Tickets

A Go-based event ticketing system demonstrating event-driven architecture patterns including CQRS, Event Sourcing, and the Outbox Pattern.

Live Demo

• Application: https://tickets.previewhub.app/
• Container Logs: https://dozzle.previewhub.app/
• Jaeger Dashboard: https://jaeger.previewhub.app/

Features

• Ticket Management - Create, track, and manage event tickets
• Show Management - Configure shows with external provider integration (Dead Nation)
• Booking System - Book tickets for shows with confirmation workflows
• Refund Processing - Handle ticket cancellations with receipt voiding and payment refunds
• Event-Driven Architecture - Loosely coupled components communicating via events and commands
• Observability - Distributed tracing, metrics, and health checks

Demo Screenshots

Shows Management

Create and manage shows with Dead Nation integration

Ticket Booking

Book tickets for available shows

Tickets Overview

View and manage tickets

Operations Report

Monitor bookings and operations with detailed reporting

Architecture

Key Patterns

• CQRS (Command Query Responsibility Segregation) - Separate command and event buses
• Event Sourcing - Events as the source of truth for state changes
• Outbox Pattern - Reliable event publishing with PostgreSQL-based outbox
• Read Models - Denormalized views for efficient queries (e.g., ops bookings)

External Integrations

• Dead Nation API - External ticket booking provider
• Receipts Service - Issue and void receipts
• Payments Service - Process refunds
• Files API - Upload ticket files
• Spreadsheets API - Track tickets for printing/refunding

Tech Stack

Component	Technology
Language	Go 1.25.5
HTTP Framework	Echo v4
Event Bus	Watermill
Message Broker	Redis Streams
Database	PostgreSQL
Cache	Redis
Tracing	OpenTelemetry + Jaeger
Metrics	Prometheus

Project Structure

tickets/
├── cmd/server/         # Application entrypoint
├── adapters/           # External service adapters (Dead Nation, Payments, Receipts, Files)
├── db/                 # Database repositories and migrations
├── entities/           # Domain entities, events, and commands
├── http/               # HTTP handlers and routing
├── message/
│   ├── command/        # Command bus configuration and handlers
│   ├── event/          # Event bus configuration and handlers
│   └── outbox/         # Outbox pattern implementation
├── observability/      # Tracing and metrics configuration
├── service/            # Service composition and startup
├── tests/              # Component and integration tests
└── docker/             # Docker configuration (Prometheus)

Getting Started

Prerequisites

• Go 1.25.5+
• Docker & Docker Compose

Environment Setup

Create .env.local for development:

POSTGRES_URL=postgres://user:password@localhost:5432/db?sslmode=disable
REDIS_URL=localhost:6379
GATEWAY_URL=http://localhost:8888
OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318

Create .env.test for testing with similar configuration.

Running with Docker

# Start all dependencies (PostgreSQL, Redis, Prometheus, Jaeger)
make docker-up

# Stop and remove volumes
make docker-down

Development

# Run the server
make dev

# Run tests
make test

# Run tests with verbose output
make test-verbose

# Run linter
make lint

API Endpoints

Ticket Operations

Method	Endpoint	Description
GET	/api/tickets	List all tickets
POST	/api/tickets-status	Update ticket status
PUT	/api/ticket-refund/:ticket_id	Initiate ticket refund

Show Management

Method	Endpoint	Description
POST	/api/shows	Create a new show

Booking Operations

Method	Endpoint	Description
POST	/api/book-tickets	Book tickets for a show

Operations & Monitoring

Method	Endpoint	Description
GET	/api/ops/bookings	List all bookings (with optional date filter)
GET	/api/ops/bookings/:id	Get booking by ID
GET	/health	Health check
GET	/metrics	Prometheus metrics

Events

The system publishes and handles the following events:

• TicketBookingConfirmed_v1 - Ticket booking confirmed
• TicketBookingCanceled_v1 - Ticket booking canceled
• TicketPrinted_v1 - Ticket file generated
• TicketReceiptIssued_v1 - Receipt issued for ticket
• TicketRefunded_v1 - Ticket refund completed
• BookingMade_v1 - Booking created for a show

Commands

• RefundTicket - Initiates the ticket refund process

Testing

# Run all tests
make test

# Run with verbose output
make test-verbose

Tests cover:

• Component integration tests
• Ticket booking workflows
• Show booking workflows
• Ticket cancellation flows
• Refund processing

Observability

Jaeger (Tracing)

• Local: Access the Jaeger UI at http://localhost:16686 to view distributed traces
• Live Demo: https://jaeger.previewhub.app/

Prometheus (Metrics)

Access Prometheus at http://localhost:9090. Metrics are exposed at /metrics.

Docker Services

Service	Port	Description	Live Demo
Application	8080	Main application	tickets.previewhub.app
Gateway	8888	Event-driven gateway	-
PostgreSQL	5432	Database	-
Redis	6379	Message broker & cache	-
Prometheus	9090	Metrics collection	-
Jaeger	16686	Tracing UI	jaeger.previewhub.app
Jaeger OTLP	4318	OTLP collector	-
Dozzle	-	Container logs viewer	dozzle.previewhub.app