What Are Kubernetes Services and Why Do You Need Them?

Key Takeaways

That's where a service comes in. Let's now talk about services in Kubernetes. So we have two sets of applications deployed on our cluster. A web server and a radius server. So Kubernetes assigns a unique IP address to each pod in the cluster. The web server in this case has the IP 10.244.0.2 and the pod has the 10.244.0.11. These are the IP addresses assigned to pods in a Kubernetes cluster. So there's an internal network formed and all the pods have internal IP addresses with which they can kind of communicate with each other. So in our example, the web server needs to access the reddish service. So here's the code of our web server and what do you think would be the address that the web server should put here to connect to the radius service? The Reddis pod has an IP address. Now, can the web server address the Reddis service using its IP address? Now, it can technically, but it shouldn't because this IP is for each pod and it is bound to change if the pod were to crash or restart for some reason. So, you don't really want to kind of tie down the IP address into code, of course. So, that's where a service comes in. So, a service enables communication between applications within a Kubernetes cluster. So think of a service as a proxy or a load balancer although it technically is not in a traditional sense and it provides an endpoint for other services to connect to. This case we create a service named radius DB and now the web application can refer to the service with the name radis DB. Now similarly to expose the web service outside to the external users you would create another service for the web server. We will call it the web service. So a service enables connectivity between applications within the cluster as well as to expose applications outside the cluster to end users.