Mattermost Bridge: Consolidating Messages from Multiple External Servers

NOTE: Claude Opus 4 was used for the blog post and the project on github

https://github.com/cln-io/mattermost-bridge

Requirements

We needed a solution to monitor (multiple) external Mattermost instances and forward relevant messages to our primary Mattermost server.

The specific requirements were:

• Monitor specific channels on various external Mattermost servers (run 1 docker per external server, to be seen if I make it multi server compatible)
• Forward messages in real-time to designated channels on our main server
• Preserve message context (author, timestamp, origin server)
• Handle file attachments seamlessly
• Support MFA-enabled accounts
• Maintain professional appearance of forwarded messages
• Minimize manual configuration and maintenance

Screenshots

The left mattermost (the one we want to monitor messages on) has a user posting a message

The console / app log:

Built-in Status Monitoring

As we use mattermost on the fly, I don’t want to check dockerlogs to verify all is going well, so the bridge includes a built-in status channel that provides real-time monitoring of bridge activity and logs. When enabled with STATS_CHANNEL_UPDATES=logs, it creates a dedicated #mattermost-bridge-status channel that continuously updates with:

• Event summaries – Message counts and bridge activity
• Live log feed – Last 30 log lines updated every 10 minutes
• Single message updates – No channel spam, just one continuously updated status message

Solution

The Mattermost Bridge is a TypeScript application that connects to multiple Mattermost instances simultaneously and forwards messages between them.

Key Features

Real-time Message Forwarding

• WebSocket connections for instant message detection
• Automatic forwarding to configured target channels
• No polling delays or missed messages

Complete Context Preservation

• Original author name and profile picture
• Source server identification
• Original timestamps
• All file attachments re-uploaded to target server

Professional Message Presentation

• Forwarded messages appear as formatted attachments
• Clean blue styling distinguishes forwarded content
• Clear metadata showing origin and context
• Maintains readability in busy channels

Robust Architecture

• Automatic reconnection on network failures
• Profile picture caching to reduce API calls
• Configurable rate limiting
• Comprehensive error logging