Script to check for low disk space on a DigitalOcean volume

check_disk_space.sh

#!/bin/sh
df -H | grep '/mnt/volume-nyc1-01' | awk '{ print $5 " " $1 }' | while read output;
do
  echo $output
  usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1  )
  partition=$(echo $output | awk '{ print $2 }' )
  if [ $usep -ge 80 ]; then
    echo "Running out of space \"$partition ($usep%)\" on $(hostname) as on $(date)"
    curl -s --user "api:$MAILGUN_API_SECRET" \
      https://api.mailgun.net/v3/mastodon.technology/messages \
      -F from='Mastodon Host <root@mastodon.technology>' \
      -F to=ash@ashfurrow.com \
      -F subject="Low Disk Space ($usep%)" \
      -F text="Running out of space on $(hostname) as of $(date)"
  fi
done

crontab

# Note this doesn't work on all distros :shrug:
MAILGUN_API_SECRET='...'
0 * * * * /root/check_disk_space.sh

Based on: https://www.cyberciti.biz/tips/shell-script-to-watch-the-disk-space.html