Backup directory environment variable in Docker

[kangaroosinaustria]

I haven't been able to determine why, but my backups are not being written to the specified backup directory.

My install is a docker deployment on Debian 12.

I have set the environment variables in the .env file as such:

# Specify the location of the external data volume
# By default, placed in local directory 'inventree-data'
INVENTREE_EXT_VOLUME=/mnt/data
INVENTREE_BACKUP_DIR=/mnt/backup
INVENTREE_BACKUP_STORAGE=django.core.files.storage.FileSystemStorage

I'm fairly sure I don't need to specify INVENTREE_BACKUP_STORAGE=django.core.files.storage.FileSystemStorage because it's listed in the documentation as the default parameter, but did anyway for troubleshooting.

In the web UI and the docker logs, there are no errors reported with respect to the automatic daily backups.
However, the backups are not being placed in the INVENTREE_BACKUP_DIR.

If I execute a shell in the inventree-worker container using docker exec -it inventree-worker sh, I can run the invoke backup command and it performs the operation with some minor warnings but no issues.

root@inventree:/mnt/backup# docker exec -it inventree-worker sh
/home/inventree # invoke backup
Backing up InvenTree database...
Python version 3.11.9 - /usr/local/bin/python3
/root/.local/lib/python3.11/site-packages/allauth/exceptions.py:9: UserWarning: allauth.exceptions is deprecated, use allauth.core.exceptions
  warnings.warn("allauth.exceptions is deprecated, use allauth.core.exceptions")
Backing Up Database: inventree
 pg_dump --dbname=postgresql://ivdbuser:<redacted_user>@inventree-db:5432/inventree --format=custom
Backup size: 340.2 KiB
Writing file to default-7c522b9326c9-2024-10-16-112104.psql.bin.gz
Backing up InvenTree media files...
Python version 3.11.9 - /usr/local/bin/python3
/root/.local/lib/python3.11/site-packages/allauth/exceptions.py:9: UserWarning: allauth.exceptions is deprecated, use allauth.core.exceptions
  warnings.warn("allauth.exceptions is deprecated, use allauth.core.exceptions")
Backup size: 43.9 MiB
Writing file to 7c522b9326c9-2024-10-16-112108.tar.gz
/home/inventree #

It appears to be writing the backups to a directory that is local only to that docker container (please correct me if I'm misunderstanding - I have a bit of experience with self-hosting software but am still a novice with docker).

/home/inventree # cd /mnt/
/mnt # ls -la
total 12
drwxr-xr-x    1 root     root          4096 Oct 16 02:50 .
drwxr-xr-x    1 root     root          4096 Oct 16 02:50 ..
drwxr-xr-x    2 root     root          4096 Oct 16 03:21 backup
/mnt # cd backup/
/mnt/backup # ls -la
total 90672
drwxr-xr-x    2 root     root          4096 Oct 16 03:21 .
drwxr-xr-x    1 root     root          4096 Oct 16 02:50 ..
-rw-r--r--    1 root     root      46066421 Oct 16 02:55 7c522b9326c9-2024-10-16-105546.tar.gz
-rw-r--r--    1 root     root      46066421 Oct 16 03:21 7c522b9326c9-2024-10-16-112108.tar.gz
-rw-r--r--    1 root     root        348954 Oct 16 02:55 default-7c522b9326c9-2024-10-16-105541.psql.bin.gz
-rw-r--r--    1 root     root        348322 Oct 16 03:21 default-7c522b9326c9-2024-10-16-112104.psql.bin.gz

df -h inside the inventree-worker container returns the following:

/home/inventree # df -h
Filesystem                Size      Used Available Use% Mounted on
overlay                  12.8G      5.3G      6.8G  44% /
tmpfs                    64.0M         0     64.0M   0% /dev
shm                      64.0M    116.0K     63.9M   0% /dev/shm
/dev/mapper/inventree--vg-root
                         12.8G      5.3G      6.8G  44% /etc/resolv.conf
/dev/mapper/inventree--vg-root
                         12.8G      5.3G      6.8G  44% /etc/hostname
/dev/mapper/inventree--vg-root
                         12.8G      5.3G      6.8G  44% /etc/hosts
/dev/sda1                 9.7G    361.8M      8.9G   4% /home/inventree/data
tmpfs                     1.9G         0      1.9G   0% /proc/acpi
tmpfs                    64.0M         0     64.0M   0% /proc/kcore
tmpfs                    64.0M         0     64.0M   0% /proc/keys
tmpfs                    64.0M         0     64.0M   0% /proc/timer_list
tmpfs                     1.9G         0      1.9G   0% /sys/firmware

What have I missed? What do I need to change so that the backups are written to the correct directory?

[kangaroosinaustria]

Okay, I realise now where I've gone wrong. Should have been obvious but years of Windoze conditioning meant I read variable names "EXT_VOLUME" and "BACKUP_DIR" to be interchangeable things, when obviously they are not.
So the docker container can only have one external volume passed to it, and backups must occur within a directory that is within that external volume.

Looks like I'll have to set up rsync.