2024-09-06
Docker Containerization: Building, Shipping, and Running Applications
Complete guide to Docker containerization, from basic concepts to production deployment strategies.
Docker revolutionized application deployment by making it easy to package applications with all their dependencies. This guide covers everything from Docker basics to advanced orchestration and production best practices.
Docker Fundamentals
Core Docker concepts and commands:
# Pull and run an image
docker pull nginx:latest
docker run -d -p 80:80 nginx
# Container management
docker ps # List running containers
docker ps -a # List all containers
docker stop container_id # Stop container
docker rm container_id # Remove container
# Image management
docker images # List images
docker rmi image_id # Remove image
docker build -t myapp . # Build image from Dockerfile
Writing Effective Dockerfiles
Multi-stage Build Example
# Stage 1: Build
FROM node:18-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production
COPY . .
RUN npm run build
# Stage 2: Production
FROM node:18-alpine
WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
EXPOSE 3000
CMD ["node", "dist/index.js"]
Dockerfile Best Practices
• Use specific base image tags (not :latest)
• Minimize layers by combining RUN commands
• Order instructions from least to most frequently changing
• Use .dockerignore to exclude unnecessary files
• Run as non-root user for security
• Use COPY instead of ADD unless you need tar extraction
Docker Compose
Multi-container application with docker-compose.yml:
version: '3.8'
services:
web:
build: .
ports:
- "3000:3000"
environment:
- NODE_ENV=production
- DB_HOST=postgres
depends_on:
- postgres
- redis
postgres:
image: postgres:15
volumes:
- postgres_data:/var/lib/postgresql/data
environment:
- POSTGRES_PASSWORD=secret
redis:
image: redis:7-alpine
command: redis-server --appendonly yes
volumes:
- redis_data:/data
volumes:
postgres_data:
redis_data:
Container Networking
# Create custom network
docker network create myapp-network
# Run containers on same network
docker run -d --name db --network myapp-network postgres
docker run -d --name app --network myapp-network myapp
# Containers can communicate using container names
# Inside app container: postgres://db:5432/mydb
# List networks
docker network ls
# Inspect network
docker network inspect myapp-network
Volume Management
# Named volumes (managed by Docker)
docker volume create mydata
docker run -v mydata:/app/data myapp
# Bind mounts (host directory)
docker run -v /host/path:/container/path myapp
# Read-only volumes
docker run -v /host/path:/container/path:ro myapp
# Volume management
docker volume ls # List volumes
docker volume inspect mydata # Inspect volume
docker volume prune # Remove unused volumes
Production Best Practices
Security Scanning
Use `docker scan` or tools like Trivy to scan images for vulnerabilities.
Resource Limits
Set memory and CPU limits: `docker run -m 512m --cpus="1.5" myapp`
Health Checks
Implement HEALTHCHECK in Dockerfile to monitor container health.
Logging
Use centralized logging with drivers like json-file, syslog, or fluentd.
Published on 2024-09-06 • Category: DevOps
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