🎟️ Ticketmaster – Microservices Backend

A production-grade, event-driven microservices system inspired by Ticketmaster, built with Java 21 and Spring Boot 3.2. The system covers the full ticket-booking lifecycle: event discovery → seat reservation → payment processing → notification delivery.

Architecture Overview

                          ┌─────────────────────────────────────────────┐
  Browser / Mobile App    │              Client Layer                    │
                          └──────────────────┬──────────────────────────┘
                                             │ HTTP
                          ┌──────────────────▼──────────────────────────┐
                          │        Nginx (Reverse Proxy / LB)           │
                          │   Rate limiting · Gzip · Security Headers    │
                          └──────────────────┬──────────────────────────┘
                                             │
                          ┌──────────────────▼──────────────────────────┐
                          │     Spring Cloud API Gateway (:8080)        │
                          │  JWT Auth Filter · Rate Limiter (Redis)     │
                          │  Circuit Breaker · Service Discovery        │
                          └──────┬──────┬──────┬──────┬──────┬─────────┘
                                 │      │      │      │      │
             ┌───────────────────┘      │      │      │      └──────────────────┐
             │                          │      │      │                         │
   ┌─────────▼──────┐   ┌───────────────▼──┐   │  ┌───▼───────────┐  ┌────────▼──────────┐
   │  user-service  │   │  event-service   │   │  │payment-service│  │notification-service│
   │    (:8081)     │   │     (:8082)      │   │  │   (:8084)     │  │      (:8085)       │
   └────────────────┘   └──────────────────┘   │  └───────────────┘  └───────────────────┘
                                               │
                                    ┌──────────▼──────────┐
                                    │  booking-service    │
                                    │      (:8083)        │
                                    └─────────────────────┘

  ┌────────────────────────────────────────────────────────────────────────────────┐
  │                            Infrastructure Layer                               │
  │   PostgreSQL (per-service DB) · Redis (Cache + Distributed Lock)              │
  │   Apache Kafka (Event Broker) · Eureka Service Registry                       │
  │   Prometheus + Grafana (Observability) · Kafka UI                             │
  └────────────────────────────────────────────────────────────────────────────────┘

Design Patterns Applied

Pattern	Usage
Database per Service	Each microservice owns its isolated PostgreSQL database
Domain-Driven Design (DDD)	All services use `interfaces / application / domain / infrastructure` layering
CQRS	Command handlers (write) separated from query handlers (read)
Event-Driven Architecture	Services communicate asynchronously via Apache Kafka
Saga Pattern	Booking → Payment saga with compensating transactions (cancel on failure)
Distributed Lock	Redis Redisson locks prevent double-booking of seats
Circuit Breaker	Resilience4j at API Gateway protects downstream services
Outbox / DLQ	Dead Letter Queues for guaranteed message delivery
Cache-Aside	Redis caching for seat maps and event details (high-read traffic)

Tech Stack

Core

Technology	Version	Role
Java	21 (LTS)	Primary language
Spring Boot	3.2.5	Application framework
Spring Cloud	2023.0.1	Microservices infrastructure
Maven	3.x	Multi-module build system

Spring Cloud Components

Component	Purpose
Spring Cloud Gateway	API Gateway, JWT filter, rate limiting
Spring Cloud Netflix Eureka	Service registry & discovery
Spring Cloud Circuit Breaker (Resilience4j)	Fault tolerance
Spring Cloud LoadBalancer	Client-side load balancing

Infrastructure

Technology	Version	Role
PostgreSQL	16	Primary relational database (one DB per service)
Redis	7	Caching, rate limiting, distributed locking
Apache Kafka	7.6.0 (Confluent)	Async event streaming
Zookeeper	7.6.0	Kafka coordination
Liquibase	—	Database schema migrations

Libraries & Tools

Library	Role
JJWT 0.12.5	JWT token generation & validation
Redisson 3.29	Redis distributed lock client
Stripe Java 25.3	Online payment processing
MapStruct 1.5.5	Object mapping (DTO ↔ Entity)
Lombok 1.18.32	Boilerplate reduction
Quartz	Persistent job scheduling (booking expiry)
Thymeleaf	HTML email templates

Observability

Tool	Version	Role
Prometheus	2.51	Metrics collection
Grafana	10.4.2	Metrics dashboards
Spring Boot Actuator	—	Health checks & metrics endpoint
Kafka UI	latest	Kafka topic browser

Services

1. `api-gateway` (Port 8080)

Entry point for all client requests. Responsibilities:

JWT Authentication Filter – validates Bearer token, injects X-User-Id and X-User-Email headers downstream
Rate Limiting – Redis-based token bucket (10 req/s auth, 50 req/s events, 20 req/s bookings)
Circuit Breaker – per-service fallback with Resilience4j
Routing – path-based routing to all downstream services
CORS – configurable allowed origins

2. `user-service` (Port 8081)

Identity & Access Management:

User registration, login, profile management
JWT access token (24h) + refresh token (7d)
Password hashing with BCrypt
Redis cache for user session tokens

3. `event-service` (Port 8082)

Event & Venue Management:

CRUD for Venues (stadium, theatre, arena)
CRUD for Events (concerts, sports, shows)
Seat map generation per section/row
Full-text search by keyword, city, category with pagination
Redis cache for seat maps (high-traffic read)
Kafka consumer: updates seat status from booking-service

Event Status State Machine: DRAFT → PUBLISHED → SOLD_OUT / CANCELLED

Seat Status State Machine: AVAILABLE → LOCKED → BOOKED / AVAILABLE (released)

4. `booking-service` (Port 8083)

Ticket Booking Orchestrator:

Distributed seat locking with Redis Redisson (configurable TTL)
Atomic multi-seat reservation with idempotency checks
2-minute payment window enforced by Quartz persistent scheduler
Booking status machine: PENDING_PAYMENT → CONFIRMED / CANCELLED / EXPIRED
Publishes booking.created, booking.confirmed, booking.cancelled, booking.expired to Kafka
Consumes payment.processed / payment.failed from Kafka
SSE (Server-Sent Events) endpoint for real-time booking status updates to clients

5. `payment-service` (Port 8084)

Payment Processing:

Stripe integration (PaymentIntent, webhooks)
Consumes booking.created → initiates Stripe payment
Publishes payment.processed / payment.failed / payment.refunded
Idempotency keys prevent duplicate charges
Webhook signature verification

6. `notification-service` (Port 8085)

Notification Delivery:

Consumes Kafka events: booking.created, booking.confirmed, booking.cancelled, payment.failed
Sends HTML emails via SMTP (Thymeleaf templates: booking-confirmed.html, payment-failed.html)
SSE push notifications to connected clients
Persists notification history in notification_db

7. `service-registry` (Port 8761)

Netflix Eureka server for service discovery and registration. All microservices register here and resolve each other by name.

8. `common-lib`

Shared library (no separate process). Contains:

Common DTOs, exceptions, security utilities, response wrappers
Shared Kafka event schemas

Port Mapping

Service	Default Port	Description
Nginx	`80`	Public entry point (production)
API Gateway	`8080`	Main developer entry point
User Service	`8081`	Auth & user management
Event Service	`8082`	Events, venues, seats
Booking Service	`8083`	Seat reservation & booking
Payment Service	`8084`	Stripe payment processing
Notification Service	`8085`	Email & SSE notifications
Service Registry (Eureka)	`8761`	Service discovery dashboard
PostgreSQL	`5432`	Database (all service DBs)
Redis	`6379`	Cache & distributed lock
Kafka	`29092`	Kafka broker (external)
Kafka UI	`8090`	Topic & message browser
Prometheus	`9090`	Metrics scraping
Grafana	`3000`	Dashboards

Kafka Topics

Topics are auto-created on startup by kafka-init container via kafka-setup.sh.

Topic	Partitions	Producer	Consumers
`booking.created`	3	booking-service	payment-service, notification-service
`booking.confirmed`	3	booking-service	notification-service, event-service
`booking.cancelled`	3	booking-service	notification-service, event-service
`booking.expired`	3	booking-service	notification-service, event-service
`payment.processed`	3	payment-service	booking-service, notification-service
`payment.failed`	3	payment-service	booking-service, notification-service
`payment.refunded`	3	payment-service	notification-service
`seat.status.changed`	6	booking-service	event-service
`notification.email`	3	notification-service	notification-service
`notification.push`	3	notification-service	notification-service
`dlq.booking`	1	—	(manual inspection)
`dlq.payment`	1	—	(manual inspection)
`dlq.notification`	1	—	(manual inspection)

seat.status.changed uses 6 partitions for parallel consumption due to high traffic volume.
DLQ topics retain messages for 30 days (vs. 7 days for normal topics).

Database Design

Each service owns its isolated PostgreSQL database (Database-per-Service pattern):

Database	Service	Key Tables
`user_db`	user-service	`users`, `refresh_tokens`
`event_db`	event-service	`venues`, `events`, `sections`, `seats`
`booking_db`	booking-service	`bookings`, `booking_items`, `QRTZ_*`
`payment_db`	payment-service	`payments`, `payment_transactions`
`notification_db`	notification-service	`notifications`, `notification_logs`

All databases use UTF-8 encoding, uuid-ossp and pgcrypto extensions, and are managed via Liquibase migrations.

Prerequisites

Docker 24+ and Docker Compose v2
Java 21 (JDK, for local development without Docker)
Maven 3.9+ (for local development)
Stripe account (for payment testing) – Get test keys
An SMTP server for emails (Gmail, SendGrid, Mailhog for local dev, etc.)

Quick Start

1. Clone the repository

git clone https://github.com/Thanh14013/ticketmaster.git
cd ticketmaster

2. Configure environment variables

Copy the example env file and fill in the values:

cp .env.example .env

Edit .env with your configuration (see Environment Variables section below).

3. Start all services

docker compose up -d

Docker Compose starts services in the correct dependency order:

PostgreSQL + Redis + Zookeeper
  → Kafka → kafka-init (creates topics)
    → service-registry
      → api-gateway
        → user-service, event-service, booking-service, payment-service, notification-service

4. Verify services are running

docker compose ps

All services should show healthy. Check the Eureka dashboard:

http://localhost:8761

5. Run a quick health check

curl http://localhost:8080/actuator/health

Rebuild after code changes

docker compose up -d --build

Stop and clean up

# Stop containers (keep volumes)
docker compose down

# Stop and remove all data volumes
docker compose down -v

Environment Variables

Create a .env file in the project root:

# ── Spring ──────────────────────────────────────────────────────
SPRING_PROFILES_ACTIVE=docker

# ── PostgreSQL ───────────────────────────────────────────────────
POSTGRES_HOST=postgres
POSTGRES_PORT=5432
POSTGRES_USER=ticketmaster
POSTGRES_PASSWORD=ticketmaster_secret
POSTGRES_EXTERNAL_PORT=5432

# Service-specific DB names
USER_DB=user_db
EVENT_DB=event_db
BOOKING_DB=booking_db
PAYMENT_DB=payment_db
NOTIFICATION_DB=notification_db

# ── Redis ────────────────────────────────────────────────────────
REDIS_HOST=redis
REDIS_PORT=6379
REDIS_PASSWORD=redis_secret
REDIS_EXTERNAL_PORT=6379

# ── Kafka ────────────────────────────────────────────────────────
KAFKA_BOOTSTRAP_SERVERS=kafka:9092
KAFKA_EXTERNAL_PORT=29092
KAFKA_GROUP_EVENT=event-service-group
KAFKA_GROUP_BOOKING=booking-service-group
KAFKA_GROUP_PAYMENT=payment-service-group
KAFKA_GROUP_NOTIFICATION=notification-service-group
KAFKA_UI_PORT=8090

# ── JWT ──────────────────────────────────────────────────────────
JWT_SECRET=YourVeryLongAndSecureJWTSecretKeyThatIsAtLeast256BitsLong!!
JWT_EXPIRATION_MS=86400000          # 24 hours
JWT_REFRESH_EXPIRATION_MS=604800000 # 7 days

# ── Eureka ───────────────────────────────────────────────────────
EUREKA_USERNAME=eureka
EUREKA_PASSWORD=eureka_secret

# ── Service Ports ────────────────────────────────────────────────
SERVICE_REGISTRY_PORT=8761
API_GATEWAY_PORT=8080
USER_SERVICE_PORT=8081
EVENT_SERVICE_PORT=8082
BOOKING_SERVICE_PORT=8083
PAYMENT_SERVICE_PORT=8084
NOTIFICATION_SERVICE_PORT=8085

# ── Booking Business Rules ───────────────────────────────────────
BOOKING_SEAT_LOCK_TTL_MINUTES=2
BOOKING_MAX_SEATS_PER_ORDER=8
BOOKING_PAYMENT_TIMEOUT_MINUTES=2

# ── Stripe ───────────────────────────────────────────────────────
STRIPE_SECRET_KEY=sk_test_YOUR_STRIPE_SECRET_KEY
STRIPE_WEBHOOK_SECRET=whsec_YOUR_STRIPE_WEBHOOK_SECRET
STRIPE_CURRENCY=usd

# ── Email / SMTP ─────────────────────────────────────────────────
MAIL_HOST=smtp.gmail.com
MAIL_PORT=587
MAIL_USERNAME=your-email@gmail.com
MAIL_PASSWORD=your-app-password
MAIL_FROM_NAME=Ticketmaster
MAIL_FROM_ADDRESS=noreply@ticketmaster.com

# ── CORS ─────────────────────────────────────────────────────────
CORS_ALLOWED_ORIGINS=http://localhost:3000,http://localhost:5173

# ── Monitoring ───────────────────────────────────────────────────
PROMETHEUS_PORT=9090
GRAFANA_PORT=3000
GRAFANA_ADMIN_USER=admin
GRAFANA_ADMIN_PASSWORD=admin_secret

Development Guide

Running services locally (without Docker)

For faster development iteration, run only the infrastructure in Docker and start individual services from your IDE or Maven:

# Start only infrastructure
docker compose up -d postgres redis kafka zookeeper kafka-init service-registry

# Run a specific service (example: user-service)
cd user-service
mvn spring-boot:run

Set the active profile to local to use localhost for all infrastructure connections.

Building the project

# Build all modules
mvn clean package -DskipTests

# Build a specific service
mvn clean package -DskipTests -pl user-service -am

Running tests

# Run all tests
mvn test

# Run tests for a specific service
mvn test -pl booking-service

Code Architecture (per service)

All services follow Clean Architecture / DDD with four layers:

interfaces/       ← REST controllers, DTOs (request/response)
application/      ← Use case handlers, commands, Kafka producers/consumers
domain/           ← Pure business logic, aggregates, domain services
infrastructure/   ← DB entities, JPA repositories, cache, external integrations

Useful Docker commands

# View logs of a specific service
docker logs tm-booking-service -f

# Access PostgreSQL
docker exec -it tm-postgres psql -U ticketmaster -d booking_db

# Access Redis CLI
docker exec -it tm-redis redis-cli -a redis_secret

# Manually re-run Kafka topic setup
docker exec -it tm-kafka bash /kafka-setup.sh

Monitoring

Tool	URL	Credentials
Eureka Dashboard	http://localhost:8761	`eureka` / `eureka_secret`
Kafka UI	http://localhost:8090/kafka-ui	—
Prometheus	http://localhost:9090	—
Grafana	http://localhost:3000	`admin` / `admin_secret`

Grafana is pre-provisioned with Prometheus as a data source (infrastructure/monitoring/grafana/provisioning/). Import JVM and Spring Boot dashboards from Grafana Labs (IDs: 4701, 12900) for instant visibility.

All Spring Boot services expose metrics at /actuator/prometheus for Prometheus scraping.

Project Structure

ticketmaster/
├── pom.xml                          # Parent POM – dependency management for all modules
├── docker-compose.yml               # Full stack deployment
├── docker-compose.override.yml      # Local dev overrides (debug logging, extra ports)
│
├── common-lib/                      # Shared library (DTOs, events, exceptions, security utils)
├── service-registry/                # Netflix Eureka Server
├── api-gateway/                     # Spring Cloud Gateway (JWT, rate-limit, circuit breaker)
│
├── user-service/                    # Authentication & user management → user_db
├── event-service/                   # Events, venues, seat maps → event_db
├── booking-service/                 # Seat reservation & booking → booking_db
├── payment-service/                 # Stripe payment processing → payment_db
├── notification-service/            # Email & SSE notifications → notification_db
│
└── infrastructure/
    ├── postgres/
    │   └── init-databases.sql       # Bootstrap all service databases
    ├── kafka/
    │   └── kafka-setup.sh           # Create all Kafka topics on first start
    ├── nginx/
    │   └── nginx.conf               # Reverse proxy config
    └── monitoring/
        ├── prometheus.yml           # Scrape configs for all services
        └── grafana/
            └── provisioning/        # Auto-provisioned datasources & dashboards

API Endpoints (Summary)

Method	Path	Service	Auth Required
`POST`	`/api/v1/auth/register`	user-service	No
`POST`	`/api/v1/auth/login`	user-service	No
`POST`	`/api/v1/auth/refresh`	user-service	No
`GET`	`/api/v1/users/me`	user-service	Yes
`GET`	`/api/v1/events`	event-service	No
`GET`	`/api/v1/events/{id}`	event-service	No
`POST`	`/api/v1/events`	event-service	Yes (Admin)
`GET`	`/api/v1/venues/{id}`	event-service	No
`GET`	`/api/v1/seats/{eventId}`	event-service	No
`POST`	`/api/v1/bookings`	booking-service	Yes
`GET`	`/api/v1/bookings/{id}`	booking-service	Yes
`DELETE`	`/api/v1/bookings/{id}`	booking-service	Yes
`GET`	`/api/v1/bookings/{id}/stream`	booking-service	Yes (SSE)

Full API documentation is available via Swagger UI at each service:
http://localhost:{port}/swagger-ui.html

Name		Name	Last commit message	Last commit date
Latest commit History 17 Commits
api-gateway		api-gateway
booking-service		booking-service
common-lib		common-lib
event-service		event-service
infrastructure		infrastructure
notification-service		notification-service
payment-service		payment-service
service-registry		service-registry
user-service		user-service
.gitignore		.gitignore
README.md		README.md
docker-compose.override.yml		docker-compose.override.yml
docker-compose.yml		docker-compose.yml
pom.xml		pom.xml

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Latest commit

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🎟️ Ticketmaster – Microservices Backend

📑 Table of Contents

Architecture Overview

Design Patterns Applied

Tech Stack

Core

Spring Cloud Components

Infrastructure

Libraries & Tools

Observability

Services

1. api-gateway (Port 8080)

2. user-service (Port 8081)

3. event-service (Port 8082)

4. booking-service (Port 8083)

5. payment-service (Port 8084)

6. notification-service (Port 8085)

7. service-registry (Port 8761)

8. common-lib

Port Mapping

Kafka Topics

Database Design

Prerequisites

Quick Start

1. Clone the repository

2. Configure environment variables

3. Start all services

4. Verify services are running

5. Run a quick health check

Rebuild after code changes

Stop and clean up

Environment Variables

Development Guide

Running services locally (without Docker)

Building the project

Running tests

Code Architecture (per service)

Useful Docker commands

Monitoring

Project Structure

API Endpoints (Summary)

About

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Languages

1. `api-gateway` (Port 8080)

2. `user-service` (Port 8081)

3. `event-service` (Port 8082)

4. `booking-service` (Port 8083)

5. `payment-service` (Port 8084)

6. `notification-service` (Port 8085)

7. `service-registry` (Port 8761)

8. `common-lib`

Packages