This pattern demonstrates the use of Kubernetes node affinity, node taints, and Pod tolerations to intentionally schedule application Pods on specific worker nodes in an Amazon Elastic Kubernetes Service (Amazon EKS) cluster on the Amazon Web Services (AWS) Cloud.
A taint is a node property that enables nodes to reject a set of pods. A toleration is a Pod property that enables the Kubernetes scheduler to schedule Pods on nodes that have matching taints.
However, tolerations alone can’t prevent a scheduler from placing a Pod on a worker node that doesn’t have any taints. For example, a compute intensive Pod with a toleration can unintentionally get scheduled on a general-purpose untainted node. In that scenario, the node affinity property of a Pod instructs the scheduler to place the Pod on a node that meets the node selection criteria specified in the node affinity.
Taints, tolerations, and node affinity together instruct the scheduler to schedule Pods consistently on the nodes with matching taints and the node labels that match the node affinity node-selection criteria specified on the Pod.
This pattern provides an example Kubernetes deployment manifest file, and the steps to create an EKS cluster, deploy an application, and validate Pod placement.
