3 files changed, 118 insertions, 0 deletions
diff --git a/sys/btrfs/default.nix b/sys/btrfs/default.nix
new file mode 100644
index 0000000..ee76537
--- /dev/null
+++ b/sys/btrfs/default.nix
@@ -0,0 +1,6 @@
+{
+  imports = [
+    ./mounts.nix
+    ./snapper.nix
+  ];
+}
diff --git a/sys/btrfs/mounts.nix b/sys/btrfs/mounts.nix
new file mode 100644
index 0000000..133f08f
--- /dev/null
+++ b/sys/btrfs/mounts.nix
@@ -0,0 +1,39 @@
+{ lib, config, pkgs, ... }:
+with lib; let
+  cfg = config.local.btrfs;
+in
+{
+  options.local.btrfs = {
+    mounts = mkOption {
+      default = { };
+
+      type = with lib.types; attrsOf (submodule {
+        options = {
+          ssd = mkOption {
+            type = bool;
+          };
+
+          device = mkOption {
+            type = str;
+          };
+
+          subvol = mkOption {
+            type = str;
+          };
+        };
+      });
+    };
+  };
+
+  config = mkIf (cfg.mounts != { }) {
+    fileSystems =
+      let
+        btrfsMount = { device, subvol, ssd }: {
+          inherit device;
+          fsType = "btrfs";
+          options = [ "noatime" "compress=zstd" "subvol=${subvol}" ] ++ optional ssd "ssd";
+        };
+      in
+      mapAttrs (_: btrfsMount) cfg.mounts;
+  };
+}
diff --git a/sys/btrfs/snapper.nix b/sys/btrfs/snapper.nix
new file mode 100644
index 0000000..27d2779
--- /dev/null
+++ b/sys/btrfs/snapper.nix
@@ -0,0 +1,73 @@
+{ config, lib, pkgs, ... }:
+with lib; let
+  cfg = config.local.btrfs;
+in
+{
+  options.local.btrfs = {
+    snapper = mkOption {
+      type = with lib.types; attrsOf str;
+      default = { };
+    };
+  };
+
+  config = mkIf (cfg.snapper != { }) {
+    environment.systemPackages = [ pkgs.local.btclone ];
+
+    services.snapper.configs =
+      let
+        snapperConfig = _: subvolume: {
+          SUBVOLUME = subvolume;
+
+          # btrfs qgroup for space aware cleanup algorithms
+          QGROUP = "";
+
+          # fraction of the filesystems space the snapshots may use
+          SPACE_LIMIT = "0.5";
+
+          # fraction of the filesystems space that should be free
+          FREE_LIMIT = "0.2";
+
+          # users and groups allowed to work with config
+          ALLOW_USERS = [ ];
+          ALLOW_GROUPS = [ ];
+
+          # sync users and groups from ALLOW_USERS and ALLOW_GROUPS to .snapshots
+          # directory
+          SYNC_ACL = "no";
+
+          # start comparing pre- and post-snapshot in background after creating
+          # post-snapshot
+          BACKGROUND_COMPARISON = "yes";
+
+          # run daily number cleanup
+          NUMBER_CLEANUP = "yes";
+
+          # limit for number cleanup
+          NUMBER_MIN_AGE = "1800";
+          NUMBER_LIMIT = "100";
+          NUMBER_LIMIT_IMPORTANT = "10";
+
+          # create hourly snapshots
+          TIMELINE_CREATE = true;
+
+          # cleanup hourly snapshots after some time
+          TIMELINE_CLEANUP = true;
+
+          # limits for timeline cleanup
+          TIMELINE_MIN_AGE = "1800";
+          TIMELINE_LIMIT_HOURLY = "24";
+          TIMELINE_LIMIT_DAILY = "7";
+          TIMELINE_LIMIT_WEEKLY = "4";
+          TIMELINE_LIMIT_MONTHLY = "12";
+          TIMELINE_LIMIT_YEARLY = "10";
+
+          # cleanup empty pre-post-pairs
+          EMPTY_PRE_POST_CLEANUP = "yes";
+
+          # limits for empty pre-post-pair cleanup
+          EMPTY_PRE_POST_MIN_AGE = "1800";
+        };
+      in
+      mapAttrs snapperConfig cfg.snapper;
+  };
+}