From 6cee9ab06c1ce14af014f6f56dd2f991984d6d71 Mon Sep 17 00:00:00 2001
From: mc-fucker <dev@mc-fucker.cool>
Date: Sun, 29 Jan 2023 08:46:21 +0100
Subject: [PATCH] made borg use btrfs snapshot

---
 modules/borg.nix | 39 +++++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/modules/borg.nix b/modules/borg.nix
index 2aff7a7..84be93d 100644
--- a/modules/borg.nix
+++ b/modules/borg.nix
@@ -1,20 +1,23 @@
-{ config, ... }:
+{ config, pkgs, ... }:
+let
+  backuppath = "/backup/snapshot";
+in
 {
   services.borgbackup.jobs.default = {
     paths = [
-      "/etc"
-      "/home"
-      "/root"
-      "/var"
+      "${backuppath}/etc"
+      "${backuppath}/home"
+      "${backuppath}/root"
+      "${backuppath}/var"
     ];
     exclude = [
-      "*/.cache"
-      "/home/*/build"
-      "/var/log"
-      "/var/lib/nextcloud/data/appdata_ocnc33s4dl6i/preview"
-      "/var/lib/postgresql/*/"
-      "/var/lib/containers"
-      "/var/lib/rancher/k3s/agent/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots"
+      "${backuppath}*/.cache"
+      "${backuppath}/home/*/build"
+      "${backuppath}/var/log"
+      "${backuppath}/var/lib/nextcloud/data/appdata_ocnc33s4dl6i/preview"
+      "${backuppath}/var/lib/postgresql/*/"
+      "${backuppath}/var/lib/containers"
+      "${backuppath}/var/lib/rancher/k3s/agent/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots"
     ];
     repo = "borg@haus.mc-fucker.cool:/mnt/sdf1/borg/${config.networking.hostName}";
     compression = "zstd";
@@ -22,6 +25,18 @@
     environment.BORG_RSH = "ssh -o 'StrictHostKeyChecking=no' -i /root/.ssh/id_borg";
     extraCreateArgs = "--verbose --stats";
     startAt = "03:00";
+    preHook = ''if [[ -d ${backuppath} ]]; then
+        btrfs subvolume delete ${backuppath}
+      fi
+      btrfs subvolume snapshot / ${backuppath}''; #create snapshot for consistent filesystem
+    postCreate = "btrfs subvolume delete ${backuppath}"; #delete snapshot again
+  };
+
+  systemd.services.borgbackup-job-default = {
+    path = [ pkgs.btrfs-progs ];
+    serviceConfig = {
+      ReadWritePaths = [ "/backup" ];
+    };
   };
 }