@heptapod For curiosity, is there a similar integration for a federated free/libre protocol (like XMPP or ActivityPub)?
Fundamentally, all it takes is something to receive an HTTP post from GitLab and convert it using the relevant protocol or web API.
I wouldn't be surprised if ejabberd was itself able to act as a gateway to #mattermost servers, either.
@heptapod Ok, thanks for the answer.
Fosstodon is an English speaking Mastodon instance that is open to anyone who is interested in technology; particularly free & open source software.