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Migrating to v15 on Linux

Pluton v15 changes Linux server and AppImage installs to a least-privilege runtime. The installer still needs sudo, but the running service now uses the dedicated non-root pluton system user.

During upgrade, the installer creates the pluton user and group if needed, updates ownership for /var/lib/pluton/ and /etc/pluton/, and installs /usr/bin/pluton-helper for narrow elevated operations. After upgrading, review the permission changes below for any local destinations, scripts, or full-system rescue backup plans you already use.

Local Backup Destinations​

If a backup plan stores data in a local destination, mounted path, external drive, or another directory outside /var/lib/pluton, the pluton user must be able to write there.

On Debian/Ubuntu systems, install ACL support if needed and grant recursive access:

sudo apt update && sudo apt install acl -y
sudo setfacl -R -m u:pluton:rwx,d:u:pluton:rwx /path/to/pluton-backups

Replace /path/to/pluton-backups with the actual backup destination. The d:u:pluton:rwx entry gives new files and directories the same default access.

You can verify access with:

sudo -u pluton test -w /path/to/pluton-backups && echo "pluton can write"

User Scripts​

Normal backup plan scripts now run as the pluton user. If a script does not need root privileges, make sure the pluton user can read and execute it:

sudo chown pluton:pluton /usr/local/libexec/pluton-hooks/pre-backup.sh
sudo chmod 750 /usr/local/libexec/pluton-hooks/pre-backup.sh

If a script does need root privileges, enable root execution for that script in the plan settings and add an explicit sudoers rule for the exact script path:

sudo tee /etc/sudoers.d/pluton-helper-scripts >/dev/null <<'EOF'
pluton ALL=(root) NOPASSWD: /usr/bin/pluton-helper run-script /usr/local/libexec/pluton-hooks/pre-backup-root.sh
EOF
sudo chmod 440 /etc/sudoers.d/pluton-helper-scripts
sudo visudo -c -f /etc/sudoers.d/pluton-helper-scripts

Use one sudoers line per root script. Avoid broad wildcards for hook scripts.

ReaR Rescue Backups​

Pluton PRO full Linux system backups use ReaR. Because ReaR reads block devices, checks layouts, and creates bootable rescue media, it still needs root access through pluton-helper.

If you use full-system rescue backups, add these sudoers rules:

sudo tee /etc/sudoers.d/pluton-helper-rear >/dev/null <<'EOF'
pluton ALL=(root) NOPASSWD: /usr/bin/pluton-helper run-rear mkbackup --config /var/lib/pluton/config/rear-config-*.conf --tmpdir *
pluton ALL=(root) NOPASSWD: /usr/bin/pluton-helper run-rear mkbackuponly --config /var/lib/pluton/config/rear-config-*.conf --tmpdir *
pluton ALL=(root) NOPASSWD: /usr/bin/pluton-helper run-rear checklayout --config /var/lib/pluton/config/rear-config-*.conf --tmpdir *
EOF
sudo chmod 440 /etc/sudoers.d/pluton-helper-rear
sudo visudo -c -f /etc/sudoers.d/pluton-helper-rear

These rules are only needed for ReaR rescue backups. Regular file backups and sync backups do not need the ReaR sudoers entries.

After Migration Checks​

Run these checks after upgrading:

sudo systemctl status pluton
id pluton
ls -ld /var/lib/pluton /etc/pluton
getcap /usr/bin/pluton-helper

Expected results:

  • pluton service is running.
  • id pluton shows the dedicated system user.
  • /var/lib/pluton and /etc/pluton are owned by pluton:pluton.
  • /usr/bin/pluton-helper has cap_chown, cap_dac_override, and cap_fowner capabilities.

If backups fail after migration, check whether the failed plan writes to a local path or runs a script that previously depended on the service running as root.