How to monitor the size of a directory via Telegraf

You could create a simple bash script metrics-exec_du.sh with the following content (chmod 755):

#!/usr/bin/env bash
du -bs "${1}" | awk '{print "[ { \"bytes\": "$1", \"dudir\": \""$2"\" } ]";}'

And activate it by putting the following in the Telegraf config file:

[[inputs.exec]] commands = [ "YOUR_PATH/metrics-exec_du.sh /var/lib/influxdb/data" ] timeout = "5s" name_override = "du" name_suffix = "" data_format = "json" tag_keys = [ "dudir" ]

Caveats:

1. The du command can stress your server, so use with care
2. The user telegraf must be able to scan the dirs. There are several options, but since InfluxDB's directory mask is a bit unspecified (see: https://github.com/influxdata/influxdb/issues/5171#issuecomment-306419800), we applied a rather crude workaround (examples are for Ubuntu 16.04.2 LTS):
   • Add the influxdb group to the user telegraf : sudo usermod --groups influxdb --append telegraf
   • Put the following in the crontab, run for example each 10 minutes: 10 * * * * chmod -R g+rX /var/lib/influxdb/data > /var/log/influxdb/chmodfix.log 2>&1

Result, configured in Grafana (data source: InfluxDB):

Cheers, TW

If you need to monitor multiple directories I updated the answer by Tw Bert and extended it to allow you to pass them all on one command line. This saves you having to add multiple [[input.exec]] entries into your telegraf.conf file.

Create the file /etc/telegraf/scripts/disk-usage.sh containing:

#!/bin/bash

echo "["
du -ks "$@" | awk '{if (NR!=1) {printf ",\n"};printf "  { \"directory_size_kilobytes\": "$1", \"path\": \""$2"\" }";}'
echo
echo "]"

I want to monitor two directories: /mnt/user/appdata/influxdb and /mnt/user/appdata/grafana. I can do something like this:

# Get disk usage for multiple directories
[[inputs.exec]]
  commands = [ "/etc/telegraf/scripts/disk-usage.sh /mnt/user/appdata/influxdb /mnt/user/appdata/grafana" ]
  timeout = "5s"
  name_override = "du"
  name_suffix = ""
  data_format = "json"
  tag_keys = [ "path" ]

Once you've updated your config, you can test this with:

telegraf --debug --config /etc/telegraf/telegraf.conf --input-filter exec --test

Which should show you what Telegraf will push to influx:

bash-4.3# telegraf --debug --config /etc/telegraf/telegraf.conf --input-filter exec --test
> du,host=SomeHost,path=/mnt/user/appdata/influxdb directory_size_kilobytes=80928 1536297559000000000
> du,host=SomeHost,path=/mnt/user/appdata/grafana directory_size_kilobytes=596 1536297559000000000