Can't get previewgenerator to work in openmediavault setting


New to the forum, and really rather new to hosing my own Linux server but I’m getting the hang of it step by step. I now have a openmediavault running on top of a Armbian/Debian Stretch distro on my mini server (arm). Nextcloud is running in docker as per the guide that Techno Dad Life has on youtube Nextcloud in OMV docker

Everything with Nextcloud is running smooth but now when I want Nextcloud to act as my familys photo storage/management I really need the preview generator to make it work. I somehow can’t get it to start with the different commands I found in all the guides. The app itself installs through the Nextcloud web interface, but when I want to run the commands I get into trouble.

So if someone could give me a quick step by step guide to run preview generator in my setting with OMV running Nextcloud in a docker container I’d be really thankful. I believe I could use the scheduled jobs tab (cron) to run the initial preview generating and then later the scheduled jobs but I only get long and, for me, incomprehensible error messages. But that could be because of my lack of understanding where the preview generator wants to run - in or outside of the Nextcloud container.

Thanks in advance for any help you can give me

NCP has new tool that might help, the command it uses is

sudo -u www-data php /var/www/nextcloud/occ preview:generate-all

Check all the code on Github

You would have to go into container with

docker exec -it [NCcontainername] bash

and cd to the nextcloud directory before using the occ tool without sudo, because you’ll be root already, plain su should do.

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I have tried something similar before but then as now stranded on the missing www-data user. (No passwd entry for user ‘www-data’ if trying to su the command and sudo: unknown user: www-data, sudo: unable to initialize policy plugin if trying to sudo the command).

I know that Nextcloud as default uses www-data but I’ve never had any www-data user configured in my system and thought I didn’t need to create one, but I could have misunderstood that. My users are added in www-data group at least. Do I need to create a new user www-data in OMV for just this purpose?

Also /var/www/ has no nextcloud folder in my container. When configuring the docker container I put my data in a folder outside the container on my server so occ is located in /sharedfolders/AppData/Nextcloud/www/nextcloud/

Hi there,

Did you get to make it work ? I’m in the same situation : /

Same here.

It’s a pity there isnt even any explanation of the config options of this nc-previews in the config reference.
when you run ncp-config it says:
Enter the configuration for nc-previews


No word about what should be set here in the reference: Configuration-Reference | NextCloudPi Documentation

I mean, how should you know?! Should I enter /var/www/nextcloud into the PATH1 or what?

nc-preview explained