Both Docker and Kubernetes are open cloud-native technologies. And, major cloud service providers support components of both Docker and Kubernetes in their managed offerings. The difference between the two is that Docker is about packaging containerized applications on a single node and Kubernetes is meant to run them across a cluster. Since these packages accomplish different things, they are often used in tandem.
Of course, Docker and Kubernetes can be used independently. Whereas a large enterprise may benefit from Kubernetes and can support its maintenance, a smaller project may benefit from just adopting Docker. Or, a company may utilize Docker or OCI containers with another container scheduler. Similarly, Kubernetes is most commonly used with Docker containers, but it can work with other container types and runtimes.
In 2020, Kubernetes announced it would deprecate support for the Docker container engine in favor of other container engines like CRI-O and containerd. This removed the Dockershim to reduce moving parts, but Kubernetes still supports OCI and Docker image formats as well as Docker registries.
What is Docker?
Just as people use Xerox as shorthand for paper copies and say “Google” instead of internet search, Docker has become synonymous with containers.
Docker is more than containers, though. It is a suite of tools for developers to build, share, run and orchestrate containerized apps.
•Developer tools for building container images: Docker Build creates a container image, the blueprint for a container, including everything needed to run an application – the application code, binaries, scripts, dependencies, configuration, environment variables, and so on. Docker Compose is a tool for defining and running multi-container applications. These tools integrate tightly with code repositories (such as GitHub) and continuous integration and continuous delivery (CI/CD) pipeline tools (such as Jenkins).
•Sharing images: Docker Hub is a registry service provided by Docker for finding and sharing container images with your team or the public. Docker Hub is similar in functionality to GitHub.
•Running containers: Docker Engine is a container runtime that runs in almost any environment: Mac and Windows PCs, Linux and Windows servers, the cloud, and on edge devices. Docker Engine is built on top containerd, the leading open-source container runtime, a project of the Cloud Native Computing Foundation (DNCF).
•Built-in container orchestration: Docker Swarm manages a cluster of Docker Engines (typically on different nodes) called a swarm. Here the overlap with Kubernetes begins.
What is Kubernetes?
Kubernetes is an open-source container orchestration platform for managing, automating, and scaling containerized applications. Although Docker Swarm is also an orchestration tool, Kubernetes is the de facto standard for container orchestration because of its greater flexibility and capacity to scale.
Organizations use Kubernetes to automate the deployment and management of containerized applications. Rather than individually managing each container in a cluster, a DevOps team can instead tell Kubernetes how to allocate the necessary resources in advance.
Comparing Docker and Kubernetes
To be truthful, we can’t compare Docker and Kubernetes directly. There are many different tools under the “Docker” name, and Kubernetes is a single project. But if you’re still unsure of the difference, we can probably say:
•Docker is a set of tools for building and running containers, on your laptop, or on a bunch of servers.
•Docker Swarm is Docker’s tool for managing containers on a cluster of servers.
•Kubernetes is a tool for deploying and managing containers on your servers, or in the cloud.
Features of Kubernetes:
•Offers automated scheduling
•Automated rollouts & rollback
•Horizontal Scaling & Load Balancing
•Provides a higher density of resource utilization
•Offers enterprise-ready features
•You can create predictable infrastructure
•Provides declarative configuration
•Deploy and update software at scale
•Offers environment consistency for development, testing, and production
Features of Docker:
•Isolated environments for managing your applications
SUMMARY OF KEY DIFFERENCES
•Kubernetes is developed by Google whereas Docker Swarm is developed by Docker Inc.
•Kubernetes provides Auto-scaling whereas Docker Swarm doesn’t support autoscaling.
•Kubernetes supports up to 5000 nodes whereas Docker Swarm supports more than 2000 nodes.
•Kubernetes is less extensive and customizable whereas Docker Swarm is more comprehensive and highly customizable.
•Kubernetes provides low fault tolerance while Docker provides high fault tolerance.