How Kubernetes Handles Load Balancing: Services, Ingress, and Strategies

Kubernetes (K8S) is a modern container orchestration platform that provides automated deployment, scaling, management, and powerful load‑balancing capabilities.

Load balancing in K8S is divided into internal (within the cluster) and external (exposing services outside the cluster).

Internal load balancing routes traffic to multiple Pod instances using the Service abstraction and the kube-proxy component, which watches the API server for Service and Endpoint changes and programs Linux kernel IPVS rules to distribute traffic according to selected algorithms such as round‑robin, weighted round‑robin, least connections, IP hash, or consistent hashing.

External load balancing exposes a Service via a public IP, typically by creating a cloud provider’s load balancer (e.g., AWS Elastic Load Balancer, GCP Cloud Load Balancer) when the Service type is LoadBalancer, or by using Ingress controllers.

K8S supports several load‑balancing strategies:

Round‑Robin distributes requests evenly across Pods.

Weighted Round‑Robin assigns different weights to Pods to direct more traffic to higher‑capacity instances.

Least Connections sends traffic to the Pod with the fewest active connections, suitable for stateful services.

IP Hash routes based on client IP for session affinity.

Consistent Hashing ensures the same request consistently reaches the same Pod, useful for caching or sticky sessions.

Through Services and Ingress, K8S can efficiently distribute traffic and adapt to various application requirements, ensuring stable operation of containerized workloads under high load.