If you’re new to the world of containers there are two words you would have certainly come across, but might not yet understand the difference between: Kubernetes and Docker. Although Kubernetes and Docker are somewhat different from each other, they also share some similarities. A container is a standard unit of software that packages the code along with the libraries and dependencies so that the application can run quickly, seamlessly and reliably from one environment to another. The process that helps a container in doing that is known as containerization. Kubernetes is a container orchestration platform, for containerization platforms like Docker. In this article, you will see how Kubernetes and Docker compare with each other and their advantages.

What is Docker?

Docker is an open-source containerization platform that helps with the building, deploying, and managing of containers. With Docker, developers can package and run applications alongside the dependencies required to run them into loosely isolated environments called containers. Docker helps in the quicker delivery of your applications by isolating them from the infrastructure. Docker’s methodology of shipping, testing and deploying code quickly will help in the significant reduction of delay between writing codes and running it in production.

Docker Engine is the runtime that allows a developer to build and run Docker containers. You can create such a container by defining it in a Dockerfile. A Dockerfile is a file in which you define everything that you need to run the image, including the OS network specifications and file locations.

Docker also comes with tools such as Docker Compose and Docker Swarm. Docker Compose is a tool you can use to define and run multi-container Docker applications. Docker Swarm is a container orchestration tool that allows a user to manage different containers deployed across multiple host machines.

Docker components

Source: Official Docker documentation

Benefits of using Docker

Let's take a look at some of the benefits of using Docker:

  • Consistent and isolated environment - With the help of Docker containers, developers can create isolated, predictable environments. In addition, the scaling of Docker containers leads to consistency regardless of the deployment of the application, which results in massive productivity. This includes less time for debugging and gives you sufficient time to launch new and improved features and functionality for users. Docker containers maintain all configurations and dependencies internally and hence, you can maintain the same container from deployment to production leading to a consistent environment. With scaling up, you can consistently add more resources when the demand of your application is high and subsequently, you can scale down during the quieter periods saving a lot of money and resources.
  • Cost-effective - Docker helps reduce the deployment time of images to seconds, which can be a big productivity win. All Docker containers are based on an image. Processes like provisioning which includes allocating of servers and resources and setting up of infrastructure traditionally take a lot of time, but when you put each process in a container, you can share the processes with new apps. Hence, the deployment process is accelerated.
  • Portability - Portability is another benefit of using Docker. Suppose you deploy a tested containerized application to any system where Docker is running, then you can be sure that the application will run without any complications.
  • Scalability - You can create containers according to the needs of your application with the help of Docker. The lightweight and portable nature of Docker allows you to scale up or tear down applications according to the demands and needs of your business. With this, you can easily manage your workloads. There is also a wide range of container management options while using multiple containers.

What is Kubernetes?

Kubernetes, also known as K8s, is an open-source platform that helps in container orchestration. It is portable, extensible, and helps manage containerized workloads and services. It also facilitates declarative configuration and automation. This means that the user can specify the amount of desired instances or resources required for his application and Kubernetes will check the current state of the application and will automatically upgrade or delete the resources to get it to the desired state. Again Kubernetes has a rapidly growing ecosystem.

The Kubernetes architecture comprises three main components: the control plane, the nodes, and the pods. The control plane is the orchestrator. Multiple components in the control plane facilitate an orchestration. Nodes make up the compute power for a Kubernetes cluster, whereas one or more containers make up a pod. Pods run on nodes, and the lifecycle of pods is managed by the control plane.

Kubernetes components

Source: Official Kubernetes documentation

Benefits of Kubernetes

Let's take a look at the several benefits that you can get from using Kubernetes.

  • Scalability - With Kubernetes, you can scale a cluster based on the amount of incoming traffic. Kubernetes has HPA (Horizontal Pod Autoscaler) built-in, determining the required number of replicas for a service. In other words, Elasticity is a core feature of Kubernetes clusters.
  • Availability - Kubernetes is highly available, helping protect your application from any single point of failure. With Kubernetes, you can create multiple control plane nodes, which means that if any one of the masters fails, the other ones will keep the cluster up and running.
  • Reliability and Stability - One of the main benefits that Kubernetes possess is the reliability and stability it brings to a container-based distributed application using dynamic scheduling of containers. This is fairly important because distributed applications are such applications that can run on more than one computer and communicate with each other through a network. A container scheduler helps in starting a container on an appropriate host along with connecting them together. So, through dynamic container scheduling, Kubernetes ensures the stability of a containerized distributed application.
  • Flexible - Kubernetes is highly flexible, meaning it can work virtually with any container runtime. A container runtime is a software component that helps in running a container on a host operating system. In addition, it can work with almost any type of underlying infrastructure, be it a public cloud, private cloud, or on-premises server.
  • Multiple cloud capability - Kubernetes has multiple cloud capabilities. Because of its portability, it can host workloads on a single cloud and workloads spread across multiple clouds. In addition, it can scale its environment from one cloud to another.
  • Open Source - Kubernetes is open-source and falls under the CNCF umbrella. The entire codebase of Kubernetes is available in Github. Cloud Native Computing Foundation or CNCF serves as the vendor-neutral home for many fastest-growing open-source projects and Kubernetes is certainly one of them. Also, it makes the project community-driven, which helps in the consistent fixing of bugs and releases through external contributions.

What are the differences between Kubernetes and Docker?

Docker is a set of tools that allow us to build and manage container images. These containers can be managed (orchestrated) by a variety of tools, including Kubernetes and Docker Swarm. Let's look at some of the differences between Kubernetes and Docker Swarm.

  • Docker Swarm has a similar container orchestration technology to Kubernetes. However, while Kubernetes lets you run any containers on physical or virtual machines clusters, Docker Swarm has tight integration with the Docker ecosystem which allows running of Docker containers across a cluster of virtual machines. A cluster is a group of nodes, servers or computers that acts like a single system and works together to maintain high availability, meaning if one node goes down, the other ones will keep on working.
  • One significant difference is that you can run Docker Swarm on a single node if you are only serving containers from a single host in production, while Kubernetes in production runs across a cluster.
  • Kubernetes has a complex installation for manual installations, whereas Docker Swarm has a more straightforward installation.
  • One stark difference between Kubernetes and Docker Swarm is that you can use the latter without any container runtime because of its integration with the Docker ecosystem, but Kubernetes needs a container runtime or a component to run a container on the operating system of the host, like Docker Engine for orchestration. Up until now you could use the Docker engine as the container runtime in Kubernetes, but that's being removed from version 1.24.
  • Kubernetes supports auto-scaling, while in Docker Swarm, you have to stick with manual scaling.
  • Kubernetes has built-in monitoring. This helps you manage your Kubernetes cluster by tracking uptime, monitoring utilization of cluster resources, and interacting between cluster components. On the other hand, Docker Swarm doesn't have built-in monitoring, needing third-party tools for cluster monitoring.
  • Docker Swarm has an automated load balancer that helps in the balancing of requests across any containers or hosts of the clusters. But, in Kubernetes, you have to set up a load balancer manually.
  • Kubernetes needs a separate CLI (Command Line Interface) tool such as Kubectl to operate, whereas Docker Swarm integrates with the Docker CLI.

Can you use Docker without Kubernetes?

When producing and managing container images and putting the containers into operations at a runtime level, the answer is yes. For example, with Docker, you can build container images and organise them in a registry. You can run containers and communicate with them, and also, you can put the containers together in a multi-container application using Docker Compose. So, you can see that Docker doesn't need Kubernetes because it can do most things independently. But Kubernetes can deploy the Docker containers automatically across IT environments to ensure high availability. Also, alongside running containers, it can provide self-healing with automatic rollouts and rollbacks.

Can you use Kubernetes without Docker?

You can't create or manage container images with the help of Kubernetes. Kubernetes is a container orchestrator, and because of that, it needs a container runtime to orchestrate. Docker possesses a container runtime known as Docker Engine. Also, it is a common practice to use Kubernetes alongside Docker. But, that doesn't mean Kubernetes is entirely dependent on Docker. You can use Kubernetes with other container runtimes such as runc, CRI-O, Containerd, and others. So, it is evident that you can use Kubernetes without Docker, but you would need container images of some type to orchestrate.

What are the similarities between Kubernetes and Docker?

Whilst Kubernetes and Docker are very much two different systems, Kubernetes do share some similarities with Docker Swarm, which is the container orchestration tool for Docker.

  • Both Kubernetes and Docker Swarm are highly scalable.
  • Kubernetes and Docker Swarm both have high availability, which means they can increase the robustness of your application infrastructure by making the application highly available.
  • Both Kubernetes and Docker Swarm are portable, meaning both can work with any infrastructure.
  • Kubernetes and Docker Swarm support the easy maintenance of applications by breaking them down into their constituent parts.

Is Kubernetes better when used alongside Docker?

Creating containers in Docker is pretty much the industry standard. Managing them in Kubernetes is becoming the industry standard. The design of Kubernetes means it works well with Docker and much of the Kubernetes documentation is written keeping Docker in mind. Kubernetes has Docker-centric tools like Kompose, which converts Docker Compose commands and settings so that Kubernetes can use it.

Docker will help in the packaging and distributing of containerized applications, while Kubernetes will allow the orchestrating and managing of your container resources from a single control plane. Using Kubernetes will help you improve the scalability and availability of your application. In addition, it will help in enhancing the performance of the application. By using both Kubernetes and Docker, you can manage your containerized applications at scale.

In conclusion

Kubernetes can manage the orchestration of your containerized applications while Docker can help with the creation of the containers. Docker can help in the packaging, shipping and distribution of your application along with the dependencies in the form of a container. With Kubernetes, you get an orchestration platform that will help in managing these Docker containers and orchestrate them from a control plane.

Throughout the article, you have seen the advantages of using Kubernetes and Docker and their significant differences. Also, you saw how using a combination of both Kubernetes and Docker together can help in the creation and orchestration of your containerized application.

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