file:
[Unit]
Description=Sends disk space stats to Uptime Kuma
[Timer]
OnCalendar=*:0/10
[Install]
WantedBy=timers.target
The result in Uptime Kuma looks like this:
