We all talked about this earlier, but I'll try to summarize in bug form. Please fill in any holes. If you look in apps/jetpack/xpi_utils.py flightdeck is writing a shell script to disk called cfx.sh and then popen()ing it to build a the jetpack bundle. It's built this way because we need to setup environment variables to support multiple versions of the add-on SDK. We want to change this to not writing a shell script to disk. We should be setting up environment variables for the popen() process and calling the build command directly from there. I'm sure there will be questions, so feel free to ask and we'll get it sorted but this is the high level view. Note the bug this depends on - this should happen in an offline celery process. This is a backend bug. I'll file a separate one for the front end and make it dependent.