Session affinity

Session affinity

•  Session affinity, also known as sticky sessions, is a technique used in load balancing to route requests from a client to the same server that previously handled its requests. This can be particularly useful for applications that store session data on a specific server and need to maintain continuity between subsequent requests.
• Basically, Session affinity in Kubernetes (often referred to as "affinity" for short) is a feature that allows you to control how the scheduling of network requests is managed for a specific set of pods in a deployment or service. When you set session affinity, Kubernetes tries to ensure that requests from the same client are consistently routed to the same pod instance, based on some defined criteria.
• In the context of Kubernetes and pods, you can implement session affinity using a load balancer or an ingress controller. Let's assume you have a Kubernetes Service and you want to configure session affinity for it. Here's how you can do it:

aadi.yaml

apiVersion: v1

kind: Service

metadata:

  name: my-app-service

spec:

  selector:

    app: my-app

  ports:

    - port: 80

      targetPort: 8080

  sessionAffinity: ClientIP

In the example above, 

 sessionAffinity: ClientIP # This line enables session affinity,we have service kind.

the `sessionAffinity` field is set to `ClientIP`, which means that requests from the same client IP will be directed to the same pod. This is a basic form of session affinity that's determined by the client's IP address.

after that 

kubectl apply -f aadi.yaml

Note- Session affinity can have implications on load balancing and scaling. While it ensures continuity for a specific user session, it might not distribute traffic as evenly as non-affinity load balancing techniques, potentially leading to uneven utilization of resources.