What's an easy way to access a directory of a docker volume with Nextcloud which is running in another docker container?

Question

I hope this is the right place to ask this question.

My problems is as follows: I have a Ubuntu Server 22.04.2 with docker running on my home server. On one docker container I'm running Nextcloud and on another container I'm running paperless-ngx. Now I would like to access my scanned files from paperless via nextcloud.

• So far I tried using Proftpd to add my Paperless-ngx archive directory via FTP as external storage to nextcloud. I think that this didn't work, because the docker volume isn't saved on my profile but instead in the system(?) files. So I couldn't access the directory with my profile login and also trying to login in as a root user didn't work either.

• Next, I tried to create a soft/symbolic link with ln -s /<path to directory> /<path to directory>. The link was working but I also couldnt create the external storage on nextcloud with Proftpd. I'm not entirely sure why it didn't work, but I think it's because the linked directory has the same root settings (which I was not able to change) as the original directory thus using FTP was not possible.

• Lastly, I tried using a soft link from my paperless directory directly to my nextcloud directory. I could see the directory in the terminal but it didn't show up, when I tried to access it in nextcloud.

I'm pretty new to using Ubuntu Servers and Docker containers so I probably made some silly decisions along the way. Could I have done something different to get it to work? Or are my "workarounds" not feasible at all? If so: Is there an easy solution to get this to work?

Answer 1

The easiest way to do this (for homelab use) is by using Docker bind mounts for persistent storage.

The official Nextcloud image even has a section describing this (under Persistent Data).

An example of the command needed to run with persistent volumes for the config and data would be:

$ docker run -d \
    -p 8080:80 \
    -v /path/to/appdata:/var/www/html/config \
    -v /path/to/data:/var/www/html/data \
    nextcloud

Here, /path/to/appdata and /path/to/data need to be replaced with the actual full path of the folder where you want this persistent storage to be.

You could then map the folder /path/to/data into another container using the same method, allowing this folder to be directly shared between multiple containers and the host filesystem itself.