Demos

OpenGSLB includes a comprehensive set of interactive demos that showcase its features and capabilities. Each demo builds on the previous one, introducing new concepts progressively.

Demo Overview

Demo	Focus Area	Key Features
Demo 1: Standalone	Basic Setup	DNS load balancing, health checks, round-robin
Demo 2: Agent-Overwatch	Distributed Architecture	Proactive draining, agent gossip, zero-downtime
Demo 3: Latency Routing	Performance Optimization	Latency-based routing, automatic adaptation
Demo 4: GeoIP Routing	Geographic Distribution	GeoIP routing, EDNS Client Subnet, custom CIDR
Demo 5: Predictive Health	Proactive Health	Predictive monitoring, chaos engineering, Grafana
Demo 6: Passive Latency Learning	Real Client Latency	TCP RTT learning, subnet aggregation, Azure multi-region

Prerequisites

All demos require:

Docker and Docker Compose
Go 1.22+ (for building OpenGSLB)
Basic CLI tools: dig, curl, jq

Building the Binary

Each demo requires the OpenGSLB binary built for Alpine Linux (musl libc):

# From the repository root
CGO_ENABLED=0 GOOS=linux go build -o opengslb ./cmd/opengslb

# Copy to the specific demo directory
cp opengslb demos/demo-X-*/bin/

Note

The CGO_ENABLED=0 flag is required because demo containers use Alpine Linux with musl libc instead of glibc.

Running a Demo

Each demo follows a consistent pattern:

# Navigate to the demo directory
cd demos/demo-X-*/

# Start the environment
docker-compose up -d --build

# SSH into the client container (password: demo)
ssh -p 2222 root@localhost

# Run the guided demo script
./demo.sh

# Stop the demo
docker-compose down -v

Learning Path

Beginner: Start with Demo 1

If you’re new to OpenGSLB, start with Demo 1: Standalone. It introduces:

Basic DNS load balancing concepts
Health check configuration
The Overwatch component

Intermediate: Demos 2 & 3

Once comfortable with the basics, explore:

Demo 2: Learn about the agent-overwatch architecture and proactive health signaling
Demo 3: Understand latency-based routing and automatic traffic optimization

Advanced: Demos 4, 5 & 6

For production-ready scenarios:

Demo 4: Geographic routing with GeoIP databases and custom CIDR mappings
Demo 5: Predictive health monitoring with chaos engineering
Demo 6: Passive latency learning with real TCP RTT data (requires Azure)

Demo Architecture Comparison

Demo 1: Simple               Demo 2-5: Distributed
─────────────────           ─────────────────────────

  ┌──────────┐                 ┌──────────┐
  │ Overwatch│◄────┐           │ Overwatch│◄──────────┐
  └────┬─────┘     │           └────┬─────┘           │
       │           │                │         Gossip  │
       │ Health    │                │                 │
       │ Checks    │                ▼                 │
       ▼           │           ┌─────────┐      ┌─────────┐
  ┌─────────┐      │           │ Backend │      │ Backend │
  │ Backend │      │           │ + Agent │      │ + Agent │
  │ (nginx) │──────┘           └─────────┘      └─────────┘
  └─────────┘

Troubleshooting

Common Issues

Binary not found

# Rebuild with correct flags
CGO_ENABLED=0 GOOS=linux go build -o demos/demo-X-*/bin/opengslb ./cmd/opengslb

Permission denied on config

# Config files require 600 permissions - rebuild the container
docker-compose build
docker-compose up -d

DNS queries fail

# Check if Overwatch is running
docker-compose ps
docker-compose logs overwatch

Port conflicts

# Stop all demos first
docker-compose down -v

# Check for conflicting services
lsof -i :2222 -i :8080 -i :9090