Today I decide to signup for a free trial of the newrelic monitoring agent and I wanted to write on how to setup the agent on a Pylons app.
EDIT: Commenter Graham Dumpleton has advised against this setup in the comments. There’s the potential risk of the agent initializing twice and additional modules not working correctly. So please don’t use this setup on a production app.
Open the middleware.py file located on PRJNAME/config and add the following. Make sure to set the correct path where your newrelic.ini file is located

#import the agent
import newrelic.agent
#create a middleware class to initialize the agent
class NewRelicAgent(object):
    def __init__(self, app):
        self.app = app
        newrelic.agent.initialize('/path/to/the/file/newrelic.ini')
    @newrelic.agent.wsgi_application()
    def __call__(self, environ, start_response):
        return self.app(environ, start_response)

Now it’s time to add our custom middleware inside the make_app def

# CUSTOM MIDDLEWARE HERE (filtered by error handling middlewares)
app = NewRelicAgent(app)

And that’s it. Now it’s time to collect some stats :).