k8s for Beginners — port vs targetPort vs NodePort

When I first started working with Kubernetes, configuring Services was one of the more challenging aspects for me.

I remember feeling overwhelmed by the different port-related terms: port, targetPort, and NodePort.

Each seemed to have its own role and impact, and it took me some time to grasp how they worked together.

To simplify things, I decided to break down these concepts into more manageable pieces and see how they interacted in a typical setup.

In Kubernetes, when you set up a Service to expose your applications, you’ll work with three key types of ports: port, targetPort, and NodePort. Here’s a simple explanation of each:

Port

• Definition: This is the port on which the Service is exposed within the Kubernetes cluster.
• Usage: Other components within the cluster use this port to communicate with the Service. It acts as a stable entry point for Pods.
• Example: If the Service has a port set to 80, it means the Service can be accessed at port 80 within the cluster.

TargetPort

• Definition: This is the port on the Pod where the application is actually listening.
• Usage: The Service forwards traffic to this port on the Pod. It allows the Service to direct traffic to the correct Pod port, even if the port numbers differ.
• Example: If the…