In one of our projects, GEYSER, we were looking into a way of packaging customized code for a pilot test. Generally, we developed µservices which communicate with key Openstack components and we have specifically modified Openstack Horizon code by adding a new dashboard. These µservices as well as Openstack Horizon are quite decoupled from the core Openstack system meaning that communication is done mostly through external API calls rather than a message bus. A number of packaging options were considered: basic packaging python code is relatively straightforward but does not offer the flexibility we require, specifically around rollback. Other solutions include virtual environments or virtual machines, but ultimately, we decided to use Docker containers they are all the rage these days. This blog post describes step-by-step how to containerize Horizon in docker, noting any particular issues we observed in the process. Continue reading