As of Deis 0.8.0 it only runs on CoreOS, and I believe most other DIY PaaS systems are moving the same way.
IMO Docker + etcd is a far more sane configuration than endless Ruby Chef scripts, or worse, Amazon OpsWorks.
ie. how do i update the load balancer as i add capacity to my web app, how do i setup a new db instance and open up the firewall rules to an app on a different host. etc.
docker, and etcd are both nice pieces, but they don't make a complete picture. nor does fleet imo.
If you want to do orchestration of both the infra and the app, you need things like opsworks.
It's still pretty early, so much of the tooling will need more improvement before container-based infrastructure gets more mainstream (e.g. enterprise, smaller teams) uptake.
Configuration management (puppet, chef, salt, ansible) is a completely different beats than service discovery, health management, etc.
While I enjoy working with Chef, have had some pretty reasonable times with Puppet, these full-run tools do have issues sometimes where you introduce a narrow bug in your user management or some other code, and all of a sudden you can't update some random conf file that happens after it. I've also seen tools like capistrano and fabric bastardized to allow this sort of precise updating, but lose the cohesion of typical config-managed systems.
With something like etcd, certain problems are solved by not relying on static configuration. That is the paradigm shift, and it is similar to Hadoop. When I've built Hadoop systems with puppet, we simply wrote out the same configs and files on every machine, then chose which services to start, and via zookeeper things like primary / secondary failover take care of themselves.
For instance, there is a tutorial on using vulcand as your http load balancer, which is driven by configuration in etcd. A tutorial on the CoreOS site shows you how to use this to cleanly deploy a new version of an app as new versions of a container, and to rotate them into the LB and to rotate the old ones out.
You can also connect a script that controls firewall rules based on etcd, its' changes would be reflected almost immediately, rather than the splayed 30-60min period of seemingly-randomly-applying-changes you typically see with config runs of tools like chef and puppet.
I've been trying to figure out where tools like chef, fabric, and docker/coreos/etcd/fleet will play together, what the boundaries will be, etc.. In situations where I'm using Docker and CoreOS, I don't expect to use chef, but I'm not sure it will be used for things like database servers, which we typically dedicate and tune hosts for.
It would be nice to see something like chef running on CoreOS for, say, user management so that people who want to talk to, say, fleet aren't required to all ssh as 'core'.
Another is that your configuration is wide open to every node in the cluster (e.g. your Web app's etcd client can read the key that stores the master database user password). Hope you never get hacked!
For what use case? Doesn't using Docker for everything take you into 'golden master image' dead-ends, as outlined by the Opscode guys in comments to a Docker blog post last year [1].
What Lamont and Joshua had to say in that thread resonated, but I haven't really looked into DevOps approaches with Docker.
I'm also not sure what you mean by 'endless Ruby Chef scripts'?
[1] http://blog.relateiq.com/why-docker-why-not-chef/#comment-43...
So yes, powering 20 thin clients running different apps from a single server is a perfect use case.
What I want is to make groups of containers that can talk only to each other(only to containers within one group). Does CoreOS provide something like that? Maybe kubernetes? What are possible options?
Deis is the best thing I've seen come out of Docker's DevOps gold rush.
I have to agree - Deis fills a lot of holes, although it still has some way to go.