Howtoforge published a tutorial about using node affinity in Kubernetes.
Use Node Affinity in Kubernetes
Node affinity is a set of rules. It is used by the scheduler to decide where a pod can be placed in the cluster. The rules are defined using labels on nodes and label selectors specified in pods definition. Node affinity allows a pod to specify an affinity towards a group of nodes it can be scheduled on. We can limit a Pod to only be able to run on a particular Node(s).
Use Node Affinity in Kubernetes
