Mattermost, an open source self-hosted alternative to Slack has been set up at PIK. This service is closely integrated with GitLab and thus requires you to log in via your GitLab (PIK) credentials.
https://mattermost.pik-potsdam.de
The user guide can be found here: https://docs.mattermost.com/guides/user.html
Mattermost can be used to receive GitLab project notifications. The (per-project) setup is described here: https://docs.gitlab.com/ee/user/project/integrations/mattermost.html
Mattermost client applications for Android and Apple are also available (see https://mattermost.com/download/#mobile)
If you encounter any bugs or other unexpected behaviour, or have any specific usage questions not covered in the user guide please file a ticket with it-support@pik-potsdam.de
