Kubernetes Networking

Accessing containers

While you're inside a container, you cannot access it by curling its container IP like Docker Compose. Since you are inside the container, you should be using the hostname localhost. To see which port to use, enter this command while inside the container: ss -ln.

Ports in Kubernetes

https://medium.com/@deepeshtripathi/all-about-kubernetes-port-types-nodeport-targetport-port-containerport-e9f447330b19

containerPort

Pod object: Informational purposes only (no effect on actual deployment) Service object: Port on which app can be reached out inside the container.

Service object exposes internal pod endpoints as service to outer world

port in Service object

Service will be exposed INTERNALLY to cluster aplications on this port

nodePort

Service will be exposed EXTERNALLY to cluster on this port

If you want to access the pod from the external world: host-ip:nodePort

What happens when we hit host-ip:nodePort? 1. Sends traffic received on nodePort and forwards that to port which is also defined in the Service object. 2. Traffic now gets redirected from port to targetPort which is also defined in the Service object. targetPort used to define port on which container has exposed application.

Note: targetPort and containerPort must be identical most of the time - port that is open in container would be the same port you want to send traffic from service via targetPort

Liveness/Readiness Probe

Performed by the kubelet, so you are within the node - nodeIPs are irrelevant here (check image in Kubernetes networking for clear picture)