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Docker - Containers

Introduction to Docker

Docker is a container platform that allows packaging applications and their dependencies in lightweight and portable containers. This facilitates development, deployment and scaling of applications.

Fundamental concepts

Containers

Containers are isolated environments that contain everything needed to run an application.

Images

Images are read-only templates used to create containers.

Dockerfile

A Dockerfile is a script containing instructions to build an image.

# Example Dockerfile
FROM ubuntu:20.04
RUN apt-get update && apt-get install -y nginx
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

Basic commands

Image management

# Build an image
docker build -t my-application .

# List images
docker images

# Remove an image
docker rmi my-application

Container management

# Run a container
docker run -d -p 8080:80 my-application

# List containers
docker ps

# Stop a container
docker stop <container_id>

# Remove a container
docker rm <container_id>

Docker Compose

Docker Compose allows defining and running multi-container applications.

# docker-compose.yml
version: '3.8'
services:
  web:
    build: .
    ports:
      - "8080:80"
  db:
    image: postgres:13
    environment:
      POSTGRES_DB: myapp
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password

Use cases

  • Local development
  • Application deployment
  • Microservices
  • CI/CD pipelines

Next steps

In the following sections we will explore: - Image optimization - Docker networks - Volumes and persistence - Container security - Orchestration with Kubernetes

Additional resources

Official documentation

Community