There are already a couple pretty good responses, but I would add that all of the technologies you mentioned (along with others in this space) are still evolvin

There are already a couple pretty good responses, but I would add that all of the technologies you mentioned (along with others in this space) are still evolving and maturing. Docker popularized containers, and now we're seeing the supporting technologies that will help fulfill some of the promises of container-based deployment. Big companies have had this technology internally for years, and now it's starting to get productized. I'm referring to things like schedulers, networking, monitoring, etcd/consul, and more. I personally don't think all of the pieces are there yet to make it as seamless and easy as it could be, but it's coming.