From 0a948e6148f9add3dfefb288752c9daf870648e9 Mon Sep 17 00:00:00 2001
From: Tom Hubrecht <tom.hubrecht@dgnum.eu>
Date: Mon, 13 May 2024 17:04:49 +0200
Subject: [PATCH] feat: Specialize nixpkgs as a function of the system

---
 hive.nix                      | 77 ++++++++++++++++++++---------------
 machines/ap/configuration.nix |  6 +--
 meta/nixpkgs.nix              | 27 ++++++++----
 meta/nodes.nix                |  7 ++++
 meta/options.nix              | 14 ++++++-
 5 files changed, 86 insertions(+), 45 deletions(-)

diff --git a/hive.nix b/hive.nix
index 85968cd..70f10d1 100644
--- a/hive.nix
+++ b/hive.nix
@@ -17,12 +17,16 @@ let
   };
 
   nixpkgs' = import ./meta/nixpkgs.nix;
+
   # All supported nixpkgs versions, instanciated
-  nixpkgs = lib.mapSingleFuse mkNixpkgs nixpkgs'.supported;
+  nixpkgs = lib.mapSingleFuse (
+    s: lib.mapSingleFuse (mkSystemNixpkgs s) nixpkgs'.versions.supported
+  ) nixpkgs'.systems.supported;
 
   # Get the configured nixos version for the node,
   # defaulting to the one defined in meta/nixpkgs
-  version = node: nodes'.${node}.nixpkgs or nixpkgs'.default;
+  version = node: nodes'.${node}.nixpkgs or nixpkgs'.versions.default;
+  system = node: nodes'.${node}.system or nixpkgs'.systems.default;
 
   # Builds a patched version of nixpkgs, only as the source
   mkNixpkgs' =
@@ -35,55 +39,62 @@ let
       inherit version;
     };
 
-  # Instanciates the required nixpkgs version
-  mkNixpkgs = version: import (mkNixpkgs' version) { };
+  # Instanciate a specialized version of nixpkgs
+  mkSystemNixpkgs =
+    system: version:
+    let
+      args =
+        if system == "nixos" then
+          { }
+        else
+          (import "${sources.liminix}/devices/${system}").system
+          // {
+            overlays = [ (import "${sources.liminix}/overlay.nix") ];
+            config = {
+              allowUnsupportedSystem = true; # mipsel
+              permittedInsecurePackages = [
+                "python-2.7.18.8" # Python < 3 is needed for kernel backports.
+              ];
+            };
+          };
+    in
+    import (mkNixpkgs' version) args;
 
   ###
   # Function to create arguments based on the node
   #
-  mkArgs = node: rec {
-    lib = import sources.nix-lib {
-      inherit (nixpkgs.${version node}) lib;
+  mkArgs =
+    node:
+    let
+      pkgs = nixpkgs.${system node};
+    in
+    rec {
+      lib = import sources.nix-lib {
+        inherit (pkgs.${version node}) lib;
 
-      keysRoot = ./keys;
-    };
+        nixpkgs = pkgs;
 
-    meta = (import ./meta) lib;
-
-    nodeMeta = meta.nodes.${node};
-  };
-
-  apDevice = import "${sources.liminix}/devices/zyxel-nwa50ax";
-  apOverlay = import "${sources.liminix}/overlay.nix";
-
-  apNixpkgs = import (mkNixpkgs' "unstable") (
-    apDevice.system
-    // {
-      overlays = [ apOverlay ];
-      config = {
-        allowUnsupportedSystem = true; # mipsel
-        permittedInsecurePackages = [
-          "python-2.7.18.8" # Python < 3 is needed for kernel backports.
-        ];
+        keysRoot = ./keys;
       };
-    }
-  );
+
+      meta = (import ./meta) lib;
+
+      nodeMeta = meta.nodes.${node};
+    };
 in
 
 {
   registry = {
     liminix = {
-      evalConfig = import "${sources.liminix}/lib/eval-config.nix" { inherit (sources) nixpkgs; };
+      evalConfig = import "${sources.liminix}/lib/eval-config.nix" { nixpkgs = sources.nixos-unstable; };
     };
   };
 
   meta = {
-    nodeNixpkgs = lib.mapSingleFuse (n: nixpkgs.${version n}) nodes // {
-      ap01 = apNixpkgs;
-    };
+    nodeNixpkgs = lib.mapSingleFuse (n: nixpkgs.${system n}.${version n}) nodes;
 
     specialArgs = {
-      inherit nixpkgs sources;
+      inherit sources;
     };
 
     nodeSpecialArgs = lib.mapSingleFuse mkArgs nodes;
diff --git a/machines/ap/configuration.nix b/machines/ap/configuration.nix
index a98a93c..716256d 100644
--- a/machines/ap/configuration.nix
+++ b/machines/ap/configuration.nix
@@ -127,9 +127,9 @@ rec {
   # wlan0 is the 2.4GHz interface.
   services.hostap-1 = mkWifiSta baseParams config.hardware.networkInterfaces.wlan0 secrets-1;
   # wlan1 is the 5GHz interface, e.g. AX capable.
-  services.hostap-2 =
-    mkWifiSta (baseParams // modernParams) config.hardware.networkInterfaces.wlan1
-      secrets-2;
+  services.hostap-2 = mkWifiSta (
+    baseParams // modernParams
+  ) config.hardware.networkInterfaces.wlan1 secrets-2;
 
   defaultProfile.packages = with pkgs; [
     zyxel-bootconfig
diff --git a/meta/nixpkgs.nix b/meta/nixpkgs.nix
index b8c6b43..106f46c 100644
--- a/meta/nixpkgs.nix
+++ b/meta/nixpkgs.nix
@@ -1,10 +1,23 @@
 {
-  # Default version of nixpkgs to use
-  default = "23.11";
+  versions = {
+    # Default version of nixpkgs to use
+    default = "23.11";
 
-  # Supported nixpkgs versions
-  supported = [
-    "unstable"
-    "23.11"
-  ];
+    # Supported nixpkgs versions
+    supported = [
+      "unstable"
+      "23.11"
+    ];
+  };
+
+  systems = {
+    # Default target system
+    default = "nixos";
+
+    # Supported target systems
+    supported = [
+      "nixos"
+      "zyxel-nwa50ax"
+    ];
+  };
 }
diff --git a/meta/nodes.nix b/meta/nodes.nix
index ba634f6..2773af3 100644
--- a/meta/nodes.nix
+++ b/meta/nodes.nix
@@ -86,4 +86,11 @@
     stateVersion = "23.11";
     vm-cluster = "Hyperviseur Luj";
   };
+
+  # Access points definition
+  ap01 = {
+    site = "unknown";
+
+    system = "zyxel-nwa50ax";
+  };
 }
diff --git a/meta/options.nix b/meta/options.nix
index 7bae727..0cc6e9f 100644
--- a/meta/options.nix
+++ b/meta/options.nix
@@ -11,6 +11,7 @@ let
   inherit (lib.types)
     attrs
     attrsOf
+    enum
     ints
     listOf
     nullOr
@@ -35,6 +36,7 @@ let
     };
 
   org = config.organization;
+  nixpkgs = import ./nixpkgs.nix;
 in
 
 {
@@ -124,8 +126,8 @@ in
               };
 
               nixpkgs = mkOption {
-                type = str;
-                inherit (import ./nixpkgs.nix) default;
+                type = enum nixpkgs.versions.supported;
+                inherit (nixpkgs.versions) default;
                 description = ''
                   Version of nixpkgs to use.
                 '';
@@ -167,6 +169,14 @@ in
                 default = null;
                 description = "VM cluster where the VM is located";
               };
+
+              system = mkOption {
+                type = enum nixpkgs.systems.supported;
+                inherit (nixpkgs.systems) default;
+                description = ''
+                  Type of system for the node, will impact how it is evaluated and deployed.
+                '';
+              };
             };
 
             config = {