config.toml

[slack.hacklabto]
Token="${SLACK_HACKLABTO_TOKEN}" # bot user
RemoteNickFormat="{NICK}@{BRIDGE}.{PROTOCOL} "

[gitter.hacklabto]
Token="${GITTER_HACKLABTO_TOKEN}" # bot user: hacklabto twitter account
RemoteNickFormat="{NICK}@{PROTOCOL}: "

## HACKLAB

[[gateway]]
name="lobby"
enable=true
  [[gateway.inout]]
  account="slack.hacklabto"
  channel="public-lobby"
  [[gateway.inout]]
  account="gitter.hacklabto"
  channel="hacklabto/lobby"

console.log

/non_encrypted/repos/matterbridge-heroku (edgi ✔) ᐅ http GET https://api.gitter.im/v1/rooms Authorization:"Bearer $TOKEN"
HTTP/1.1 200 OK
Access-Control-Expose-Headers: X-RateLimit-Limit,X-RateLimit-Remaining,X-RateLimit-Reset
Connection: keep-alive
Content-Encoding: gzip
Content-Length: 328
Content-Type: application/json; charset=utf-8
Date: Sat, 04 Nov 2017 23:23:11 GMT
ETag: W/"1cf-9SgZ5VAPWxXqnAlEY6pr+Lk0X1E"
Server: nginx
Vary: Origin
X-RateLimit-Limit: 100
X-RateLimit-Remaining: 99
X-RateLimit-Reset: 1509837851427
X-Server-ID: webapp-03
X-Upstream: 127.0.0.1:5025

[
    {
        "avatarUrl": "https://avatars-02.gitter.im/group/iv/4/59fd5fb5d73408ce4f7d15a9", 
        "githubType": "REPO_CHANNEL", 
        "groupId": "59fd5fb5d73408ce4f7d15a9", 
        "id": "59fd6299d73408ce4f7d15e8", 
        "lastAccessTime": "2017-11-04T22:55:33.000Z", 
        "lurk": false, 
        "mentions": 0, 
        "name": "lobby/lobby", 
        "noindex": false, 
        "oneToOne": false, 
        "public": true, 
        "roomMember": true, 
        "security": "PUBLIC", 
        "tags": [], 
        "topic": "testing2", 
        "unreadItems": 4, 
        "uri": "hacklabto/lobby", 
        "url": "/hacklabto/lobby", 
        "userCount": 2
    }
]

matterbridge.log

2017-11-04T22:55:33.348673+00:00 app[worker.1]: time="2017-11-04T22:55:33Z" level=debug msg="Sending message from patcon on slack.hacklabto to gateway" module=slack 
2017-11-04T22:55:33.348783+00:00 app[worker.1]: time="2017-11-04T22:55:33Z" level=debug msg="Message is config.Message{Text:"testing 2", Channel:"public-lobby", Username:"patcon", UserID:"U7G938MCJ", Avatar:"https://secure.gravatar.com/avatar/7e945991d1d70075cff59331d72ef4d8.jpg?s=48&d=https%3A%2F%2Fa.slack-edge.com%2F66f9%2Fimg%2Favatars%2Fava_0017-48.png", Account:"slack.hacklabto", Event:"", Protocol:"", Gateway:"", Timestamp:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}, ID:"slack 1509836132.000061", Extra:map[string][]interface {}{}}" module=slack 
2017-11-04T22:55:33.348977+00:00 app[worker.1]: time="2017-11-04T22:55:33Z" level=debug msg="Sending config.Message{Text:"testing 2", Channel:"public-lobby", Username:"patcon", UserID:"U7G938MCJ", Avatar:"https://secure.gravatar.com/avatar/7e945991d1d70075cff59331d72ef4d8.jpg?s=48&d=https%3A%2F%2Fa.slack-edge.com%2F66f9%2Fimg%2Favatars%2Fava_0017-48.png", Account:"slack.hacklabto", Event:"", Protocol:"", Gateway:"lobby", Timestamp:time.Time{wall:0xbe77af3954cbe396, ext:22463256076, loc:(*time.Location)(0x13f00a0)}, ID:"slack 1509836132.000061", Extra:map[string][]interface {}{}} from slack.hacklabto (public-lobby) to gitter.hacklabto (hacklabto/lobby)" 
2017-11-04T22:55:33.349031+00:00 app[worker.1]: time="2017-11-04T22:55:33Z" level=debug msg="Receiving config.Message{Text:"testing 2", Channel:"hacklabto/lobby", Username:"patcon@slack: ", UserID:"U7G938MCJ", Avatar:"https://secure.gravatar.com/avatar/7e945991d1d70075cff59331d72ef4d8.jpg?s=48&d=https%3A%2F%2Fa.slack-edge.com%2F66f9%2Fimg%2Favatars%2Fava_0017-48.png", Account:"slack.hacklabto", Event:"", Protocol:"", Gateway:"lobby", Timestamp:time.Time{wall:0xbe77af3954cbe396, ext:22463256076, loc:(*time.Location)(0x13f00a0)}, ID:"", Extra:map[string][]interface {}{}}" module=gitter 
2017-11-04T22:55:37.165690+00:00 app[worker.1]: time="2017-11-04T22:55:37Z" level=debug msg="Sending message from patcon on gitter.hacklabto to gateway" module=gitter 
2017-11-04T22:55:37.165982+00:00 app[worker.1]: time="2017-11-04T22:55:37Z" level=debug msg="Message is config.Message{Text:"testing 3", Channel:"lobby/lobby", Username:"patcon", UserID:"54eb674315522ed4b3dc5ec1", Avatar:"https://avatars0.githubusercontent.com/u/305339?v=4&s=60", Account:"gitter.hacklabto", Event:"", Protocol:"", Gateway:"", Timestamp:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}, ID:"59fe4569e44c43700aba5130", Extra:map[string][]interface {}(nil)}" module=gitter