I think that's an important point, and one which container vendors are not going to labour, as they want as many people as possible on their platform, even before they really need it. A lot of people are trying to use docker or coreos who really don't need to, and as they're not the focus of containerisation efforts, they'll suffer as they find out they're not really tailored to what they want to do, which is just get their small web service running reliably with the minimum of fuss, and be sure they can rebuild it or move it between providers easily.

If you have 1-10 machines which don't change much, use Ansible or similar to get predictable (re)deployments and don't worry about using containers.

If you have > say 10 machines, this sort of stuff becomes more useful, because you are herding cattle, and need the infrastructure necessary to keep that herd going, even if a few die off from time to time - then you can scale to hundreds easily as your business grows, you can manage lots of workers reliably on one VM in containers etc, etc.

For probably 90% of websites out there, with a sane setup that's never even going to become an issue and they could run easily on just a few servers.

you either heal it back or you shoot it. shooting is way faster and docker could help you by that.

Also 1-10 servers could be much, it really depends how much stuff you need.

Also docker adds "some" security. Docker isn't the perfect match, but on our site we run a match between ansible and docker (without coreos) and are very happy.

In our aws cloud we have another system which only uses fleet and coreos, the cluster upgrades itself which is a big plus, but doesn't work that good in our internal infrastructure with proxies, firewalls, etc..

We run 5 machines in aws.

And have like 6 vsphere esxi nodes.