Interestingly enough, with flannel, docker's advanced networking capabilities become pretty trivial, and communication across hosts is also pretty trivial.
I think all in all, CoreOS has built out a ton of tools to make using Docker easier, and they're all very well defined, and compossible. I'd even say that a lot of docker's features could be completely removed by using some of these tools.
Links? Nah just use ips/dns + etcd for service discovery.
Networking? Need very basic bridged networking, and flannel will handle communication on a single host, or multihost.
Deployment? Use fleet.
Not that all these are 100% perfect like I've made them out to be, but any individual component could be swapped out if you want.
The problem with the CoreOS tools is that they're pretty tightly coupled. We looked into using fleet to manage our deployments. Unfortunately, it relies on a minor feature of etcd and cannot work with Consul, our corporate standard. Flannel? Yep, again, tightly coupled with etcd.
I like some of the ideas behind the CoreOS tools, but until they start playing well with others, they're a non-starter for me. I'm not interested in tools that try to lock me into other, inferior, tools.
I think this is probably more indicative of the issue that Future Docker would like to be a CoreOS-competing platform, and has been edging towards that state. This is CoreOS' natural bounceback from that.
The thing I like about the link model is that they hide your containers from other containers and only expose the connections you want (I think using iptables?)
I'd like a tool that makes this linking easier outside of Docker, but for now this is one of the features I like about it (although holy moly do Docker links have a lot of baggage you have to bring along for the ride, like giving everything names).
From the docs, it looks like that has a dependency on Docker, which kind of defeats the purpose. If I'm stuck with Docker, I'm better off just sticking with links: I'm looking for something that could work with systemd-nspawn, etc.
I think all in all, CoreOS has built out a ton of tools to make using Docker easier, and they're all very well defined, and compossible. I'd even say that a lot of docker's features could be completely removed by using some of these tools.
Links? Nah just use ips/dns + etcd for service discovery.
Networking? Need very basic bridged networking, and flannel will handle communication on a single host, or multihost.
Deployment? Use fleet.
Not that all these are 100% perfect like I've made them out to be, but any individual component could be swapped out if you want.