Ability to set SQLite backup location

[a-was]

Hi, thanks for the great work on Vaultwarden! I'm just getting started with it, and while setting up my backup scripts, I ran into a small issue that could be addressed

It would be useful to have an option to configure a custom directory for SQLite backups, for example, through a new BACKUP_FOLDER environment variable

Currently, the /vaultwarden backup command saves the backup in the data directory. This makes it a bit difficult to use in automated backup scripts, as the command output is not particularly convenient to work with programmatically

For example, my current backup script looks like this:

VW_DATA_PATH="/some/vaultwarden/data/path"

BACKUP_FILE=$(
    docker compose exec -it vaultwarden \
        /vaultwarden backup \
        | grep -oP "Backup to '.*/\K[^']+"
)

mv "$VW_DATA_PATH/$BACKUP_FILE" "backup/db.sqlite3"
# backup...
rm -f "backup/db.sqlite3"

The script needs to parse the command output to determine the backup filename and then move the generated file out of the data directory before passing it to the backup process

The command currently prints a message like Backup to 'data/db_20261013_112233.sqlite3' was successful, which is not really convenient for automation, as scripts need to extract the filename from the output

With a configurable backup location, the script could be simplified considerably. For example, if we could set:

services:
  vaultwarden:
    ...
    environment:
      BACKUP_FOLDER: /backup
    volumes:
      - ./some/data/:/data/
      - ./some/backup/:/backup/

and the /vaultwarden backup command could write the backup directly to that directory. The script could then access the exported database without having to parse the command output or move the file from the data directory

This would also allow the script to assume that the backup directory is empty before each run and operate on a single file in that directory, without needing to determine the generated filename

As a side note, it might also be worth considering whether the backup command's output could be made more automation-friendly, for example, by providing the generated filename in a more easily parseable format.

Backup command output:

vaultwarden/src/main.rs

Lines 188 to 190 in 6489552

	match db::backup_sqlite() {
	Ok(f) => {
	println!("Backup to '{f}' was successful");

Filename generation:

vaultwarden/src/db/mod.rs

Lines 415 to 416 in 6489552

	let backup_file = db_path
	.join(format!("db_{}.sqlite3", chrono::Utc::now().format("%Y%m%d_%H%M%S")))

This would make it easier to integrate Vaultwarden's built-in backup functionality with external backup tools and automated backup workflows