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DockervsKubernetes
What is the difference between Docker and Kubernetes?
Updated 2 min read8 differences
In short
Docker builds container images and runs containers on one machine, while Kubernetes runs them across a cluster, handling scheduling, scaling and self-healing.
Docker
Docker is an open-source platform for packaging an application and everything it needs into a container that runs the same way on any machine.
Read the page on DockerKubernetes
Kubernetes is an open-source system that automates deploying, scaling, and managing containerized applications across a cluster of machines.
Read the page on KubernetesDocker and Kubernetes compared
| Aspect | Docker | Kubernetes |
|---|---|---|
| What it is | A tool to build images and run containers | A platform to orchestrate containers across machines |
| Scope | One host | A cluster of many nodes |
| Main unit | A container, or a multi-container app with Compose | A pod, managed through Deployments and Services |
| Scaling | Manual: you start more containers yourself | Automatic horizontal scaling based on load |
| Self-healing | Restart policies on a single machine | Reschedules failed pods onto healthy nodes |
| Configuration | A Dockerfile and a compose.yaml file | YAML manifests that describe the desired state |
| Learning curve | Gentle; productive within a day | Steep; many concepts and moving parts |
| Best for | Local development, CI and small deployments | Large production systems with many services |
The difference, explained
Docker is a set of tools for packaging an application into a container image with a Dockerfile and running that image as a container on one host. Kubernetes is an open-source orchestration platform: you describe the desired state, such as 'run three copies of this image behind one address', and it keeps a cluster of machines matching that description.
They work at different levels. Docker answers 'how do I package and run this app?', while Kubernetes answers 'how do I run hundreds of containers reliably across many servers?' Kubernetes restarts failed containers, spreads them across nodes, rolls out new versions gradually and scales them with load, which a single Docker host does not do by itself.
They are complementary, not competitors. A common workflow is to build images with Docker, push them to a container registry, and let Kubernetes pull and run them in production. Kubernetes runs containers through runtimes such as containerd that follow the OCI standard, so images built with Docker work unchanged.
A common misconception is that Kubernetes dropped Docker and Docker images no longer work there. In 2022 Kubernetes removed dockershim, a built-in adapter for the Docker Engine, but images built with Docker are standard OCI images and still run everywhere. Another is that every project needs Kubernetes: for a small app, Docker Compose or a managed container service is often enough.
Which one should you use?
Choose Docker when…
- You are packaging an app or setting up a local development environment.
- Your app runs on one server with a few containers.
- You want consistent, reproducible builds in CI.
Choose Kubernetes when…
- You run many services that need automatic scaling and self-healing.
- Your app must stay available when individual machines fail.
- Several teams deploy independently onto shared infrastructure.
- You want rolling updates and declarative, version-controlled deployments.
Running an app with each tool
# Docker: build an image and run one container on this machine
docker build -t shop:1.0 .
docker run -d -p 8080:80 shop:1.0
# If this machine goes down, so does the app# Kubernetes: declare what you want; the cluster keeps it true
kubectl create deployment shop --image=registry.example.com/shop:1.0 --replicas=3
kubectl expose deployment shop --port=80 --type=LoadBalancer
# Scale out and let Kubernetes place the new pods on healthy nodes
kubectl scale deployment shop --replicas=10Readers ask
Do I need Docker to use Kubernetes?
No. Kubernetes runs containers through runtimes like containerd or CRI-O, and it can run images built by any OCI-compatible tool, including Docker.
Is Kubernetes replacing Docker?
No. They do different jobs: Docker is mostly used to build and run containers during development, while Kubernetes runs them at scale in production.
How is Docker Compose different from Kubernetes?
Docker Compose runs a group of related containers on one machine from a single file, which is great for development. Kubernetes manages containers across a cluster, with scaling and failover built in.