Mattermost → Rocket.Chat Migration Plugin

A Mattermost server plugin that helps migrate channels from Mattermost to Rocket.Chat. It blocks new messages in migrated channels and redirects users to the corresponding Rocket.Chat channel.

Features

• /migrate <url> — Mark a channel as migrated and point users to the Rocket.Chat URL
• /unmigrate — Remove the migration flag and restore normal channel operation
• Message blocking — Posts in migrated channels are rejected with an ephemeral redirect message
• Channel header update — The channel header is automatically set to show the redirect info
• Configurable — Base URL and redirect message can be set in System Console

Installation

Download and install

1. Download the plugin bundle (right-click → Save Link As to avoid browser auto-extraction):

   Download latest release (.tar.gz)

2. In Mattermost, go to System Console → Plugins → Plugin Management

3. Click Upload Plugin and select the .tar.gz file

4. Click Enable

Tip: If the file picker doesn't show the file, make sure your browser didn't auto-extract it. The file must end in .tar.gz. You can also download it from the terminal:

curl -LO https://github.com/bamsejon/mattermost-plugin-rc-migrate/releases/latest/download/se.bylund.mattermost-plugin-rc-migrate-1.1.0.tar.gz

Build from source

Requires Go 1.21+:

cd mattermost-plugin-rc-migrate
go mod tidy
go mod vendor
make build

This produces dist/se.bylund.mattermost-plugin-rc-migrate-1.1.0.tar.gz.

Configuration

In System Console → Plugins → RC Migrate:

Setting	Description	Default
Rocket.Chat Base URL	Your Rocket.Chat instance URL (informational)	(empty)
Redirect Message	Message shown to users in migrated channels	This channel has moved to Rocket.Chat
API Secret	Shared secret for the REST API (required for external integrations)	(empty — API disabled)

Usage

Migrate a channel

In the channel you want to migrate, run:

/migrate https://rc.example.com/channel/general

This will:

1. Store the migration info in the plugin's KV store
2. Update the channel header with a redirect notice
3. Block all new user messages with an ephemeral redirect

Unmigrate a channel

/unmigrate

This removes the migration flag and clears the channel header.

Permissions

Only channel admins and system admins can run /migrate and /unmigrate.

REST API

The plugin exposes a REST API for external tools to trigger migrations. Requires the API Secret to be configured.

POST /plugins/se.bylund.mattermost-plugin-rc-migrate/api/v1/migrate

curl -X POST https://mattermost.example.com/plugins/se.bylund.mattermost-plugin-rc-migrate/api/v1/migrate \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-api-secret" \
  -d '{"channel_id": "abc123", "url": "https://rc.example.com/channel/general"}'

POST /plugins/se.bylund.mattermost-plugin-rc-migrate/api/v1/unmigrate

curl -X POST https://mattermost.example.com/plugins/se.bylund.mattermost-plugin-rc-migrate/api/v1/unmigrate \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-api-secret" \
  -d '{"channel_id": "abc123"}'

Integration with Rocket.Chat Import App

The Mattermost Import Rocket.Chat app (v2.7.0+) can automatically call this API after importing a channel. To set this up:

1. Configure an API Secret in the Mattermost plugin settings
2. In Rocket.Chat, go to the Mattermost Import app settings
3. Enable Mattermost Redirect and enter the same API secret
4. When you run /importmattermost, the source channel in Mattermost will automatically be redirected

How it works

• Migration state is stored in the Mattermost KV store with key migrated:<channelId>
• The MessageWillBePosted hook intercepts messages and rejects them if the channel is migrated
• System messages and bot posts are not blocked
• An ephemeral message is sent to the user with the Rocket.Chat link

License

MIT