Celery is a powerful, production-ready asynchronous job queue, which allows you to run time-consuming Python functions in the background. A Celery powered application can respond to user requests quickly, while long-running tasks are passed onto the queue. In this article we will demonstrate how to add Celery to a Django application using Redis.
Jenkins is an easy-to-use open-source continuous integration server. In this post we’ll go through steps needed to set up Jenkins to deploy your Django application and run unit tests whenever someone commits code to your project’s repository. If the new code causes any of your tests to fail, Jenkins will send the commiter an email alert.
I recently wrote a book about administering Unix and Linux servers with the aid of the friendly and versatile utility called Webmin. The book covers a wide variety of topics, from setting up and securing a new server to running and monitoring databases (MySQL, Postgres), a web server (Apache) and a mail server (Postfix).
The book is written as a series of 120 step-by-step recipes, which should be easily accessible to both novice and professional system administrators. Check it out to see how Webmin can make your life easier. The book is currently available from Packt Publishing.
Performance testing web applications is a little tricky when we want to test features accessible only to logged in users. Automated test recorders intercept session cookies and hardcode them into test scenarios. When we run these tests later, different session IDs are generated and recorded cookie values don’t grant access anymore. This text demonstrates how to write a scenario for The Grinder to test a Django application. Tests include user login, submitting CSRF-protected forms and AJAX requests.
Nginx makes a great server for your Gunicorn-powered Django applications. In this article I will demonstrate how you can run multiple Django applications on the same Nginx server, hosting sites on two different domains. Each application will be set up in its own Virtualenv and each will be owned by and run as a different user to limit consequences of a potential security breach.
The Grinder load testing framework is a good tool for stress testing your website or application. It can run tests in parallel on multiple machines, allowing you to check how your application would behave under heavy load. This makes it possible to determine your app’s weak points, so you can proceed to optimize them. Unfortunately the TCPProxy component provided with The Grinder sometimes produces flawed testing scripts. I created a simple tool called har2grinder, which produces Grinder test scripts from HAR files. This allows you to record a browsing session using Chrome’s DevTools and then run it in the Grinder.
If you want to run a Django application on WebFaction, you may simply use their automatic application creation scripts. Unfortunately, if you want to place your application in a Virtualenv, the automatic installer will not help you. I’m sure that WebFaction will eventually add an installer to set this up, but for now, you can use the following tutorial. In this text we set up a Django project in a Virtualenv running on WebFaction’s Apache with mod_wsgi.
Slides for a presentation I’m giving today at Warsaw’s Python User Group meetup PyWaw.
Redis is an in-memory key-value store, somewhat similar to Memcached. Because Redis keeps its dataset in memory, storage and retrieval is very fast. It’s a good idea to use this kind of solution for storing ephemeral application data, such as contents of the cache, or temporary information associated with active user sessions. This unburdens your database system from performing unnecessary read and write operations and can considerably speed up your application. Modules for using Redis together with Django are available and quite easy to set up.
Django is an efficient, versatile and dynamically evolving web application development framework. When Django initially gained popularity, the recommended setup for running Django applications was based around Apache with mod_wsgi. The art of running Django advanced and these days the recommended configuration is more efficient and resilient, but also more complex and includes such tools as: Nginx, Gunicorn, virtualenv, supervisord and PostgreSQL.
In this text I will explain how to combine all of these components into a Django server running on Linux.