As I understood CoreOS (and SmartOS and their ilk) the benefit is to run it on bare metal and then spin up VMs or docker images or zones to do your actual computing. What, then, is the benefit of a VM with CoreOS?

I suppose you could run a collection of containers inside a container, but at some point you're going to run out of benefits.

CoreOS seems great, I just thought it was more useful as the OS on your dedicated box, not your VPS.

Surely using less resources in any machine is useful as it leaves more for your actual app to use. Admittedly you might get _more_ benefits from having it on bare metal, but on the other hand the OS using 10% less ram (for example) on a small VM might make more of a noticeable difference to your app.

Personally I prefer having cloud machines to bare metal machines simply for my time being saved in doing things like firewalling them or load balancing. But then my personal time is more precious to me than a few extra £ a month out of my pocket, so that's an active choice I make. CoreOS (& docker especially) seem pretty neat, regardless of where I want to run them as it were.

Perhaps you're right though, I've not used CoreOS in anger yet so I don't know specifically. :-)

There are a lot of benefits to running the same operating system on bare metal and cloud, even if the cloud instances are not as performant as the bare metal.

Move containers around, scale out easily, etc.

I must be missing something, but it seems like CoreOS is just etcd and vanilla docker. I do like the idea of etcd, but is there some sort of API to control docker with it?

To me (docker user and contributor) CoreOS is simply the smallest distro which can run docker. That is already extremely nice when building minimal server images: faster boots, less disk usage and so on.

To me etcd is a completely separate (and also awesome) project. If I use it, it will be as an agent on all my host machines, including Ubuntu and red hat-based ones.

Been meaning to play with CoreOS as a next step on from just using docker. Hadn't yet gotten around to it, this will make giving it a test run so much easier when I get to it. Awesomesauce.