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+# Docker Basics
+
+Core concepts and workflows for Docker containerization.
+
+## Core Concepts
+
+**Containers:** Lightweight, isolated processes bundling apps with dependencies. Ephemeral by default.
+
+**Images:** Read-only blueprints for containers. Layered filesystem for reusability.
+
+**Volumes:** Persistent storage surviving container deletion.
+
+**Networks:** Enable container communication.
+
+## Dockerfile Best Practices
+
+### Essential Instructions
+```dockerfile
+FROM node:20-alpine              # Base image (use specific versions)
+WORKDIR /app                     # Working directory
+COPY package*.json ./            # Copy dependency files first
+RUN npm install --production     # Execute build commands
+COPY . .                         # Copy application code
+ENV NODE_ENV=production          # Environment variables
+EXPOSE 3000                      # Document exposed ports
+USER node                        # Run as non-root (security)
+CMD ["node", "server.js"]        # Default command
+```
+
+### Multi-Stage Builds (Production)
+```dockerfile
+# Stage 1: Build
+FROM node:20-alpine AS build
+WORKDIR /app
+COPY package*.json ./
+RUN npm install
+COPY . .
+RUN npm run build
+
+# Stage 2: Production
+FROM node:20-alpine AS production
+WORKDIR /app
+COPY --from=build /app/dist ./dist
+COPY --from=build /app/node_modules ./node_modules
+USER node
+EXPOSE 3000
+CMD ["node", "dist/server.js"]
+```
+
+Benefits: Smaller images, improved security, no build tools in production.
+
+### .dockerignore
+```
+node_modules
+.git
+.env
+*.log
+.DS_Store
+README.md
+docker-compose.yml
+dist
+coverage
+```
+
+## Building Images
+
+```bash
+# Build with tag
+docker build -t myapp:1.0 .
+
+# Build targeting specific stage
+docker build -t myapp:dev --target build .
+
+# Build for multiple platforms
+docker buildx build --platform linux/amd64,linux/arm64 -t myapp:1.0 .
+
+# View layers
+docker image history myapp:1.0
+```
+
+## Running Containers
+
+```bash
+# Basic run
+docker run myapp:1.0
+
+# Background (detached)
+docker run -d --name myapp myapp:1.0
+
+# Port mapping (host:container)
+docker run -p 8080:3000 myapp:1.0
+
+# Environment variables
+docker run -e NODE_ENV=production myapp:1.0
+
+# Volume mount (named volume)
+docker run -v mydata:/app/data myapp:1.0
+
+# Bind mount (development)
+docker run -v $(pwd)/src:/app/src myapp:1.0
+
+# Resource limits
+docker run --memory 512m --cpus 0.5 myapp:1.0
+
+# Interactive terminal
+docker run -it myapp:1.0 /bin/sh
+```
+
+## Container Management
+
+```bash
+# List containers
+docker ps
+docker ps -a
+
+# Logs
+docker logs myapp
+docker logs -f myapp          # Follow
+docker logs --tail 100 myapp  # Last 100 lines
+
+# Execute command
+docker exec myapp ls /app
+docker exec -it myapp /bin/sh  # Interactive shell
+
+# Stop/start
+docker stop myapp
+docker start myapp
+
+# Remove
+docker rm myapp
+docker rm -f myapp  # Force remove running
+
+# Inspect
+docker inspect myapp
+
+# Monitor resources
+docker stats myapp
+
+# Copy files
+docker cp myapp:/app/logs ./logs
+```
+
+## Volume Management
+
+```bash
+# Create volume
+docker volume create mydata
+
+# List volumes
+docker volume ls
+
+# Remove volume
+docker volume rm mydata
+
+# Remove unused volumes
+docker volume prune
+```
+
+## Network Management
+
+```bash
+# Create network
+docker network create my-network
+
+# List networks
+docker network ls
+
+# Connect container
+docker network connect my-network myapp
+
+# Disconnect
+docker network disconnect my-network myapp
+```
+
+## Language-Specific Dockerfiles
+
+### Node.js
+```dockerfile
+FROM node:20-alpine AS build
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci --only=production
+COPY . .
+RUN npm run build
+
+FROM node:20-alpine
+WORKDIR /app
+COPY --from=build /app/dist ./dist
+COPY --from=build /app/node_modules ./node_modules
+USER node
+CMD ["node", "dist/server.js"]
+```
+
+### Python
+```dockerfile
+FROM python:3.11-slim AS build
+WORKDIR /app
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+FROM python:3.11-slim
+WORKDIR /app
+COPY --from=build /usr/local/lib/python3.11/site-packages /usr/local/lib/python3.11/site-packages
+COPY . .
+RUN adduser --disabled-password appuser
+USER appuser
+CMD ["python", "app.py"]
+```
+
+### Go
+```dockerfile
+FROM golang:1.21-alpine AS build
+WORKDIR /app
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o main .
+
+FROM scratch
+COPY --from=build /app/main /main
+CMD ["/main"]
+```
+
+## Security Hardening
+
+```dockerfile
+# Use specific versions
+FROM node:20.11.0-alpine3.19
+
+# Create non-root user
+RUN addgroup -g 1001 -S nodejs && \
+    adduser -S nodejs -u 1001
+
+# Set ownership
+COPY --chown=nodejs:nodejs . .
+
+# Switch to non-root
+USER nodejs
+```
+
+## Troubleshooting
+
+### Container exits immediately
+```bash
+docker logs myapp
+docker run -it myapp /bin/sh
+docker run -it --entrypoint /bin/sh myapp
+```
+
+### Cannot connect
+```bash
+docker ps
+docker port myapp
+docker network inspect bridge
+docker inspect myapp | grep IPAddress
+```
+
+### Out of disk space
+```bash
+docker system df
+docker system prune -a
+docker volume prune
+```
+
+### Build cache issues
+```bash
+docker build --no-cache -t myapp .
+docker builder prune
+```
+
+## Best Practices
+
+- Use specific image versions, not `latest`
+- Run as non-root user
+- Multi-stage builds to minimize size
+- Implement health checks
+- Set resource limits
+- Keep images under 500MB
+- Scan for vulnerabilities: `docker scout cves myapp:1.0`
+
+## Quick Reference
+
+| Task | Command |
+|------|---------|
+| Build | `docker build -t myapp:1.0 .` |
+| Run | `docker run -d -p 8080:3000 myapp:1.0` |
+| Logs | `docker logs -f myapp` |
+| Shell | `docker exec -it myapp /bin/sh` |
+| Stop | `docker stop myapp` |
+| Remove | `docker rm myapp` |
+| Clean | `docker system prune -a` |
+
+## Resources
+
+- Docs: https://docs.docker.com
+- Best Practices: https://docs.docker.com/develop/dev-best-practices/
+- Dockerfile Reference: https://docs.docker.com/engine/reference/builder/