From bb76f3914548a5501353515e91f738987ea058c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Sun, 19 May 2024 13:49:36 +0200
Subject: [PATCH] iso: default to zstd compression

For most users of nixos-generate zstd will be the better choice as
it will build and boot images much faster. Often users have to rebuild
images a couple of times before they are happy with the result.
NixOS might be better of with xz as it saves download and storage cost
for images.
---
 formats/install-iso.nix | 3 +++
 formats/iso.nix         | 5 ++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/formats/install-iso.nix b/formats/install-iso.nix
index f047167..e7fbd05 100644
--- a/formats/install-iso.nix
+++ b/formats/install-iso.nix
@@ -12,6 +12,9 @@
   systemd.services.wpa_supplicant.wantedBy = lib.mkForce ["multi-user.target"];
   systemd.services.sshd.wantedBy = lib.mkForce ["multi-user.target"];
 
+  # Much faster than xz
+  isoImage.squashfsCompression = lib.mkDefault "zstd";
+
   formatAttr = "isoImage";
   fileExtension = ".iso";
 }
diff --git a/formats/iso.nix b/formats/iso.nix
index 4531e7a..1b1a232 100644
--- a/formats/iso.nix
+++ b/formats/iso.nix
@@ -1,5 +1,5 @@
 {
-  config,
+  lib,
   modulesPath,
   ...
 }: {
@@ -13,6 +13,9 @@
   # USB booting
   isoImage.makeUsbBootable = true;
 
+  # Much faster than xz
+  isoImage.squashfsCompression = lib.mkDefault "zstd";
+
   formatAttr = "isoImage";
   fileExtension = ".iso";
 }