Right now, there is no way of customizing those values for the hourly docker-gc cron job. The defaults are not good enough for us since our docker images are quite big and the disk gets fill up very quick. We also run a RAM drive for the runners, which requires different clean up params from the builders.

I imagine and approach could be to add those variables to the cloud formation template parameters, and generate the cron job on provision time, rather than image building time. Another option is to generate a file on provision time that the cron job would source when it runs. Thoughts?