node selector

A node selector is a key-value label matcher in Kubernetes that ensures a pod is scheduled only on nodes bearing those labels. When you add a nodeSelector field to a pod specification, the scheduler will only place that pod on nodes whose labels match all the selectors you've defined.

For example, if you label a node with disk=ssd, then add nodeSelector: {disk: ssd} to your pod spec, the pod will only run on that SSD-equipped node. This is useful for workloads with specific hardware requirements or topology needs.

Node selectors are simpler than node affinity rules but less flexible—they only support exact label matching. For more complex scheduling logic (like OR conditions or preferred placements), use node affinity instead.