When a container runs on a machine, one has to specify the port on which it should run, so other services in the machine can access to this container via port. But in kubernetes, each pod has their own IP address and user can mention incoming port, so other pods can communicate via IP:Port address.
So what is the need for having target port. I feel one can set any port for "target port" field and the other pods will be seamlessly able to communicate with it.
---
apiVersion: v1
kind: Service
metadata:
name: my-service
spec:
ports:
- port: 8080
targetPort: 8070
nodePort: 31222
protocol: TCP
selector:
component: my-service-appport: is the port used by the k8s service
target port: is the port on which the pod is serving the app
nodePort: is the port on which the service is exposed outside the cluster