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Docker

Docker packages applications and their dependencies into containers.

What Is Docker​

Docker containers provide a consistent runtime environment across development, testing, and production.

They are useful when an application needs predictable dependencies, services, and deployment behavior.

How To Use Docker​

Write a Dockerfile, build an image, and run a container from that image.

Basic Example​

FROM node:22-alpine
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
CMD ["npm", "start"]

Common Concepts​

  • Images are packaged application snapshots.
  • Containers are running image instances.
  • Volumes persist data.
  • Compose runs multi-service local environments.

What To Learn Next​

Learn image layers, Docker Compose, networking, volumes, registries, and production container security.