Explain the concept of Affinity in Kubernetes and how it affects pod distribution across nodes.

Affinity in Kubernetes is a mechanism that allows you to set rules for scheduling pods on cluster nodes.

There are two main types of affinity:

• Node Affinity — sets preferences or requirements for nodes where pods can run, for example, based on node labels.
• Pod Affinity/Anti-Affinity — sets rules for pods to be placed near other pods (affinity) or on different nodes (anti-affinity).

This affects pod distribution so that the scheduler considers these rules when selecting a node, ensuring, for example, high availability, load balancing, or resource compliance.

Example of Node Affinity in a manifest:

spec:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: disktype
            operator: In
            values:
            - ssd