I have been working with Docker for quite some time now and already have a production environment that started small but now has grown to more than 50 Linux nodes, each of those nodes running one Docker container.
I have been orchestrating everything using custom python scripts and so far it has worked great, but since we will probably continue the expansion, I'm thinking that at some point I will be needing a reliable, flexible orchestration tool, so might as well start planning eveything now.
I started reading about docker orchestration options, and so far I've narrowed it down to two options: Kubernetes or docker-swarm.
Looking at Kubernetes, it seems like the right choice (as a robust, flexible orchestration system), but I'm not sure if it's suitable for my environment. From what I've been reading, it can't handle already existing docker containers, it can only be used to create a new cluster from the ground up. In our case, we're using dedicated servers with special hardware requirements, so there's no way that we could have another parallel, alternate cluster where we could start fresh with Kubernetes.
On the other hand, docker-swarm looks to be more suitable for orchestrating existing docker containers, but seems to have reliability and scaling issues.
Can someone with extensive Kubernetes/docker-swarm experience give me a bit of advice on how I should approach the migration to an orchestrated docker cluster, without the need to create one from scratch (since it's impossible in my case)?