From 90b5fc0f886cdc74eb731e946a0cc4d84631bafa Mon Sep 17 00:00:00 2001
From: rnhmjoj <rnhmjoj@inventati.org>
Date: Tue, 11 Jul 2023 12:15:05 +0200
Subject: [PATCH] jobs: prune backups every 7 days

---
 jobs.nix | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/jobs.nix b/jobs.nix
index 2c712dd..665aa55 100644
--- a/jobs.nix
+++ b/jobs.nix
@@ -55,16 +55,26 @@ with lib;
     '';
   };
 
+  systemd.mounts = lib.singleton
+    {
+      description = "backup NFS volume";
+      after = [ "network-online.target" ];
+
+      what    = "192.168.1.3:/maxwell";
+      where   = "/mnt/backup";
+      type    = "nfs";
+      options = "nolock";
+    };
 
   systemd.services.backup =
   let
-    saved = ''
+    saved = pkgs.writeText "backup-saved" ''
       /etc/lvm
       /var/lib
       /home
     '';
 
-    excluded = ''
+    excluded = pkgs.writeText "backup-excluded" ''
       /var/lib/systemd
       /var/lib/udisks2
       /var/lib/postgresql
@@ -74,7 +84,8 @@ with lib;
 
   in {
     description = "system backup";
-    after       = [ "network-online.target" ];
+    after       = [ "network-online.target" "mnt-backup.mount" ];
+    bindsTo     = [ "mnt-backup.mount" ];
     startAt     = "*-*-* 03:00";  # every day at 3:00
     onFailure   = [ "notify-failed@backup.service" ];
 
@@ -88,29 +99,24 @@ with lib;
     path = with pkgs; [ bup git nfs-utils sudo gzip postgresql ];
 
     script = ''
-      set -e
-
       # mount repository
       mkdir -p "$BUP_DIR"
-      mount.nfs -o nolock 192.168.1.3:/maxwell "$BUP_DIR"
 
       # init backup
       ! test -e $BUP_DIR/bupindex && bup init
 
       # build indices and save
-      saved=${pkgs.writeText "backup-saved" saved}
-      excluded=${pkgs.writeText "backup-excluded" excluded}
       while read -r dir; do
         name=$(basename "$dir")
 
         echo indexing $name...
-        bup index "$dir" --exclude-from="$excluded"
+        bup index "$dir" --exclude-from="${excluded}"
         echo done
 
         echo saving $name...
         bup save -n "$name" "$dir"
         echo done
-      done < "$saved"
+      done < "${saved}"
 
       # postgresql backup
       dir=/tmp/postgresql
@@ -125,9 +131,12 @@ with lib;
       bup save -n postgresql "$dir" --strip-path=/tmp
       echo done
 
-      echo pruning...
-      bup prune-older --keep-all-for 6m --keep-monthlies-for 2y --unsafe
-      echo done
+      # prune backups every week
+      if test $(( $(date +%s) / 86400 % 7 )) -eq 0; then
+        echo pruning...
+        bup prune-older --keep-all-for 6m --keep-monthlies-for 2y --unsafe
+        echo done
+      fi
     '';
   };