Docker

Definition

Docker is an open-source containerization platform that allows developers to package applications and their dependencies into standardized containers, ensuring consistent execution across any environment.

Core Concepts

• Image: A read-only template containing everything needed to run an application
• Container: A running instance of an image, an independent and isolated runtime environment
• Dockerfile: A script defining how to build an image
• Registry: A service for storing and distributing images (e.g., Docker Hub)

Dockerfile Example

# Multi-stage build example
FROM python:3.11.7-slim as builder
WORKDIR /app
COPY requirements.txt .
RUN pip install --user -r requirements.txt

FROM python:3.11.7-slim
WORKDIR /app
COPY --from=builder /root/.local /root/.local
COPY . .
EXPOSE 8000
CMD ["python", "app.py"]

Common Commands

docker build -t myapp .        # Build image
docker run -d -p 80:80 myapp  # Run container
docker ps                      # List running containers
docker logs <container>        # View container logs
docker exec -it <container> sh # Enter container shell