CLI backup with a specified output directory generates additional files and directories

Hi,

Please find here a report concerning the Yunohost backup system.

Describe the bug

Create a backup from the CLI with a specified output directory generates several files and directories in addition to the .tar archive and the JSON file.

Context

Hardware: VPS
YunoHost version: 4.2.8.1 (no special context or particular tweaks)
OS version: Debian 10.10
I have access to my server through SSH, the webadmin and direct access (via virtual console)

Steps to reproduce

Simply create a backup via the CLI using the --output-directory option :

sudo yunohost backup create --name "maindomain.tld_backup-system-outdir" --description "Manual backup of Yunohost system in a specified directory" --system --output-directory '/backup/system'

Expected behavior

Like what happens when you create a backup without specifing an output directory (thus creating it in /home/yunohost.backup/archives), only the .tar archive and the .info.json file should be created.

Logs

The backup creation output is OK :

Info : Création d’une archive de sauvegarde à partir des fichiers collectés...
Info : L'archive contiendra environ 67.0MiB de données.
Succès ! Sauvegarde terminée
name: maindomain.tld_backup-system-outdir
results: 
  apps: 
  system: 
    conf_ldap: Success
    conf_manually_modified_files: Success
    conf_ynh_certs: Success
    conf_ynh_settings: Success
    data_home: Success
    data_mail: Success
    data_xmpp: Success
size: 70217973

The complete logs can be found here : https://paste.yunohost.org/metekoxiyo.bash

Additional infos

Directory content

You can find below all the files and directories in the output directory after backup creation. It looks like every extra files and directories generated can be found in the .tar archive (which makes sense to me as the archive must contain everything needed by Yunohost) :

backup/system
├── backup.csv
├── conf
│   ├── ldap
│   │   ├── cn=config.master.ldif
│   │   └── dc=yunohost-dc=org.ldif
│   ├── manually_modified_files
│   │   ├── backup
│   │   │   └── system
│   │   │       └── conf
│   │   │           └── manually_modified_files
│   │   ├── etc
│   │   │   └── ssowat
│   │   └── manually_modified_files_list
│   └── ynh
├── maindomain.tld_backup-system-outdir.tar
├── data
│   ├── home
│   └── xmpp
├── hooks
│   └── restore
└── info.json

These 3 JSON files are the same :

/home/yunohost.backup/archives/maindomain.tld_backup-system-outdir.info.json,
/backup/system/info.json,
the info.json inside the archive.

Backup scopes

Also, if the example provided was a system-only backup, the behaviour is the same with a full or apps-only backup. The files and directories generated are :

for an apps-only backup : apps backup.csv maindomain.tld_backup-apps-outdir.tar info.json
for a full backup, a combination of everything : apps backup.csv conf maindomain.tld_backup-full-outdir.tar data hooks info.json

Impact

I found in another, unrelated, issue, that the user there might face the same problem, which would indicate that this issue is not specific to my setup. Quote from https://github.com/YunoHost/issues/issues/1766 :

the command line backup operation outputs multiple files and directories in addition to the .tar archive

Possible resolution

I noticed the .tar archive seems to be the last file generated, so these files and directories are maybe temporary (i don't know how the backup system works), but are not deleted after the operation ?

Thank you for the awesome work on Yunohost and for your time on this issue !

YunoHost / issues