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PR_REDIS_REMOVAL.md

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Remove Redis Dependency and Implement Adapter System

🎯 Overview

This PR completely removes Redis as a dependency from the Amber framework and replaces it with a clean, extensible adapter system. The framework now provides memory-based implementations by default and allows users to implement custom adapters for their specific storage and messaging needs.

⚡ Key Changes

✅ Redis Completely Removed

  • Deleted all Redis-specific implementation files
  • Removed conditional compilation flags
  • Eliminated redis_url from configuration
  • No external dependencies required by default

🏗️ New Adapter System

  • Abstract SessionAdapter interface for session storage
  • Abstract PubSubAdapter interface for WebSocket messaging
  • MemorySessionAdapter as default session storage
  • MemoryPubSubAdapter as default pub/sub messaging
  • AdapterFactory for centralized adapter management

📝 Configuration Updates

  • Added adapter key to session configuration
  • Added pubsub configuration section
  • Simplified settings without Redis dependencies

🚨 Breaking Changes

Configuration Format

Before:

session:
  key: "amber.session"
  store: "redis"
  expires: 3600

redis_url: "redis://localhost:6379"

After:

session:
  key: "amber.session"
  store: "signed_cookie"  # For legacy cookie sessions
  adapter: "memory"       # For adapter-based sessions
  expires: 3600

pubsub:
  adapter: "memory"

Removed Classes/Files

  • Amber::Router::Session::RedisStore
  • Amber::WebSockets::Adapters::RedisAdapter
  • Amber::Adapters::RedisSessionAdapter
  • Amber::Adapters::RedisPubSubAdapter
  • All Redis conditional compilation code

Migration Required

Applications using Redis for sessions or pub/sub must:

  1. Implement custom Redis adapters using the new interfaces
  2. Update configuration to use adapter keys
  3. Register custom adapters with AdapterFactory

💡 Benefits

For Framework Maintainers

  • Simplified Codebase: No conditional compilation or external dependencies
  • Easier Testing: Memory adapters make tests faster and more reliable
  • Reduced Complexity: Clean interfaces without implementation coupling

For Application Developers

  • Flexibility: Use any storage/messaging backend (Database, Redis, S3, etc.)
  • No Dependencies: Framework works out-of-the-box without external services
  • Easy Testing: Memory adapters perfect for development and testing
  • Custom Solutions: Implement adapters tailored to specific needs

🔧 Implementation Details

Session Storage

# Abstract interface
abstract class Amber::Adapters::SessionAdapter
  abstract def get(session_id : String) : String?
  abstract def set(session_id : String, value : String) : Nil
  abstract def delete(session_id : String) : Nil
  abstract def destroy(session_id : String) : Nil
  abstract def exists?(session_id : String) : Bool
  # ... additional methods
end

# Memory implementation (built-in)
class Amber::Adapters::MemorySessionAdapter < SessionAdapter
  # Thread-safe implementation with cleanup
end

Pub/Sub Messaging

# Abstract interface  
abstract class Amber::Adapters::PubSubAdapter
  abstract def publish(topic : String, sender_id : String, message : JSON::Any) : Nil
  abstract def subscribe(topic : String, &block : (String, JSON::Any) -> Nil) : Nil
  abstract def unsubscribe(topic : String) : Nil
  # ... additional methods
end

# Memory implementation (built-in)
class Amber::Adapters::MemoryPubSubAdapter < PubSubAdapter
  # Fiber-based async message delivery
end

Adapter Factory

# Register custom adapters
Amber::Adapters::AdapterFactory.register_session_adapter("database") do
  MyDatabaseSessionAdapter.new(MyDB.connection)
end

# Framework creates adapters based on configuration
adapter = AdapterFactory.create_session_adapter("database")

✅ Testing

  • 79 adapter tests pass (0 failures)
  • All existing session and environment tests updated and passing
  • Framework compiles successfully without external dependencies
  • Memory adapters provide full functionality for development and testing

📖 Documentation

  • Updated REDIS_REFACTOR_PLAN.md with complete implementation details
  • Architecture overview and benefits documented
  • Migration guide for existing Redis users
  • Examples for custom adapter implementation

🎯 Future Considerations

Optional Redis Add-on

While Redis is removed from the core framework, the community can create:

  • amber-redis-adapters shard with Redis implementations
  • Drop-in Redis adapters following the new interfaces
  • Easy installation via shard dependencies

Community Adapters

The new system enables community-created adapters for:

  • Database session storage (PostgreSQL, MySQL, SQLite)
  • Message queues (RabbitMQ, Apache Kafka)
  • Cloud services (AWS DynamoDB, Google Cloud Storage)
  • Custom enterprise solutions

🔍 Validation

Run the following to verify the changes:

# Verify compilation
crystal build src/amber.cr --no-codegen

# Run adapter tests
crystal spec spec/amber/adapters/

# Test memory functionality
crystal spec spec/amber/router/session/

This change modernizes Amber's architecture while maintaining the flexibility to use any storage or messaging backend through the clean adapter system.