Kubernetes networking is a complex topic, made even more so by the fact that there are a number of different ways to configure it. In this article, we'll focus on the communication between pods and services.
Pods are the basic units of deployment in Kubernetes and can be thought of as containers on steroids. They can contain multiple containers, have their own IP address and can be used to isolate applications from each other.
Services are used to expose applications running in pods to the outside world. They can be exposed using a number of different methods, including ClusterIP, NodePort and LoadBalancer.
When a service is created, Kubernetes creates a virtual IP (VIP) address that is used to route traffic to the pods that are part of that service.
Communication between pods is handled by the Kubernetes networking layer. By default, each pod is assigned a unique IP address within the cluster and can communicate with other pods using this address.
Pods can also communicate with each other using hostnames. By default, each pod is assigned a hostname that is based on its IP address. For example, if a pod has an IP address of 10.0.0.1, its hostname would be 1-10-0-0-1.pods.cluster.local.
Communication between services is handled by the Kubernetes networking layer. By default, each service is assigned a unique IP address within the cluster and can communicate with other services using this address.
Services can also communicate with each other using hostnames. By default, each service is assigned a hostname that is based on its IP address. For example, if a service has an IP address of 10.0.0.1, its hostname would be 1-10-0-0-1.services.cluster.local.
Pods can communicate with services using either the service's IP address or hostname. By default, pods are assigned a hostname that is based on the service's IP address. For example, if a pod has an IP address of 10.0.0.1 and a service has an IP address of 10.0.0.2, the pod would be able to communicate with the service using the hostname 2-10-0-0-2.services.cluster.local.
Pods can also communicate with services using the service's ClusterIP address. By default, the ClusterIP address is assigned to the pod's default network interface. For example, if a pod has an IP address of 10.0.0.1 and a service has a ClusterIP address of 10.0.0.2, the pod would be able to communicate with the service using the ClusterIP address.
Kubernetes networking is a complex topic, but the communication between pods and services is a key part of it. In this article, we've covered the basics of how pods and services communicate with each other.