Getting Started with OpenShift

Chapter 4. Adding Application Components

OpenShift cartridges provide the components for building your application infrastructure. Our example Python app currently utilizes a single cartridge, Python 2.7. In this chapter, we will demonstrate how to add cartridges that provide additional capabilities, such as data storage, task scheduling, and monitoring. We will also explain how to find and use third-party cartridges created by the open-source community or OpenShift partner organizations.

Tip

This chapter shows how to add cartridges to an OpenShift application after it has been created. However, you can also select multiple cartridges when you create your app. To do this, add the extra cartridge names or URLs after the primary cartridge name. For example, to create a PHP 5.4 application with Cron and a MySQL 5.5 database, you could use the following command:

rhc app create appname php-5.4 mysql-5.5 cron-1.4

Database-Related Cartridges

The cartridges most commonly added to OpenShift applications after creation are database cartridges, such as PostgreSQL, MySQL, and MongoDB. If the application is not scalable, the database cartridge will be installed on the same gear as the primary application cartridge. If the application is scalable, the database cartridge will be added on its own gear. This enables the gear hosting the application cartridge to be replicated, without affecting the database. It also prevents the application server and the database from sharing the memory and disk space ...