What is the difference between Docker and Kubernetes?

Docker is a platform for developing, delivering, and running applications using containers. It focuses on isolating the application and its dependencies within a container, ensuring environment reproducibility.

Kubernetes is a container orchestration system that automates deployment, scaling, and management of containerized applications. It works with Docker (among other container runtimes), providing infrastructure to run and manage multiple containers in a cluster at a higher level.

Key differences:

Aspect	Docker	Kubernetes
Purpose	Containerization and application isolation	Orchestration and management of containers
Scope	Single container/host	Cluster of multiple hosts
Management	Creating, starting, stopping containers	Automated deployment, scaling, load balancing, self-healing
Level	Low level (container)	High level (system of containers)
Dependency	Can be used without Kubernetes	Often uses Docker as the runtime environment

Example of using Docker:

# Example Dockerfile for creating an image
FROM ubuntu:latest
RUN apt-get update && apt-get install -y nginx
COPY html /var/www/html
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

Example of using Kubernetes (Pod definition):

# Example Pod definition in Kubernetes
apiVersion: v1
kind: Pod
metadata:
  name: my-nginx-pod
spec:
  containers:
  - name: nginx-container
    image: nginx:latest # Uses Docker image
    ports:
    - containerPort: 80

Thus, Docker creates "boxes" for applications (containers), and Kubernetes manages how these boxes work together in a large distributed system. Kubernetes does not replace Docker but works alongside it to ensure reliable and scalable deployment.