Many of the customizations necessary to modify a customer’s Open edX site can be done in the server-vars.yml file which is read by the /edx/bin/update script on the server. Here is a sampling of the variables which can be overridden in this file:

http://www.dangtrinh.com/2014/05/edx-platform-server-varsyaml-variables.html

More specific to our setup:

https://github.com/appsembler/configuration/blob/appsembler/feature/multiserverDeploy/playbooks/appsemblerPlaybooks/base-server-vars.yml