From a5812ff83c0d5e8b5af40cf188929a5a393d77c6 Mon Sep 17 00:00:00 2001
From: Ethan Turkeltaub <ethan.turkeltaub@hey.com>
Date: Wed, 22 Nov 2023 18:05:13 -0500
Subject: [PATCH 1/3] Add `nix.linux-builder.systems` option to set
 corresponding `nix.buildMachines.*.systems` option

---
 modules/nix/linux-builder.nix | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/modules/nix/linux-builder.nix b/modules/nix/linux-builder.nix
index da8d7910..b5ba0191 100644
--- a/modules/nix/linux-builder.nix
+++ b/modules/nix/linux-builder.nix
@@ -57,6 +57,22 @@ in
       '';
     };
 
+    systems = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      example = literalExpression ''
+        [
+          "x86_64-linux"
+          "aarch64-linux"
+        ]
+      '';
+      description = ''
+        This option specifies system types the build machine can execute derivations on.
+
+        This sets the corresponding `nix.buildMachines.*.systems` option.
+      '';
+    };
+
     maxJobs = mkOption {
       type = types.ints.positive;
       default = 1;
@@ -122,7 +138,7 @@ in
       sshKey = "/etc/nix/builder_ed25519";
       system = "${stdenv.hostPlatform.uname.processor}-linux";
       publicHostKey = "c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSUpCV2N4Yi9CbGFxdDFhdU90RStGOFFVV3JVb3RpQzVxQkorVXVFV2RWQ2Igcm9vdEBuaXhvcwo=";
-      inherit (cfg) maxJobs supportedFeatures;
+      inherit (cfg) maxJobs supportedFeatures systems;
     }];
 
     nix.settings.builders-use-substitutes = true;

From 6a3a683d4351e68d746a5aea6953395cedf921bf Mon Sep 17 00:00:00 2001
From: Ethan Turkeltaub <ethan.turkeltaub@hey.com>
Date: Wed, 22 Nov 2023 18:13:01 -0500
Subject: [PATCH 2/3] Use `nix.buildMachines.*.systems` instead of
 `nix.buildMachines.*.system`

---
 modules/nix/linux-builder.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/modules/nix/linux-builder.nix b/modules/nix/linux-builder.nix
index b5ba0191..d09a1cde 100644
--- a/modules/nix/linux-builder.nix
+++ b/modules/nix/linux-builder.nix
@@ -136,9 +136,9 @@ in
       hostName = "linux-builder";
       sshUser = "builder";
       sshKey = "/etc/nix/builder_ed25519";
-      system = "${stdenv.hostPlatform.uname.processor}-linux";
+      systems = [ "${stdenv.hostPlatform.uname.processor}-linux" ] ++ cfg.systems;
       publicHostKey = "c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSUpCV2N4Yi9CbGFxdDFhdU90RStGOFFVV3JVb3RpQzVxQkorVXVFV2RWQ2Igcm9vdEBuaXhvcwo=";
-      inherit (cfg) maxJobs supportedFeatures systems;
+      inherit (cfg) maxJobs supportedFeatures;
     }];
 
     nix.settings.builders-use-substitutes = true;

From 72dd60bfc98c128149d84213b17d1b8a68863055 Mon Sep 17 00:00:00 2001
From: Ethan Turkeltaub <ethan.turkeltaub@hey.com>
Date: Wed, 22 Nov 2023 20:40:03 -0500
Subject: [PATCH 3/3] Add default system to `systems` option

---
 modules/nix/linux-builder.nix | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/modules/nix/linux-builder.nix b/modules/nix/linux-builder.nix
index d09a1cde..2fdcb4a4 100644
--- a/modules/nix/linux-builder.nix
+++ b/modules/nix/linux-builder.nix
@@ -59,14 +59,14 @@ in
 
     systems = mkOption {
       type = types.listOf types.str;
-      default = [ ];
+      default = [ "${stdenv.hostPlatform.uname.processor}-linux" ];
       example = literalExpression ''
         [
           "x86_64-linux"
           "aarch64-linux"
         ]
       '';
-      description = ''
+      description = lib.mdDoc ''
         This option specifies system types the build machine can execute derivations on.
 
         This sets the corresponding `nix.buildMachines.*.systems` option.
@@ -136,9 +136,8 @@ in
       hostName = "linux-builder";
       sshUser = "builder";
       sshKey = "/etc/nix/builder_ed25519";
-      systems = [ "${stdenv.hostPlatform.uname.processor}-linux" ] ++ cfg.systems;
       publicHostKey = "c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSUpCV2N4Yi9CbGFxdDFhdU90RStGOFFVV3JVb3RpQzVxQkorVXVFV2RWQ2Igcm9vdEBuaXhvcwo=";
-      inherit (cfg) maxJobs supportedFeatures;
+      inherit (cfg) maxJobs supportedFeatures systems;
     }];
 
     nix.settings.builders-use-substitutes = true;