What version of Play Framework are you using?
If you use Play 1.x, you need to manually specify the base url of your application using the application.conf variable. So I do to get the base url for my applications. For example:
application.baseUrl=http:
%devcloud.application.baseUrl=http:
%prod.application.baseUrl=http:
Play Framework 2.x ( , - prod, dev, test...), : http://www.playframework.com/documentation/2.2.x/ProductionConfiguration
, . , URL-, .