Was looking for an automated opml export for my main user, after tweaking/updating I recreated all my containers and volumes - I lost everything (no great loss).
So I found I can execute the following docker command:
docker exec -it -u 1000 tt-rss_backups_1 php8 /var/www/html/tt-rss/update.php --opml-export USER:/backups/<filename.opml
Where user is one of the users on your system, and the -u 1000 is any ID/GID you’ve set for execution. Mine is the default.
One addition though, is that I’ve extended the docker-compose file as docker-compose-override.yml where I set a local path for the backups volume for the backup container.
eg docker-compose-override.sh is:
version: "3.3"
services:
backups:
volumes:
- <your local path for backups>:/backups
And you create the containers with:
docker-compose -f docker-compose.yml -f docker-compose-override.yml up -d
Hope someone finds that useful. Otherwise all the automated backups go into a mounted volume you don’t have access to, now mine are pushed to a folder that is then backed up by other tools (and I have other backups there)