Add timed backup

role/backup.nix

@@ -0,0 +1,66 @@
+{
+ systemdMount,
+ borgArchiveFolder,
+ keepWithin? "14d",
+ keepWeekly? "4",
+ keepMonthly? "6",
+ keepYearly? "-1",
+}:
+
+let pkgs = import<nixpkgs>{};
+in
+{
+
+  systemd =  {
+    services.backup = {
+      description = "Backup of all user data and system configuration with BorgBackup";
+      serviceConfig.Type = "oneshot";
+      path = with pkgs; [ bash borgbackup ];
+      script = ''
+        #!/usr/bin/env bash
+        set -euo pipefail
+        IFS=$'\n\t'
+        
+        systemctl start ${systemdMount}
+
+        export BORG_REPO=${borgArchiveFolder} \
+               BORG_BASE_DIR=${borgArchiveFolder}/borg-base-dir
+        
+        echo "Backup started at `date`"
+        borg create --exclude /var/backup \
+                    --exclude /var/tmp \
+                    --exclude /var/cache \
+                    $BORG_REPO::{hostname}-{now} \
+                    /etc \
+                    /home \
+                    /root \
+                    /var
+        
+        sync
+        echo "Backup finished at `date`"
+        
+        echo "Backup prune started at `date`"
+        borg prune --prefix '{hostname}-' \
+                   --keep-within  ${keepWithin} \
+                   --keep-weekly  ${keepWeekly} \
+                   --keep-monthly ${keepMonthly} \
+                   --keep-yearly  ${keepYearly}
+        sync
+        echo "Backup prune finished at `date`"
+
+        systemctl stop ${systemdMount}
+      '';
+    };
+
+    timers.backup = {
+      description = "Backup Schedule";
+
+      timerConfig = {
+        OnCalendar = "13:37";
+        Persistent = "true";
+      };
+
+      wantedBy = [ "timers.target" ];
+    };
+  };
+}