mattermost/server/platform/services/remotecluster/README.md

Remote Cluster Service

Package remotecluster implements Mattermost's "Secured Connections" feature, which enables communication between different Mattermost clusters. Specifically, this package provides:

Service Management:

• Manages inter-cluster communication via topic-based messages
• Handles connection state (active/inactive) based on cluster leadership
• Maintains concurrent send channels (MaxConcurrentSends = 10) for parallel message processing
• Implements periodic health checks (pings) to monitor remote cluster connectivity

Message Handling:

• Sends messages using a pool of goroutines to handle concurrent sends while preserving message order per remote
• Uses hash-based routing to ensure messages for the same remote ID go to the same channel
• Supports different types of sends: messages, files, and profile images
• Implements topic-based message routing with listener callbacks

Connection Management:

• Handles invitation confirmations between clusters
• Maintains HTTP client connections with proper timeouts and transport settings
• Supports connection state listeners for monitoring remote cluster availability
• Implements ping mechanism to verify remote cluster health

Core Features:

• Topic-based message routing
• File transfer capabilities
• Profile image synchronization
• Invitation system for establishing connections
• Health monitoring via pings
• Concurrent message processing
• Connection state management

This package is designed to be thread-safe and handles leadership changes in clustered environments, only running active operations on the leader node.