Hardware Requirements for Docker Swarm and Kubernetes

Question

We plan to create a small docker cluster for our applications. We examined the use of 2 master vms for ha, 1 consul (if we chose Swarm) and 5-10 hosts for containers. We have not yet decided what to use - Docker Swarm or Kubernetes.

So, the question is what “hardware” requirements (central processors, operating operators), both Swarm and Kubernetes, can meet to organize this small cluster.

Answer 1

Just to clarify a bit what Robert wrote about Kubernet. If you want to have up to 5 machines to run your applications, one single-core virtual machine (n1-standard-1 on GCE) is enough. As Robert said, you can use a 10-node cluster with a 2-core virtual machine. For official recommendations, please take a look at: http://kubernetes.io/docs/admin/cluster-large/

However, note that using the resources of our core components is more related to the number of containers that you want to run in your cluster. If you want to say their one-bit number, n1-standard-1 GCE should be enough for a 10-node cluster. But it is definitely safer to use n1-standard-2 in the case of clusters <= 10 node.

As for HA, I agree with Robert that having 3 core virtual machines is better than 2. Etcd (which is our backup storage) requires that more than half of all registered replicas work correctly, so in case of 2 instances, they should all be raised (which is usually not your goal). If you have 3 instances, one of them may not be available.

Let me know if you have more questions about Kubernet.

Answer 2

For Kubernetes, a single dual-core virtual machine (for example, n1-standard-2 on GCE) can handle 5 nodes and, possibly, 10. If you want to run the main HA configuration, you most likely want to create 3 quorum nodes for instances etcd, and you may need to provide slightly larger instances (e.g. n1-standard-4) to account for clustering overhead, etc.