As niharvey pointed out, we need to tell docpad to listen on a specific address. In version 6.58 of docpad the "host" option was added to the environments section of the docpad.coffee file. So it needs to have the following section:
environments:
development:
# //Always refresh from server
maxAge: false # default
# //Listen to port 9778 on the development environment
port: 9778
production: # //this is the important part for openshift
# //this is the part that open shift needs -
# //but its only available in docapd 6.58+
hostname: process.env.OPENSHIFT_NODEJS_IP
port: process.env.OPENSHIFT_NODEJS_PORT