Web_BLS_ProjectConsole/openspec/specs/redis-connection/design.md

Redis Connection Capability Design

Context

This design document describes the technical implementation of the Redis connection capability for the BLS Project Console, which manages the connection between the system and the Redis server for reading logs and sending commands.

Goals / Non-Goals

Goals

• Establish and manage connection to Redis server
• Provide configuration options for Redis connection
• Implement automatic reconnection mechanism
• Handle connection errors gracefully
• Monitor and report connection status

Non-Goals

• Redis server administration
• Redis cluster management
• Advanced Redis features (e.g., pub/sub, streams) beyond basic queue operations

Decisions

Decision: Redis Client Library

• What: Use the official redis npm package
• Why: It's the official Redis client for Node.js, well-maintained, and supports all Redis commands
• Alternatives considered:
  • ioredis: More features but more complex
  • node-redis: Older, less maintained

Decision: Connection Configuration

• What: Use environment variables for Redis connection configuration
• Why: Environment variables are a standard way to configure services in containerized environments, and they allow easy configuration without code changes
• Alternatives considered:
  • Configuration files: Less flexible for containerized environments
  • Hardcoded values: Not suitable for production use

Decision: Reconnection Strategy

• What: Use exponential backoff for reconnection attempts
• Why: Exponential backoff prevents overwhelming the Redis server with reconnection attempts, while still ensuring timely reconnection
• Alternatives considered:
  • Fixed interval reconnection: Less efficient, could overwhelm the server
  • No reconnection: Not suitable for production use

Architecture

Redis Connection Architecture

Redis Connection Manager
├── Redis Client
├── Connection Monitor
├── Reconnection Handler
└── Configuration Manager

Implementation Details

Redis Client Initialization

1. Server reads Redis configuration from environment variables
2. Server creates a Redis client instance with the configuration
3. Server attaches event listeners for connection events (connect, error, end, reconnecting)
4. Server attempts to connect to Redis

Configuration Parameters

Parameter	Default Value	Environment Variable	Description
host	localhost	REDIS_HOST	Redis server hostname
port	6379	REDIS_PORT	Redis server port
password	null	REDIS_PASSWORD	Redis server password
db	0	REDIS_DB	Redis database index
connectTimeout	10000	REDIS_CONNECT_TIMEOUT	Connection timeout in milliseconds
maxRetriesPerRequest	3	REDIS_MAX_RETRIES	Maximum retries per request
reconnectStrategy	exponential	REDIS_RECONNECT_STRATEGY	Reconnection strategy (exponential, fixed)
reconnectInterval	1000	REDIS_RECONNECT_INTERVAL	Base reconnection interval in milliseconds
maxReconnectInterval	30000	REDIS_MAX_RECONNECT_INTERVAL	Maximum reconnection interval in milliseconds

Reconnection Implementation

• Use the built-in reconnection feature of the redis package
• Configure exponential backoff with:
  • Initial delay: 1 second
  • Maximum delay: 30 seconds
  • Factor: 1.5
• Log each reconnection attempt with timestamp and delay

Error Handling

• Connection errors: Log the error, update connection status, and attempt to reconnect
• Command errors: Log the error, update the command status, and notify the user
• Timeout errors: Log the error, update connection status, and attempt to reconnect

Connection Monitoring

• Track connection status (connecting, connected, disconnected, error)
• Log status changes with timestamps
• Expose connection status via API endpoint
• Update UI with connection status changes via Server-Sent Events (SSE)

Risks / Trade-offs

Risk: Redis Server Unavailability

• Risk: If the Redis server is unavailable for an extended period, the system won't be able to read logs or send commands
• Mitigation: Implement proper error handling and reconnection logic, and notify users of the issue

Risk: Misconfiguration of Redis Connection

• Risk: Incorrect Redis configuration could lead to connection failures
• Mitigation: Validate configuration on startup, log configuration values (excluding passwords), and provide clear error messages

Risk: Performance Impact of Reconnection Attempts

• Risk: Frequent reconnection attempts could impact system performance
• Mitigation: Use exponential backoff to reduce the frequency of reconnection attempts, and limit the maximum reconnection delay

Migration Plan

No migration is required as this is a new feature.

Open Questions

• What is the expected Redis server availability?
• Should we implement connection pooling for better performance?
• Should we support Redis Sentinel or Cluster for high availability?