About networking in Kubernetes

To effectively manage network traffic within a cluster, it is important to have a clear understanding of Services, Ingress, and Ingress Controllers.

What is a Service?

A Service in Kubernetes is an abstraction used to expose an application running on a set of pods. A Service provides access to those pods through a single IP address. Pods can die, be recreated, and change their internal IP addresses, but they can still be accessed through the same service IP address. A Service distributes the incoming traffic to all pods within it.

What is Ingress?

Ingress is a Kubernetes object represented as a set of rules used to route external traffic (ingress) across services inside a cluster. For example, you can map the "/login" route to a specific service in your cluster. So, when a user requests "yourwebsite.com/login", the traffic will be redirected to the service that is responsible for user logins.

To route external traffic to your application, you need three components:

1. Pods with containers that run your application.
2. A Service that routes traffic to pods.
3. Ingress that routes traffic from external networks to service(s).

To fulfill ingress, you need an Ingress Controller.

What is an Ingress Controller?

An Ingress Controller is a Kubernetes tool that reads ingress objects and creates a map of services in a cluster.