Richdocuments / Collabora seems to ignore preview setting for PDF


in the last days I’ve tried to investigate a problem which seems to be connected to the richdocuments app and the PDF preview function of Nextcloud:

I’ve found many .tmp files on the server under /tmp/systemd-private--apache2.service/tmp/ that were never cleaned up by the system. Looking into those files I saw, that these are actually big .pdf files with the extension .tmp. As these were never deleted I’ve looked into the logs and there shows up an error “message”:“Failed to convert file to preview” when executing /index.php/core/preview?fileId=12345&x=32&y=32. This seems to be connected to a timeout when getting the file to generate the preview.

I haven’t been successful in finding the source of the timeout, but I saw something else that I would like to report here and ask if someone could give me some more information:

I have installed the richdocuments and richdocumentscode app to be able to use Collabora Online. This works without problems but seems to have a side effect on the preview generation for PDF files.
My config.php contains only these preview providers:

'enabledPreviewProviders' =>
  array (
    0 => 'OC\\Preview\\Image',
    1 => 'OC\\Preview\\MP3',
    2 => 'OC\\Preview\\TXT',
    3 => 'OC\\Preview\\MarkDown',

so no PDF preview should be generated (i think so). As in the logs i found the error described before I’ve looked into richdocuments/lib/Preview/ and found out that there is also a preview provider for pdf files that gets executed when the user browses his files. If the generation of the preview fails, the .tmp file seems to remain on the disc under /tmp/.

Is this a expected behavior when Collabora is installed? Or is richdocuments ignoring erroneously the configuration in config.php?

At the moment I modified the Office.php in richdocuments/lib/Preview/ to block the generation of previews by richdocuments to prevent a full disk on the server…


a new search in the issues of richdocuments took me to this: Previews generated when not turned on · Issue #1335 · nextcloud/richdocuments · GitHub
So the problem seems already known.