Integrating Django application metrics into Zabbix

At Tangent, we use Zabbix for monitoring and alerting. This is a note-to-self on how to configure application monitoring.

Management command

You need a script that prints out a value to STDOUT. A simple management command suffices:

from django.core.management.base import BaseCommand, CommandError

class Command(BaseCommand):

    def handle(self, *args, **options):
        if not args:
            print self.usage()
            return
        method_name = 'fetch_%s' % args[0]
        if not hasattr(self, method_name):
            raise CommandError("No method found with name '%s'" % method_name)
        print getattr(self, method_name)(*args[1:])

    def usage(self):
        fetchers = [m for m in dir(self) if m.startswith('fetch')]
        descriptions = []
        for fetcher in fetchers:
            method = getattr(self, fetcher)
            docstring = method.__doc__.strip() if method.__doc__ else "<no description>"
            descriptions.append(" - %s : %s" % (
                fetcher.split("_")[1], docstring))
        return "Available fetchers:\n%s" % "\n".join(descriptions)

This uses dynamic dispatch to call “fetcher” methods with name fetch_%s where the first argument defines the format variable. Eg, a method:

def fetch_num_users(self):
    """
    Fetch number of users
    """
    return User.objects.all().count()

is called via:

$ ./manage.py application_metric num_users

Without arguments, a list of fetchers is shown:

$ ./manage.py application_metric
Available fetchers:
 - num_users : Fetch number of users

It’s trivial to add more fetch_* methods to emit additional metrics.

Zabbix plugin

Hook this up to Zabbix by first creating a plugin script which calls the management command, passing on an arg:

$ cat /etc/zabbix/plugins/application
#!/bin/bash

source /path/to/virtualenv/bin/activate && /path/to/project/manage.py application_metric $1

then create the Zabbix “UserParameter” declaration which calls the plugin script:

$ cat /etc/zabbix/zabbix_agentd.conf.d/application.conf
UserParameter=application[*],/etc/zabbix/plugins/application $1

The application[*] syntax means that you can configure various “Items” in Zabbix like application[num_orders] and application[num_users] and the bracketed string will get passed all the way through to the management command.

Now restart Zabbix to pick up the new conf file:

$ /etc/init.d/zabbix-agent restart

Zabbix dashboard

In the Zabbix web dashboard add new “Items” that use this new “UserParameter”. Add a new “Item” by navigating through Configuration > Hosts > Items > Create item. In the resulting form, set the “Key” to, say, application[num_users] to pass num_users as the first argument through to the management command.

And that’s it: this metric will now be collected by Zabbix and can be used for graphing and alerting.

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Tagged with: django, monitoring
Filed in: tips

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