Currently I have to pipe the boxgrinder-build output into a file and read the last line (when -p ami) for the Amazon instance id and use a perl script to try to find the path to the image file (os plugin) etc. Not really robust.
I propose one of two interfaces:
1. Have each plugin (optionally) output the details of its deliverables to a machine-readable file (e.g. json)
2. Provide a call-back mechanism on completeion of a plugin with the deliverables information on the command line.
Either one enabled / disabled by config settings and/or BG-builder command line switches
Would really help automate the whole process: build image; possibly extract info from the post process; launch instance; test instance; move image from test to production; etc.