Hey, Dokku seems to let the default port 5000 map even with the "EXPOSE" command in the Dockerfile.
It's happen only with the following steps :

• dokku apps:create my-app
• dokku domains:add my-app sub.domain.com

Then, from the host, git push dokku master, the port inside the Dockerfile is detected but the "DOKKU_PROXY_PORT_MAP" is not updated. If you take a look at the nginx.conf you'll see that.

A workaround for this issue is to run dokku proxy:ports-clear my-app.

Dokku version : 0.6.4

See you !