> The minimal Ubuntu 12.02 image is 627MB. Add your own application layer, and your container will most likely weight more than 1GB. I've read that using Debia

> The minimal Ubuntu 12.02 image is 627MB. Add your own application layer, and your container will most likely weight more than 1GB. I've read that using Debian (or if possible Busybox) helps in this area. See http://container-solutions.com/2014/11/6-dockerfile-tips-official-images/ http://container-solutions.com/2014/11/6-dockerfile-tips-off... and http://jonathan.bergknoff.com/journal/building-good-docker-images http://jonathan.bergknoff.com/journal/building-good-docker-i... for tips. > Every time your application is updated, check the Gemfile md5 and see if it’s different from the latest build Wouldn't you need to check Gemfile.lock? With optimistic/pessimistic version constraints you could get newer gems without updating the Gemfile.