Kubernetes is an open-source container orchestration system that manages containerized workloads and services. One of the key features of Kubernetes is its ability to automatically load balance traffic to a set of backend servers. In this article, we will walk through the process of creating a Round Robin load balancer in Kubernetes.
Kubernetes uses the Service object to expose backend services to the external network. By default, Kubernetes uses a random selection algorithm to distribute traffic across the backend servers. However, in some cases, you may want to use a different load balancing algorithm, such as Round Robin, to evenly distribute traffic across the backend servers.
Table of Contents
- Prerequisites
- Create a Deployment
- Create a Service with Round Robin Load Balancer
- Verify Round Robin Load Balancer
Prerequisites
Before we begin, ensure that you have a Kubernetes cluster set up and running, and kubectl command-line tool installed on your local machine.
Create a Deployment
The first step is to create a deployment with a backend server. We will use the Nginx web server as an example. Run the following command to create a deployment with a single replica:
kubectl create deployment nginx --image=nginx
You can verify that the deployment has been created by running the following command:
kubectl get deployments
Create a Service with Round Robin Load Balancer
Next, we will create a service that exposes the backend server to the external network using the Round Robin load balancing algorithm. Run the following command to create a service with the Round Robin load balancer:
kubectl expose deployment nginx --port=80 --type=LoadBalancer --name=nginx-lb --external-ip=<YOUR-EXTERNAL-IP> --load-balancer-ip=<YOUR-LOAD-BALANCER-IP> --load-balancer-algorithm=round-robin
In the above command, replace <YOUR-EXTERNAL-IP> and <YOUR-LOAD-BALANCER-IP> with your external IP address and load balancer IP address respectively.
You can verify that the service has been created by running the following command:
kubectl get services
Verify Round Robin Load Balancer
Finally, we will verify that the Round Robin load balancer is working as expected. Run the following command to get the IP address of the service:
kubectl get services nginx-lb
Use the IP address to access the backend server via a web browser or curl command. You should see the response from the backend server. Repeat the same command multiple times, and you should see the responses alternating between the backend servers.
Congratulations! You have successfully created a Round Robin load balancer in Kubernetes.
More Examples
You can also use the Round Robin load balancing algorithm with other types of services, such as StatefulSets and DaemonSets. You can specify the load balancer algorithm using the --load-balancer-algorithm flag when creating the service.
You can also customize the load balancing algorithm by creating a custom service using the Kubernetes API. For example, you can create a service with a specific session affinity algorithm, such as IP hash or cookie-based affinity.
In this article, we have shown how to create a Round Robin load balancer in Kubernetes. Load balancing is an important feature of Kubernetes that helps to distribute traffic across backend servers and improve application performance and reliability. By using different load balancing algorithms, such as Round Robin, you can customize the behavior of the load balancer to suit your specific needs.
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That's it for this post. Keep practicing and have fun. Leave your comments if any.