Move backup to single btrbk instance

flake.nix

@@ -465,7 +465,8 @@
           extraModules = sd-images.packages.${system}.RockPro64v2.modules ++ [
             (networkModule { inherit selfIp; })
             (btrbkModule {
-                instances = builtins.map (item: item // { localMountDir = mountDir; }) backupHosts; 
+                instances = backupHosts;
+                localMountDir = mountDir;
             })
             ({ config, lib, pkgs, ... }: 
             let

modules/btrbk/default.nix

@@ -1,4 +1,5 @@
 { instances ? [ ]
+, localMountDir ? null
 }:
 
 { config, pkgs, ... }:
@@ -55,7 +56,7 @@ let
     };
   };
 
-  backup = primaryIp: remoteMountDir: localMountDir: subvolumes: {
+  backup = instances: {
     backend_remote = "btrfs-progs-sudo";
     ssh_identity = config.sops.secrets.private_key.path;
     ssh_user = "btrbk";
@@ -63,12 +64,12 @@ let
     target_preserve = "2h 2d 10w *m";
     target_preserve_min = "24h";
     transaction_log = "/var/log/btrbk.log";
-    volume = {
-      "ssh://${primaryIp}${remoteMountDir}" = btrbkSecondary {
-        targetDir = "${localMountDir}/@snapshots";
+    volume = builtins.foldl' (acc: { primaryIp, mountDir, name, subvolumes }: acc // {
+      "ssh://${primaryIp}${mountDir}" = btrbkSecondary {
+        targetDir = "${localMountDir}/@snapshots/${name}";
         inherit subvolumes;
       };
-    };
+    }) { } instances;
   };
 in
 {
@@ -84,7 +85,18 @@ in
     btrfs-progs
     (writeShellScriptBin "restore-snapshot" (builtins.readFile ./restore-snapshot))
     (writeShellScriptBin "restore-all-snapshots" (builtins.readFile ./restore-all-snapshots))
-  ];
+  ] ++ (if localMountDir != null then [
+    (writeShellScriptBin
+      "make-backup-subdirectories"
+      (builtins.foldl'
+        (acc: { name, ... }:
+          "${acc}\nmkdir -p ${localMountDir}/@snapshots/${name}"
+        )
+        ""
+        instances
+      )
+    )
+  ] else []);
 
   services.btrbk = {
     sshAccess = [
@@ -94,25 +106,31 @@ in
       }
     ];
     extraPackages = with pkgs; [ gzip ];
-    instances = (builtins.foldl'
-      (acc: { primaryIp ? null, mountDir, localMountDir ? null, subvolumes, name ? "btrbk" }:
-        let
-          selected =
-            if primaryIp == null && localMountDir == null then
-              (primary mountDir subvolumes)
-            else if localMountDir == null then
-              (secondary primaryIp mountDir subvolumes)
-            else
-              (backup primaryIp mountDir localMountDir subvolumes);
-        in
-        acc //
+    instances = if localMountDir == null then
+      (builtins.foldl'
+        (acc: { primaryIp ? null, mountDir, subvolumes, name ? "btrbk" }:
+          let
+            selected =
+              if primaryIp == null then
+                (primary mountDir subvolumes)
+              else
+                (secondary primaryIp mountDir subvolumes);
+          in
+          acc //
+          {
+            ${name} = {
+              onCalendar = "hourly";
+              settings = selected;
+            };
+          })
+        { }
+        instances)
+      else
         {
-          ${name} = {
+          btrbk = {
             onCalendar = "hourly";
-            settings = selected;
+            settings = (backup instances);
           };
-        })
-      { }
-      instances);
+        };
   };
 }