Docker vs. Kubernetes: What’s the Difference?

If you start your journey with containers and applications, you have surely heard of Docker and Kubernetes technologies. These solutions are very popular among application developers nowadays. So you can ask yourself what is the difference between Docker vs. Kubernetes: What's the Difference?

Let's figure out the basics behind them.

The easiest way to explain the difference between these solutions is that Docker is responsible for creating and running containers, while Kubernetes is for managing these containers. Let's see how these platforms operate.

What Is Docker?

Docker is a containerization platform that enables software engineers to develop reusable container images. An image contains all that is required to launch applications. This technology eliminates typical issues like working applications in one environment and failing in others.

Using Docker, you can:

• Create container images for your applications
• Run containers in any environment
• Create development and test environments
• Make application deployment simpler
• Combine several containers using Docker Compose

So let's say you build an ASP.NET Core application. Normally, you should install and configure the application's requirements (.NET environment) in every place where you want to test it. You'll do this once when creating a Docker image of your application. Later, you can run this Docker image as a container on your computer, test server, and even in the cloud environment. And the most significant advantage here is the predictability.

What Is Kubernetes?

Kubernetes (usually abbreviated K8S) is an open-source platform that enables the automated deployment, scaling, and management of containerized applications. If the first step was to simplify the process of running applications in containers, now the question is how to simplify their management. And this is the main idea of Kubernetes.

Kubernetes manages containers, grouping them into units called Pods. They are launched in the Kubernetes clusters of machines named nodes.

There are a number of features that Kubernetes provides:

• Autoscaling: scales the number of application replicas according to the load if there are corresponding rules
• Self-healing: can restart failed containers or replace failed pods
• Load balancing: distributes the traffic between replicas of the application
• Rolling updates: updates the application version in a gradual manner
• Service discovery: makes possible applications communication using names rather than IP addresses

For example, usually there are several replicas of your application running to deal with load. But you have a campaign that raises the traffic several times and requires extra replicas of your application. So Kubernetes, if there are the correct settings, will automatically increase and then decrease the number of replicas. It will make sure that the application can respond correctly to the requests while wasting fewer infrastructure resources.

Docker vs. Kubernetes: Differences

So as you can see, both solutions can be applied to containers, but their purposes are somewhat different.

When working with containerized applications, Docker and Kubernetes have distinct roles to play. While Docker is concerned about container creation, management, and execution, it makes for the right tool in terms of local software development and testing, and for smaller-scale applications. It is not hard to learn how to use Docker, and it provides for easy development of consistent working environments.

In contrast, Kubernetes is intended for orchestration and management of container operations on multiple hosts at once and is particularly relevant for large-scale distributed applications. While Docker offers Docker Compose for working with more than one container, Kubernetes allows for automatic application scaling, load balancing, auto-healing, and rolling deployments.

How Docker and Kubernetes Work Together

As you can see, these two technologies are not competitors. In some cases, both Docker and Kubernetes are required, and they work in concert. For example, think about an online shopping application. Your application consists of the frontend, API backend, and a database.

Here you can use Docker and Kubernetes:

• Application development: You develop frontend and backend services of your application
• Creating Docker Images: You package each application part into a container
• Testing the application locally: You can start the application using Docker Compose
• Publishing your images to a container registry
• Launching the application in Kubernetes
• Managing production workload: Using Kubernetes

It should be noted that Kubernetes doesn't use Docker Engine anymore by default. The main runtimes here are containerd and CRI-O. However, Docker images work well with Kubernetes.

Which One Should Be Learned First?

If you are a beginner and you want to start using containerization technology, you will find it useful to start with Docker first. You should get the basic knowledge of containers, images, Dockerfile, networking, volumes, etc. Only after getting this information can you move on and study Kubernetes. So learn Pods, Deployments, Services, and other things related to Kubernetes that make it possible to handle applications. Also note that you may not need Kubernetes for each of your projects.

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