Docker Stack Setup¶

Install Docker and Docker Compose on Ubuntu, then deploy a simple multi-container stack.

What This Does¶

This scenario demonstrates:

Installing Docker Engine from official Docker repository
Installing Docker Compose plugin
Building a custom Flask application image
Orchestrating multiple containers with docker-compose
Setting up nginx as a reverse proxy for the Flask app
Container networking and health checks
Managing user permissions for Docker

Prerequisites¶

Ubuntu 20.04 or later
Root/sudo access
Mooncake installed
Internet connection

Files¶

setup.yml - Main deployment playbook
files/app.py - Flask web application
files/Dockerfile - Container image definition
templates/docker-compose.yml.j2 - Multi-container orchestration config
templates/nginx.conf.j2 - Nginx reverse proxy configuration

How to Run¶

# Run the setup
mooncake run setup.yml

# Or with custom settings
mooncake run setup.yml --var project_name=mystack --var nginx_port=9090

Variables¶

You can customize these variables:

project_name (default: mooncake-stack) - Project name
project_dir (default: /opt/{{ project_name }}) - Project directory
app_port (default: 5000) - Flask application port
nginx_port (default: 8080) - Nginx public port
docker_user (default: current user) - User to add to docker group

What Gets Deployed¶

Docker Components¶

Docker Engine (latest stable)
Docker Compose plugin
containerd runtime
Docker Buildx plugin

Container Stack¶

Flask App Container - Python web application
Nginx Container - Reverse proxy and load balancer

Network¶

Custom bridge network for container communication
Port mappings for external access

Stack Architecture¶

Internet
    |
    | :8080
    v
[Nginx Container]
    |
    | internal network
    |
    v
[Flask App Container] :5000

Using Your Stack¶

Access the Application¶

# Through nginx (production-like)
curl http://localhost:8080

# Direct app access
curl http://localhost:5000

# API endpoints
curl http://localhost:8080/api/info
curl http://localhost:8080/api/health
curl http://localhost:8080/api/env

Docker Compose Commands¶

cd /opt/mooncake-stack

# View running containers
sudo docker compose ps

# View logs
sudo docker compose logs
sudo docker compose logs -f        # Follow logs
sudo docker compose logs app       # Specific service

# Restart services
sudo docker compose restart
sudo docker compose restart app    # Specific service

# Stop the stack
sudo docker compose down

# Stop and remove volumes
sudo docker compose down -v

# Rebuild and restart
sudo docker compose up -d --build

# Scale services (if stateless)
sudo docker compose up -d --scale app=3

Docker Commands¶

# List all containers
sudo docker ps -a

# View container stats
sudo docker stats

# Execute command in container
sudo docker exec -it mooncake-stack-app bash

# View container logs
sudo docker logs mooncake-stack-app

# Inspect container
sudo docker inspect mooncake-stack-app

# View images
sudo docker images

# Remove unused resources
sudo docker system prune

Using Docker Without Sudo¶

After setup, you'll need to re-login or run:

newgrp docker

Then you can use docker without sudo:

docker ps
docker compose ps

Project Structure¶

/opt/mooncake-stack/
├── docker-compose.yml    # Orchestration config
├── nginx.conf            # Nginx configuration
└── app/
    ├── Dockerfile        # Image definition
    └── app.py           # Flask application

Customizing the Application¶

Modify Flask App¶

sudo nano /opt/mooncake-stack/app/app.py

Rebuild and Deploy¶

cd /opt/mooncake-stack
sudo docker compose up -d --build

Add Environment Variables¶

Edit docker-compose.yml:

services:
  app:
    environment:
      - MY_VAR=value
      - DATABASE_URL=postgresql://...

Monitoring and Debugging¶

Check Container Health¶

sudo docker compose ps
sudo docker inspect mooncake-stack-app | grep -A 10 Health

View Resource Usage¶

sudo docker stats

Troubleshooting¶

# View detailed logs
sudo docker compose logs --tail=100

# Check if containers are running
sudo docker compose ps

# Restart problematic service
sudo docker compose restart app

# Rebuild from scratch
sudo docker compose down
sudo docker compose up -d --build

# Check Docker daemon status
sudo systemctl status docker

# View Docker daemon logs
sudo journalctl -u docker -f

Cleanup¶

To remove the stack:

# Stop and remove containers
cd /opt/mooncake-stack
sudo docker compose down

# Remove project directory
sudo rm -rf /opt/mooncake-stack

# Remove Docker images
sudo docker rmi mooncake-stack-app nginx:alpine python:3.11-slim

# Optionally remove Docker completely
sudo systemctl stop docker
sudo apt-get remove --purge docker-ce docker-ce-cli containerd.io docker-compose-plugin
sudo rm -rf /var/lib/docker

Learning Points¶

This example teaches:

Installing Docker from official repositories
Building custom Docker images with Dockerfile
Multi-container orchestration with Docker Compose
Container networking and service discovery
Reverse proxy configuration with Nginx
Container health checks
Volume management
Docker security basics (user groups)
Container logs and monitoring

Production Considerations¶

For production deployments, also consider:

Security:
Use specific image tags, not latest
Scan images for vulnerabilities
Run containers as non-root users
Use secrets management
Reliability:
Implement proper health checks
Configure restart policies
Set resource limits (CPU, memory)
Use volume backups
Monitoring:
Centralized logging (ELK, Grafana Loki)
Metrics collection (Prometheus)
Alerting (Alertmanager)
Scaling:
Load balancing across multiple instances
Container orchestration (Kubernetes)
Database connection pooling
Caching layers (Redis)

Next Steps¶

After deployment, try:

Adding a PostgreSQL database service
Implementing Redis for caching
Adding more API endpoints
Setting up SSL with Let's Encrypt
Deploying your own application
Exploring Docker Swarm or Kubernetes
Adding monitoring with Prometheus and Grafana