Baïkal is a lightweight CalDAV + CardDAV server based on PHP, SQLite/MySQL and SabreDAV (http://baikal-server.com).
This git repository will help you to get up and running quickly w/ a Baïkal installation on OpenShift. The backend database is MySQL and the database name is the same as your application name. You can name your application whatever you want.
Create an account at http://openshift.redhat.com/ and install the client tools (run 'rhc setup' after installing it).
Create an application (you can call your application whatever you want) based on this quickstart:
rhc app create baikal php-5 mysql-5 --from-code=https://github.com/fabianofranz/baikal-openshift-quickstart.git
That's it, you can now checkout your application at:
http://baikal-$yournamespace.rhcloud.com
The Baïkal web administration console allows you to manage CalDAV + CardDAV users and other installation properties. The default username and password are admin/admin and the web console is available at:
http://baikal-$yournamespace.rhcloud.com/admin