Debugging docker resources

I have created a basic custom resource. Its actually public

check is a simple python script

import sys
print('TEST', file=sys.stderr)
print('[{ "Ref": 1 }]')

If I run this in docker and attach it I can run the check script.

When I use this in a pipeline e.g.

- name: switch_logs
  type: docker-image
    repository: captainstuart/remote-command:0.4
    command: ls
    user: concourse
    key: put key here

The pipeline hangs on no new versions available

when I do a fly intercept of the resource container it is not my container
/opt/resources has some other files

anyone know what is happening?
how is my container being called and how can I debug it ?