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

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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.

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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.

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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.