使用确定性主机名在每个节点上运行一个Pod

Question

I have what I believe is a simple goal, but I can't figure out how to get Kubernetes to play ball.

For my particular application, I am trying to deploy a number of replicas of a docker image that is a worker for another service. This system uses the hostname of the worker to distinguish between workers that are running at the same time.

I would like to be able to deploy a cluster where every node runs a worker for this service.

The problem is that the master also keeps track of every worker that ever worked for it, and displays these in a status dashboard. The intent is that you spin up a fixed number of workers by hand and leave it that way. I would like to be able to resize my cluster and have the number of workers change accordingly.

This seems like a perfect application for DaemonSet, except that then the hostnames are randomly generated and the master ends up tracking many orphaned hostnames.

An alternative might be StatefulSet, which gives us deterministic hostnames, but I can't find a way to force it to scale to one pod per node.

The system I am running is open source and I am looking into changing how it identifies workers to avoid this mess, but I was wondering if there was any sensible way to dynamically scale a StatefulSet to the number of nodes in the cluster. Or any way to achieve similar functionality.

Answer 1

The one way is to use nodeSelector , but I totally agree with @Markus: the more correct and advanced way is to use anti-affinity . This is really powerful and at the same time simple solution to prevent scheduling pods with the same labels to 1 node.