Antonio:
the issue you are facing is at point #1
Puneet Khanna:
but pod is just a logical unit, it doesnt have a port. The port resides on the containers ,isnt it? @Antonio
Puneet Khanna:
can you pls help clarify that
Antonio:
There are 2 networks here. The first one is a network that allows container-to-container communication. On this network the containers can ask (expose) for a port. they communicate like they are in localhost, the network is the same for all. In the case of nginx, it uses the 80 as default, be it can be tuned with its default.conf file. Since, you are running 2 containers in the same pod (aka multi container pod), you need to be sure that all containers are not conflicting to each other.
So, to let you see it better. Imagine for a while the pod as your laptop with one network interface like eth0. On this interface you need to open ports that your applications (containers) need. The network is only one, so your apps need to bind different ports. All these apps communicate with the same ip but different ports.
Then, the 2nd network comes in. The pod-to-pod communication. Imagine your laptop connected to other laptops via router. You need an ip and port on the router to let other to connect to you.
In kubernetes this is done via pod ip and containers ports. To do that, in the yaml file for the containers you need to specify the port like:
ports:
- containerPort: 80
This map the port of the container in the first network with the second network. Hence, you have the pod-to-pod communication.