[Unit]
Description=Backrest Daemon
After=network.target
# /var/lib/backrest, which also holds the restic cache, can be a volume of
# its own: without it backrest would start over with an empty config. Does
# nothing while it is part of the root filesystem.
RequiresMountsFor=/var/lib/backrest

[Service]
Type=simple
ExecStart=/usr/bin/backrest -restic-cmd /usr/bin/restic -data-dir /var/lib/backrest/ -config-file /var/lib/backrest/config.json
Restart=on-failure
StandardOutput=append:/var/log/backrest/backrest.log
StandardError=append:/var/log/backrest/backrest.log
# restic keeps its cache in $XDG_CACHE_HOME/restic. To move it elsewhere,
# add a drop-in with "systemctl edit backrest":
#   [Unit]
#   RequiresMountsFor=/var/cache/backup/restic
#   [Service]
#   Environment=RESTIC_CACHE_DIR=/var/cache/backup/restic
Environment=XDG_CACHE_HOME=/var/lib/backrest/

[Install]
WantedBy=multi-user.target