refactor and modularize btrbk

hosts/yodaNas/btrbk-config.nix

@@ -0,0 +1,54 @@
+{ config, pkgs, ... }:
+let
+  ssd-subvolumes = {
+    "arch.p1st.de" = {};
+    "blogger.privacy1st.de" = {};
+    "changedetection.p1st.de" = {};
+    "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" = {};
+  };
+  hdd-subvolumes = {
+    "cloud.privacy1st.de" = {};
+    # MediaKollektiv: 796 GiB
+    "cloud.media-kollektiv.eu" = {};
+  };
+in
+{
+  yoda.btrbkSnapshots = [
+    {
+      instance = "local-snapshot-ssd";
+      volume = "/jc-data";
+      snapshot_dir = "/snap";
+      subvolume = ssd-subvolumes;
+    }
+    {
+      instance = "local-snapshot-hdd";
+      volume = "/mnt/data/jc-data";
+      snapshot_dir = "/mnt/data/snap2";
+      subvolume = hdd-subvolumes;
+    }
+  ];
+  yoda.btrbkBackups = [
+    {
+      instance = "local-backup-ssd";
+      volume = "/jc-data";
+      snapshot_dir = "/snap";
+      target = "/mnt/backup/snap";
+      subvolume = ssd-subvolumes;
+    }
+    {
+      instance = "local-backup-hdd";
+      volume = "/mnt/data/jc-data";
+      snapshot_dir = "/mnt/data/snap2";
+      target = "/mnt/backup/snap2";
+      subvolume = hdd-subvolumes;
+    }
+  ];
+}

hosts/yodaNas/configuration.nix

@@ -23,6 +23,7 @@
       ../../modules/journalwatch.nix
 
       ../../modules/btrbk
+      ./btrbk-config.nix
       ../../modules/netcup-dns.nix
       ../../modules/de-p1st-monitor.nix
       ../../modules/spin-down.nix

modules/btrbk/backup.nix

@@ -0,0 +1,73 @@
+{ lib, config, options, pkgs, modulesPath, ... }:
+with lib;
+let
+  cfg = config.yoda.btrbkBackups;
+  daily = {
+    preserve-min = "no";
+    preserve = "7d 4w 6m";
+  };
+in
+{
+  options = {
+    yoda.btrbkBackups = mkOption {
+      type = types.listOf types.attrs;
+      default = [];
+      example = [{
+        # Optional.
+        # If this is `true` and `volume` starts with `ssh://`, `lz4` transport compression is enabled.
+        lz4 = true;
+        instance = "local-backup-ssd";
+        volume = "/jc-data";
+        snapshot_dir = "/snap";
+        target = "/mnt/backup/snap";
+        subvolume = {
+          "arch.p1st.de" = {};
+        };
+      }];
+      description = ''
+        List containing attrsets.
+        Each attrset is used to create one btrbk instance.
+      '';
+    };
+  };
+
+  # lib.forEach:
+  #   https://github.com/NixOS/nixpkgs/blob/54f00576aa6139a9d54062d0edc2fb31423f0ffb/lib/lists.nix#L36
+  # lib.attrsets.mergeAttrsList:
+  #   https://github.com/NixOS/nixpkgs/blob/54f00576aa6139a9d54062d0edc2fb31423f0ffb/lib/attrsets.nix#L786
+  config = {
+    services.btrbk.instances =
+      # Merge list of attr sets into one attr set.
+      attrsets.mergeAttrsList (
+        forEach
+        cfg
+        (x:
+          # `services.btrbk.instances` template.
+          {
+            "${x.instance}" = {
+              #onCalendar = null;
+              onCalendar = "00:05";
+              settings = {
+                timestamp_format = "long";
+                stream_compress =  mkIf ((x.lz4 or false) && strings.hasPrefix "ssh://" x.volume) "lz4";
+
+                # Create backups.
+                target_preserve_min = daily.preserve-min;
+                target_preserve = daily.preserve;
+
+                # Don't create or delete snapshots.
+                snapshot_preserve_min = "all";
+                snapshot_create       = "no";
+
+                volume."${x.volume}" = {
+                  snapshot_dir = x.snapshot_dir;
+                  target = x.target;
+                  subvolume = x.subvolume;
+                };
+              };
+            };
+          }
+        )
+      );
+  };
+}

modules/btrbk/default.nix

@@ -11,88 +11,18 @@
 #   #=> ExecStart=/nix/store/53nvbl1c0w14524j7v3fpn9py31yi2hb-btrbk-0.32.6/bin/btrbk -c /etc/btrbk/local-backup.conf run
 
 { config, pkgs, ... }:
-let
-  ssd-subvolumes = {
-    "arch.p1st.de" = {};
-    "blogger.privacy1st.de" = {};
-    "changedetection.p1st.de" = {};
-    "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" = {};
-  };
-  hdd-subvolumes = {
-    "cloud.privacy1st.de" = {};
-    # MediaKollektiv: 796 GiB
-    "cloud.media-kollektiv.eu" = {};
-  };
-  preserve-hourly = "24h 7d 4w 6m";
-  preserve-daily =      "7d 4w 6m";
-in
 {
+  imports = [
+    ./snapshot.nix
+    ./backup.nix
+  ];
+
   services.btrbk = {
+    # Transport compression with `lz4`,
+    # see `./backup.nix`.
     extraPackages = [ pkgs.lz4 ];
     # Lowest scheduling priority.
     niceness = 19;
-    # Set of btrbk instances. The instance named btrbk is the default one.
+    # The `instances` option is set by `./snapshot.nix` and `./backup.nix`.
-    instances = {
-
-      "local-snapshot" = {
-        onCalendar = "hourly";
-        #onCalendar = "*:0/15"; # Every 15min
-
-        settings = {
-          timestamp_format = "long";
-          #stream_compress =  "lz4";
-
-          snapshot_preserve_min = "2d";
-          snapshot_preserve = preserve-hourly;
-
-          volume."/jc-data" = {
-            snapshot_dir = "/snap";
-            subvolume = ssd-subvolumes;
-          };
-          volume."/mnt/data/jc-data" = {
-            snapshot_dir = "/mnt/data/snap2";
-            subvolume = hdd-subvolumes;
-          };
-        };
-      };
-
-      "local-backup" = {
-        # Run daily, 5 minutes after `local-snapshot` 0'o'clock timer.
-        onCalendar = "00:05";
-
-        settings = {
-          timestamp_format = "long";
-          #stream_compress =  "lz4";
-
-          # Create backups.
-          target_preserve_min = "no";
-          target_preserve = preserve-daily;
-
-          # Don't create or delete snapshots.
-          snapshot_preserve_min = "all";
-          snapshot_create       = "no";
-
-          volume."/jc-data" = {
-            snapshot_dir = "/snap";
-            target = "/mnt/backup/snap";
-            subvolume = ssd-subvolumes;
-          };
-          volume."/mnt/data/jc-data" = {
-            snapshot_dir = "/mnt/data/snap2";
-            target = "/mnt/backup/snap2";
-            subvolume = hdd-subvolumes;
-          };
-        };
-      };
-
-    };
   };
 }

modules/btrbk/snapshot.nix

@@ -0,0 +1,62 @@
+{ lib, config, options, pkgs, modulesPath, ... }:
+with lib;
+let
+  cfg = config.yoda.btrbkSnapshots;
+  hourly = {
+    preserve-min = "2d";
+    preserve = "24h 7d 4w 6m";
+  };
+in
+{
+  options = {
+    yoda.btrbkSnapshots = mkOption {
+      type = types.listOf types.attrs;
+      default = [];
+      example = [{
+        instance = "local-snapshot-ssd";
+        volume = "/jc-data";
+        snapshot_dir = "/snap";
+        subvolume = {
+          "arch.p1st.de" = {};
+        };
+      }];
+      description = ''
+        List containing attrsets.
+        Each attrset is used to create one btrbk instance.
+      '';
+    };
+  };
+
+  # lib.forEach:
+  #   https://github.com/NixOS/nixpkgs/blob/54f00576aa6139a9d54062d0edc2fb31423f0ffb/lib/lists.nix#L36
+  # lib.attrsets.mergeAttrsList:
+  #   https://github.com/NixOS/nixpkgs/blob/54f00576aa6139a9d54062d0edc2fb31423f0ffb/lib/attrsets.nix#L786
+  config = {
+    services.btrbk.instances =
+      # Merge list of attr sets into one attr set.
+      attrsets.mergeAttrsList (
+        forEach
+        cfg
+        (x:
+          # `services.btrbk.instances` template.
+          {
+            "${x.instance}" = {
+              #onCalendar = null;
+              onCalendar = "hourly";
+              settings = {
+                timestamp_format = "long";
+
+                snapshot_preserve_min = hourly.preserve-min;
+                snapshot_preserve = hourly.preserve;
+
+                volume."${x.volume}" = {
+                  snapshot_dir = x.snapshot_dir;
+                  subvolume = x.subvolume;
+                };
+              };
+            };
+          }
+        )
+      );
+  };
+}