1 files changed, 111 insertions, 0 deletions
diff --git a/sys/fs/btrfs.nix b/sys/fs/btrfs.nix
new file mode 100644
index 0000000..87c9fca
--- /dev/null
+++ b/sys/fs/btrfs.nix
@@ -0,0 +1,111 @@
+{ lib, config, pkgs, ... }:
+with lib; let
+  cfg = config.local;
+in {
+  options.local = with lib.types; {
+    snapperSubvols = mkOption {
+      type = attrsOf str;
+      default = {};
+    };
+
+    fs.btrfs = mkOption {
+      default = [];
+
+      type = attrsOf (submodule {
+        options = {
+          device = mkOption {
+            type = str;
+          };
+
+          subvol = mkOption {
+            type = str;
+          };
+
+          ssd = mkOption {
+            type = bool;
+          };
+
+          snapper = mkOption {
+            type = nullOr str;
+            default = null;
+          };
+        };
+      });
+    };
+  };
+
+  config = {
+    environment.systemPackages = optional (cfg.snapperSubvols != {}) pkgs.local.btclone;
+
+    fileSystems = let
+      inherit (cfg) fs;
+      btrfs = { device, subvol, ssd, ... }: {
+        inherit device;
+        fsType = "btrfs";
+        options = [ "noatime" "compress=zstd" "subvol=${subvol}" ] ++ optional ssd "ssd";
+      };
+    in mapAttrs (_: btrfs) cfg.fs.btrfs;
+
+    local.snapperSubvols = let
+      snapperEntry = path: opts: { name = opts.snapper; value = path; };
+      validEntry = _: opts: opts.snapper != null;
+    in mapAttrs' snapperEntry (filterAttrs validEntry cfg.fs.btrfs);
+
+    services.snapper.configs = let
+      snapperConfig = _: subvolume: {
+        inherit subvolume;
+
+        extraConfig = ''
+          # 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="yes"
+
+          # cleanup hourly snapshots after some time
+          TIMELINE_CLEANUP="yes"
+
+          # 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.snapperSubvols;
+  };
+}