We've been using Kubernetes to deploy Docker containers on Google Container Engine, and while there have been a few issues due to Docker/Kubernetes (namely, getting the containers to expose localhost to each other, and to expose themselves to the world), the issues that we've had so far have been issues that we would have been bit by eventually. Namely, if we hadn't been forced to deal with the issues now, we would have been screwed later. There have been some weird bugs due to the internal environment that containers use (we had extremely slow DNS lookups that caused our request times to shoot up to 9s each). These issues have been transient though, so it's not clear that it's Dockers fault, or if we're making mistakes in our code.
Docker has made our deployment much easier. You just build & push your container, and you instantly have a versioned deployable instance of your code. Kubernetes makes it extremely easy to rollout or rollback containers, so I have nothing but good things to say about containers.
> Google offers containers as a service, but more importantly, as confirmed by internal sources, their offering is 100% NOT Dockerized.
> Google merely exposes a Docker interface, all the containers are run on internal google containerization technologies, that cannot possibly suffer from all the Docker implementation flaws.
A quick skim would suggests that sits on about 8TB of Ram and 1000vCPUs spread over 100 machines. It's not the biggest stack in the world, but it's doing a good job as our little internal PaaS.
We have some non-aws versions too, but I don't have metrics on those right now.
We went through the gammut of swarm etc. and were never able to get any of them to work in a meaningful way.
Though the tone of this article is very negative, the conclusion is interesting to me as someone that's considered Docker but hasn't done much with it beyond experimenting locally.
I'm assuming if there's any forum that has users that can speak to their use of Docker in production, this would be the place.