Add backup-websites script

Add a bash script that downloads and backs up my static websites from my
server onto my laptop.

nix/home/opdavies/hosts/t480.nix

@@ -28,6 +28,7 @@
   };
 
   home.packages = with pkgs; [
+    backup-websites
     displayselect
     isync
     upload-to-files

nix/pkgs/backup-websites.nix

@@ -0,0 +1,13 @@
+{ lib, pkgs, ... }:
+
+pkgs.writeShellApplication {
+  name = "backup-websites";
+
+  text = ''
+    backup_path="''${HOME}/server-backup"
+
+    mkdir -p "''${backup_path}"
+
+    ${lib.getExe pkgs.rsync} -avzP ssh.oliverdavies.uk:/var/www/vhosts/ "''${backup_path}" --delete-after
+  '';
+}

nix/pkgs/default.nix

@@ -6,6 +6,7 @@ let
   vimPlugins = callPackage ./vim-plugins { inherit callPackage; };
 in
 {
+  backup-websites = callPackage ./backup-websites.nix { };
   build-glove80 = callPackage ./build-glove80.nix { };
   displayselect = callPackage ./displayselect { };
   notes = callPackage ./notes { };