Actions

Glances can trigger actions on events for warning and critical thresholds.

By action, we mean all shell command line. For example, if you want to execute the foo.py script if the last 5 minutes load are critical then add the _action line to the Glances configuration file:

[load]
critical=5.0
critical_action=python /path/to/foo.py

All the stats are available in the command line through the use of the Mustache syntax. Chevron is required to render the mustache’s template syntax.

Additionaly to the stats of the current plugin, the following variables are also available: - {{time}}: current time in ISO format - {{critical}}: critical threshold value - {{warning}}: warning threshold value - {{careful}}: careful threshold value

Another example would be to create a log file containing used vs total disk space if a space trigger warning is reached:

[fs]
warning=70
warning_action=python /path/to/fs-warning.py {{mnt_point}} {{used}} {{size}}

Note

For security reasons, the command line is split into arguments before the Mustache fields are rendered. Each field therefore always produces exactly one argument, whatever its value contains: a value holding spaces, quotes or shell operators can neither split itself into several arguments nor inject new ones into the invoked process.

Two consequences:

Quoting a Mustache field is unnecessary. script.sh {{mnt_point}} passes a mount point containing spaces as a single argument. Quoting it (script.sh "{{mnt_point}}") is harmless but no longer needed.
A Mustache section must open and close within the same argument. {{#cmdline}}{{.}},{{/cmdline}} is valid; {{#cmdline}}{{.}} {{/cmdline}} is not, and the action is not executed (an error is logged).

A field that renders to an empty string still produces an empty argument, so an empty value never shifts the positional arguments of the invoked script.

Mustache-rendered values are also sanitized as defence in depth: the characters &&, |, > and >> are replaced by spaces.

As a consequence, shell operators (pipes, redirections, command chaining) cannot be used inside a Mustache value. They keep working when you write them in the command line itself. If your action requires operators driven by the stats, write a shell script and call it from the action instead.

For example, to create a log file containing the total user disk space usage for a device and notify by email each time a space trigger critical is reached, create a shell script /etc/glances/actions.d/fs-critical.sh:

#!/bin/bash
# Usage: fs-critical.sh <time> <device_name> <percent>
echo "$1 $2 $3" > /tmp/fs.alert
python /etc/glances/actions.d/fs-critical.py

Then reference it in the configuration file:

[fs]
critical=90
critical_action_repeat=/etc/glances/actions.d/fs-critical.sh {{time}} {{device_name}} {{percent}}

Within /etc/glances/actions.d/fs-critical.py:

import subprocess
from requests import get

fs_alert = open('/tmp/fs.alert', 'r').readline().strip().split(' ')
device = fs_alert[0]
percent = fs_alert[1]
system = subprocess.check_output(['uname', '-rn']).decode('utf-8').strip()
ip = get('https://api.ipify.org').text

body = 'Used user disk space for ' + device + ' is at ' + percent + '%.\nPlease cleanup the filesystem to clear the alert.\nServer: ' + str(system)+ '.\nIP address: ' + ip
ps = subprocess.Popen(('echo', '-e', body), stdout=subprocess.PIPE)
subprocess.call(['mail', '-s', 'CRITICAL: disk usage above 90%', '-r', 'postmaster@example.com', 'glances@example.com'], stdin=ps.stdout)

Note

You can use all the stats for the current plugin. See https://github.com/nicolargo/glances/wiki/The-Glances-RESTFUL-JSON-API for the stats list.

It is also possible to repeat action until the end of the alert. Keep in mind that the command line is executed every refresh time so use with caution:

[load]
critical=5.0
critical_action_repeat=/home/myhome/bin/bipper.sh