add btrbk

hosts/yodaNas/configuration.nix

@@ -57,6 +57,7 @@ in
       #../../modules/waydroid.nix
       #../../modules/ntfs.nix
       #../../modules/veracrypt.nix
+      ../../modules/btrbk
     ];
 
   networking.hostName = "yodaNas";

hosts/yodaTab/configuration.nix

@@ -55,6 +55,7 @@ in
       #../../modules/waydroid.nix
       ../../modules/ntfs.nix
       #../../modules/veracrypt.nix
+      #../../modules/btrbk
     ];
 
   networking.hostName = "yodaTab";

hosts/yodaTux/configuration.nix

@@ -55,6 +55,7 @@ in
       #../../modules/waydroid.nix
       ../../modules/ntfs.nix
       #../../modules/veracrypt.nix
+      #../../modules/btrbk
     ];
 
   networking.hostName = "yodaTux";

hosts/yodaYoga/configuration.nix

@@ -57,6 +57,7 @@ in
       #../../modules/waydroid.nix
       #../../modules/ntfs.nix
       #../../modules/veracrypt.nix
+      #../../modules/btrbk
     ];
 
   networking.hostName = "yodaYoga";

modules/btrbk/default.nix

@@ -0,0 +1,108 @@
+{ config, pkgs, ... }:
+
+{
+  # For each instance, a service and timer will be created:
+  #   systemctl list-unit-files | grep btrbk
+  #   #=> btrbk-<instance-name>.service
+  #   #=> btrbk-<instance-name>.timer
+  #
+  # If onCalendar is set to null, one can manually execute btrbk with
+  #   sudo systemctl start btrbk-<instance-name>.service
+
+  # Print generated systemd unit file
+  #   cat "$(systemctl show -P FragmentPath btrbk-<instance-name>.service)"
+
+  # TODO: Maybe the following is not necessary if using hd-idle anyways (!)
+  # TODO: Mount/Unmount backup drive
+  #   Example1:
+  #     - https://github.com/oxalica/nixos-config/blob/1b18628afda9cecca0bc8c348b91e3ae6ab56905/nixos/invar/btrbk.nix#L55
+  #     - https://github.com/oxalica/nixos-config/blob/1b18628afda9cecca0bc8c348b91e3ae6ab56905/nixos/invar/btrbk.nix#L64
+  #   Example2:
+  #     - https://github.com/emmanuelrosa/erosanix/blob/master/modules/btrbk.nix#L35-L42C7
+
+  # Spin down (unmounted/inactive) HDD disk.
+  # Inspired by https://www.reddit.com/r/NixOS/comments/751i5t/comment/do3f3l7/
+  #
+#  environment.systemPackages = with pkgs; [
+#    hd-idle
+#  ];
+#  systemd.services.hd-idle = {
+#    description = "Spin down inactive HDD";
+#    wantedBy = [ "multi-user.target" ];
+#    serviceConfig = {
+#      Type = "simple";
+#      # Options:
+#      # -a <disk>: Select disk for subsequent parameters.
+#      # -i 180: Spin down after 2 minutes (180 seconds) of inactivity.
+#      ExecStart = "${pkgs.hd-idle}/bin/hd-idle -a /dev/disk/by-id/XXX-XXX-XXX -i 180"; # TODO make disk id configurable
+#    };
+#  };
+
+  services.btrbk = {
+    extraPackages = [ pkgs.lz4 ];
+    # Lowest scheduling priority.
+    niceness = 19;
+    # Set of btrbk instances. The instance named btrbk is the default one.
+    instances = {
+
+#      # This is the configuration equivalent to
+#      # README.md section "Testing on Local Host".
+#      "testing-on-local-host" = {
+#        # The timer is disabled. The service has to be invoked manually.
+#        onCalendar = null;
+#        #onCalendar = "hourly";
+#        #onCalendar = "*:0/15"; # Every 15min
+#        # Configuration options for btrbk. Nested attrsets translate to subsections.
+#        settings = {
+#          timestamp_format = "long";
+#          stream_compress = "lz4";
+#
+#          snapshot_preserve_min = "2d";
+#          snapshot_preserve = "24h 7d 4w 6m";
+#
+#          target_preserve_min = "no";
+#          target_preserve = "7d 4w 6m";
+#
+#          volume."/mnt/top-level" = {
+#            snapshot_dir = "@snap";
+#            target = "/mnt/usb-top-level/@snap";
+#            subvolume = "@foo";
+#          };
+#        };
+#      };
+
+      "local-snapshots" = {
+        onCalendar = "hourly";
+        #onCalendar = "*:0/15"; # Every 15min
+
+        settings = {
+          timestamp_format = "long";
+          stream_compress = "lz4";
+
+          snapshot_preserve_min = "2d";
+          snapshot_preserve = "24h 7d 4w 6m";
+
+          volume."/mnt/data/data" = {
+            snapshot_dir = "/mnt/data/snap";
+            subvolume = {
+              "arch.p1st.de" = {};
+              "blogger.privacy1st.de" = {};
+              "changedetection.p1st.de" = {};
+              "cloud.media-kollektiv.eu" = {};
+              "cloud.privacy1st.de" = {};
+              "git.privacy1st.de" = {};
+              #"mastodon-toot-follower.privacy1st.de" = {};
+              "money.p1st.de" = {};
+              "music.privacy1st.de" = {};
+              #"paste.p1st.de" = {};
+              "proxy" = {};
+              "recipe.privacy1st.de" = {};
+              "traggo.privacy1st.de" = {};
+            };
+          };
+        };
+      };
+
+    };
+  };
+}