Python agent and Gunicorn WSGI web server

This documentation explains requirements and tips for integrating Gunicorn with the New Relic Python agent. To return to the general installation instructions, go to Install New Relic for Python.

The Python agent supports Gunicorn's default sync worker, and the asynchronous eventlet and gevent workers.

Integrate the New Relic agent

You can use the recommended admin script integration method with Gunicorn. Here's an example of wrapping your startup command using the admin script:

NEW_RELIC_CONFIG_FILE=/PATH/TO/newrelic.ini newrelic-admin run-program gunicorn YOUR_COMMAND_OPTIONS

You can also export the config file location before starting Gunicorn:

NEW_RELIC_CONFIG_FILE=/PATH/TO/newrelic.ini
export NEW_RELIC_CONFIG_FILE

newrelic-admin run-program gunicorn YOUR_COMMAND_OPTIONS

Framework integration

In addition to the main Gunicorn script, the Gunicorn package also provides the gunicorn_django and gunicorn_paster scripts. These provide a simplified script when wishing to host Django or a Paster compatible web applications.

As before, the newrelic-admin command can be used with the gunicorn_django:

NEW_RELIC_CONFIG_FILE=newrelic.ini newrelic-admin run-program gunicorn_django

and gunicorn_paster commands:

NEW_RELIC_CONFIG_FILE=newrelic.ini newrelic-admin run-program gunicorn_paster production.ini

If using Django, it is also possible to list gunicorn in the INSTALLED_APPS setting of Django. When this is done the Django management command script can be used.

NEW_RELIC_CONFIG_FILE=newrelic.ini newrelic-admin run-program python manage.py run_gunicorn

Preloading applications

As part of Gunicorn's process management features, one can enable preloading of your application. When this is enabled the WSGI script file or module will be preloaded into the parent master process. Worker processes will then be forked from this master process.

This can cause problems if the WSGI script or module when loaded creates a background thread which is supposed to run in each worker process, as that background thread will be killed when the worker process are forked.

The Python agent uses a background thread to report data back to our data collector on a regular interval. Under normal circumstances this will only be created upon the first web request being received. As that would normally be in the worker processes, use of preloading should not cause a problem.

If however you have added instrumentation to track calls to certain functions as background tasks and those functions are called on loading the WSGI script file or module, the agent background thread will be started in the master parent process. With the background thread then being subsequently killed when worker processes are forked, no data will be reported for the actual web application.

If using preloading, you should then aim to restrict it to only being used to preload code and not triggering actual code execution to perform tasks. Any such processing when the WSGI script file or module is loaded should be deferred to worker processes by using Gunicorn's post_fork hook.

For similar reasons, one should avoid executing code to perform tasks in Gunicorn's on_starting, on_reload, when_ready, pre_fork and pre_exec hooks.

For more help

Join the discussion about Python in the New Relic Online Technical Community! The Technical Community is a public platform to discuss and troubleshoot your New Relic toolset.

If you need additional help, get support at support.newrelic.com.