borg-backup: init repo if doesn't exist

services/borg-backup.nix

@@ -54,6 +54,7 @@ in {
       environment.BORG_RSH = "ssh -i /root/borgbackup/ssh_key";
       extraCreateArgs = "--stats --list";
       extraPruneArgs = "--stats --list";
+      doInit = true;
       compression = "auto,zstd";
       startAt = "daily";
       prune.keep = {

services/nextcloud.nix

@@ -75,8 +75,12 @@ in
       nextcloudHome = config.services.nextcloud.home;
     in lib.mkIf cfg.enable  {
       paths = [ nextcloudHome ];
+      exclude = [
         # borg can fail if *.part files disappear during backup
-      exclude = [ "${nextcloudHome}/data/*/uploads" ];
+        "re:^${nextcloudHome}/data/[^/]+/uploads"
+        # image previews can take up a lot of space
+        "re:^${nextcloudHome}/data/appdata_[^/]+/preview"
+      ];
     };
   };
 }