Our users tell us all the time: The AppDynamics platform is amazing right out of the box. But everybody has something special they want to do, whether it’s to add some functionality, set up a unique monitoring scenario, whatever. That’s what makes AppDynamics’ emphasis on open architecture so important and useful. The functionality of the AppDynamics machine agent can be customized and extended to perform specific tasks to meet specific user needs, either through existing extensions from the AppDynamics Exchange or through user customizations.

It helps to understand what the machine agent is and how it works. The machine agent is a stand-alone java application that can be run in conjunction with application agents or separate from them. This means monitoring can be extended to environments outside the realm of the application being monitored. It can be deployed to application servers, databases servers, web servers — really anything running Linux, UNIX, Windows, or MAC.

The real elegance of the machine agent is its tremendous extensibility. For non-Windows environments, there are three ways to extend the machine agent: through a script, with Java, or by sending metrics to the agent’s HTTP listener. If you have a .NET environment, you also have the capability of adding additional hardware metrics, over and above these three ways.

Let’s look at a real-life example. Say I want to create a extension using cURL that would give the HTTP status of certain websites. My first step is to look for one in the AppDynamics Exchange, our library of all the extensions and integrations currently available. It’s also the place one can request extensions that they need or submit extensions they have built.

Sure enough, there’s one already available (community.appdynamics.com/t5/AppDynamics-eXchange/idbp/extensions) called Site Monitor, written by Kunal Gupta. I decided to use it, and followed these steps to create my HTTP status collection functionality.

1. Download the extension to the machine agent on a test machine.
2. Edit the Site Monitor configuration file (site-config.xml) to ping the sites that I wanted (in this case www.appdynamics.com). The sites can also be HTTPS sites if needed.
3. Restart the machine agent.

That’s it. It started pulling in the status code right away and, as a bonus, also the response time for requesting the status code of the URL that I wanted.

It’s great that I can now see the status code (200 in this case), but now I can truly use its power. I can quickly build dashboards displaying the information.

There also is the ability to hook the status code into custom health rules, which provide alerts when performance becomes unacceptable.

So there it is. In just a matter of minutes, the extension was up and running, giving me valuable data about the ongoing status of my application. If the extension that I wanted didn’t exist, it would have been just as easy to use the cURL command (curl –sL –w “{http_code} \\n “ www.appdynamics.com -o /dev/null).

Either way, the machine agent can be extended to support your specific needs and solve specific challenges. Check out the AppDynamics Exchange to see what kinds of extensions are already available, and experiment with the machine agent to see how easily you can expand its capabilities.

If you’d like to try AppDynamics check out our free trial and start monitoring your apps today!

The post The Incredible Extensible Machine Agent written by Charlie Lukens appeared first on Application Performance Monitoring Blog from AppDynamics.