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Installare Docker e gestire container su Debian 12

Guida pratica per installare Docker, creare Dockerfile e orchestrare servizi con Docker Compose.

1. Installazione Docker

apt install -y ca-certificates curl gnupg
install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/debian bookworm stable" > /etc/apt/sources.list.d/docker.list
apt update && apt install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin

2. Verifica

docker run hello-world
docker compose version

3. Esempio: Nginx + MySQL con Docker Compose

mkdir -p ~/myapp && cd ~/myapp
cat > docker-compose.yml <<EOF
services:
  web:
    image: nginx:alpine
    ports:
      - "8080:80"
    volumes:
      - ./html:/usr/share/nginx/html:ro
    depends_on:
      - db

  db:
    image: mariadb:11
    environment:
      MYSQL_ROOT_PASSWORD: password123
      MYSQL_DATABASE: myapp
    volumes:
      - db_data:/var/lib/mysql

volumes:
  db_data:
EOF

mkdir html && echo "<h1>Funziona!</h1>" > html/index.html
docker compose up -d

4. Comandi essenziali

docker compose ps          # Stato container
docker compose logs -f     # Log in tempo reale
docker compose down        # Ferma e rimuovi
docker compose pull        # Aggiorna immagini
docker system prune -af    # Pulizia spazio

5. Dockerfile personalizzato

cat > Dockerfile <<EOF
FROM python:3.11-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
EXPOSE 5000
CMD ["python", "app.py"]
EOF

docker build -t myapp:latest .
docker run -d -p 5000:5000 myapp:latest

6. Volumi e persistenza

# Backup volume
docker run --rm -v db_data:/data -v $(pwd):/backup alpine tar czf /backup/db_backup.tar.gz /data

# Restore
docker run --rm -v db_data:/data -v $(pwd):/backup alpine tar xzf /backup/db_backup.tar.gz -C /

Risultato: Docker e Docker Compose operativi per deploy rapido di qualsiasi servizio containerizzato.