Creating a Custom Alert

[terminal addict]

There may be other (proper?) ways of doing this. If so, wonderful! If not, this is for you. :)

Would you like to issue your own custom alert (http://doc.freenas.org/index.php/Alert)? Well, the alert scripts are pretty straightforward. Here is a script that watches for the existence of the file /tmp/my_alert. The first line of /tmp/my_alert can optionally set the alert to either WARN or CRIT.

Code:

import os
 
from freenasUI.system.alert import alertPlugins, Alert, BaseAlert
 
 
class MyAlert(BaseAlert):
 
    def run(self):
        my_alert_type = Alert.WARN
        my_alert_msg = "my_alert has triggered an alert"
        if os.path.exists('/tmp/my_alert'):
            with open ("/tmp/my_alert", "r") as alertfile:
                my_alert_data=alertfile.readlines()
 
                if len(my_alert_data) == 1:
                    my_alert_msg = my_alert_data[0].rstrip('\n')
                elif len(my_alert_data) > 1:
                    if my_alert_data[0] == 'WARN\n':
                        my_alert_type = Alert.WARN
                    elif my_alert_data[0] == 'CRIT\n':
                        my_alert_type = Alert.CRIT
                    my_alert_msg = my_alert_data[1].rstrip('\n')
 
                return [
                    Alert(
                        my_alert_type,
                        my_alert_msg
                    ),
                ]
 
alertPlugins.register(MyAlert)

Copy and save to /usr/local/www/freenasUI/system/alertmods/my_alert.py. Don't forget to mount the filesystem for writing first (mount -uw /). I would recommend a reboot after adding the script so that it is registered in the web GUI. A reboot will also return the root filesystem to read-only. Might be other ways to do this, but I found this method the easiest.

Why use this? Well, if you have a cronjob monitoring something specific, it can create the /tmp/my_alert file. Note that CRIT alerts will send emails to the root email account. WARN alerts do not, but the alert icon will blink yellow.

Edit: Title should have been Creating a Custom Alert. Ugh. Need sleep.
Edit 2: Thanks for the edits/fixes! :)

 

[cyberjock]

Fixed the title for you.

 

[joeschmuck]

Fixed your link too.