goplt/docs/content/stories/epic5/5.2-event-bus.md

Story 5.2: Event Bus System

Metadata

• Story ID: 5.2
• Title: Event Bus System
• Epic: 5 - Infrastructure Adapters
• Status: Pending
• Priority: High
• Estimated Time: 6-8 hours
• Dependencies: 1.1

Goal

Implement a complete event bus system supporting both in-process (for development/testing) and Kafka (for production) with publish/subscribe capabilities.

Description

This story implements an event bus that allows modules to publish and subscribe to events. It supports both in-process channels for development and Kafka for production, with a clean interface that makes the implementation swappable.

Deliverables

1. Event Bus Interface (pkg/eventbus/eventbus.go)

• EventBus interface with:
  • Publish(ctx context.Context, topic string, event Event) error
  • Subscribe(topic string, handler EventHandler) error
  • Unsubscribe(topic string) error
• Event and EventHandler types

2. In-Process Bus (internal/infra/bus/inprocess_bus.go)

• Channel-based in-process bus
• Used for testing and development
• Thread-safe implementation

3. Kafka Bus (internal/infra/bus/kafka_bus.go)

• Kafka producer for publishing
• Consumer groups for subscribing
• Error handling and retries
• Connection management

4. Core Events

• Define core platform events:
  • platform.user.created
  • platform.user.updated
  • platform.role.assigned
  • platform.permission.granted

5. Configuration

• Kafka config in config/default.yaml
• Bus selection (in-process vs Kafka)

6. DI Integration

• Provider function for EventBus
• Register in DI container
• Switchable via config

Acceptance Criteria

• Event bus interface is defined
• In-process bus works for development
• Kafka bus works for production
• Events can be published and subscribed
• Bus is swappable via config
• Error handling works correctly
• Core events are defined

Files to Create/Modify

• pkg/eventbus/eventbus.go - Event bus interface
• internal/infra/bus/inprocess_bus.go - In-process implementation
• internal/infra/bus/kafka_bus.go - Kafka implementation
• internal/di/providers.go - Add event bus provider
• config/default.yaml - Add Kafka config