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:
1#!/bin/bash
2
3BASE_URL="https://uptime.bouni.de/api/push/"
4
5disks=("/dev/sda1")
6alerts=(85)
7urls=("pCDwxPLOoI")
8
9check () {
10 DISK=$1
11 ALERT_LEVEL=$2
12 URL_HASH=$3
13
14 disk_usage=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $5}' | /usr/bin/tr -d "%"`
15 # Get disk space in GB
16 disk_space=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $2}'`
17 # get used disk space in GB
18 used_space=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $3}'`
19 # get free disk space in GB
20 free_space=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $4}'`
21 # get mount point
22 mount_point=`/usr/bin/df -h $DISK | /usr/bin/tail -n +2 | /usr/bin/awk 'END {print $6}'`
23
24 # Check if disk usage is higher than 85%
25 if [ $disk_usage -gt $ALERT_LEVEL ]; then
26 # Send push notification
27 /usr/bin/curl -k --get \
28 --data-urlencode "msg=Disk usage on ${mount_point} is high: ${disk_usage}% (${free_space}/${used_space}/${disk_space})" \
29 --data-urlencode "status=down" \
30 "${BASE_URL}${URL_HASH}"
31 else
32 /usr/bin/curl -k --get \
33 --data-urlencode "msg=Disk usage on ${mount_point} is OK: ${disk_usage}% (${free_space}/${used_space}/${disk_space})" \
34 --data-urlencode "status=up" \
35 "${BASE_URL}${URL_HASH}"
36 fi
37}
38
39for (( i=0; i<${#disks[@]}; i++ )); do
40 check ${disks[$i]} ${alerts[$i]} ${urls[$i]}
41done
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:
1[Unit]
2Description=Sends disk space stats to Uptime Kuma
3
4[Service]
5Type=oneshot
6ExecStart=/opt/scripts/diskspace.sh
And the correspondig systemd timer file:
1[Unit]
2Description=Sends disk space stats to Uptime Kuma
3
4[Timer]
5OnCalendar=*:0/10
6
7[Install]
8WantedBy=timers.target
The result in Uptime Kuma looks like this:
