@marcusquinn that plugin was simple 1 to 1 calls directly initiated from the Mattermost ui. For that we leveraged the existing (unfinished) WebRTC integration into Mattermost. Because of this the first version of kwmserver had an api that was compatible to Janus (which was a requirement to the native WebRTC back then).
Currently there is no direct integration of Meet into Mattermost. We simply have too few customers using Mattermost to warrant the invest ourselves, but there was external interest in doing something, for example at https://github.com/Kopano-dev/meet/issues/9.
Wow, what a horrible design for maintenance.
Thanks for finding it.
I'm not interested in editing the DB.
As long as I find where the files are, I can clean those up without removing the messages and references.
Looks like I found just that at /app/data/files/.
A visit via the new File Browser in the Cloudron App Config/Console easily finds the few large attachments.
Another thing I noticed is that MM generates preview and thumbnail images for some reason, which more than doubles the storage requirements for each image uploaded. Some of the generated preview images are larger than the original uploads
thank you for your replies. I found the error in a complete different field. A custom emoji crashed the bulk export. After deleting this I could perform the export as planned and the import to Cloudron worked as described in the documentation. Still thank you for your efforts.