Like many other, I was not able to make AppDaemon run with my duckdns when using vkorn images running v2.0.8. So I created another images that you can install from my repository that run version 2.1.10.
With this addon version, you can set the debug level of your choice (as per appdaemon option) and you can also easily change between websockets or SSE.
In addition to the release version from the master branch, there’s also a AppDaemon Dev plugin that is built from the latest dev branch for those who want to try it. This images is built daily by TravisCI.