Just to add to this, don’t add this option to the build phase (at least in Dokku 0.3.22) it will fail with rm: cannot remove ‘/app/public/images’: Device or resource busy error while pushing or rebuilding, and won’t launch the app.

Handy functions to check that it’s correctly set up are:

• sudo docker ps
• sudo docker inspect (app_image_NAME)

The bottom of the json object will have the following values:

"Volumes": {
    "/app/public/images/projects/images": "/home/dokku/uploads/katz"
},
"VolumesRW": {
    "/app/public/images/projects/images": true
}