flake: create generator for aarch64 sdcard image

flake.lock

@@ -351,6 +351,42 @@
         "type": "github"
       }
     },
+    "nixlib": {
+      "locked": {
+        "lastModified": 1636849918,
+        "narHash": "sha256-nzUK6dPcTmNVrgTAC1EOybSMsrcx+QrVPyqRdyKLkjA=",
+        "owner": "nix-community",
+        "repo": "nixpkgs.lib",
+        "rev": "28a5b0557f14124608db68d3ee1f77e9329e9dd5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "nixpkgs.lib",
+        "type": "github"
+      }
+    },
+    "nixos-generators": {
+      "inputs": {
+        "nixlib": "nixlib",
+        "nixpkgs": [
+          "nixpkgs-porcupine"
+        ]
+      },
+      "locked": {
+        "lastModified": 1657748715,
+        "narHash": "sha256-WecDwDY/hEcDQYzFnccCNa+5Umht0lfjx/d1qGDy/rQ=",
+        "owner": "nix-community",
+        "repo": "nixos-generators",
+        "rev": "3323b944d99b026aebfd8de439e001409dde067d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "nixos-generators",
+        "type": "github"
+      }
+    },
     "nixos-hardware": {
       "locked": {
         "lastModified": 1654057797,
@@ -610,6 +646,7 @@
         "multitask": "multitask",
         "neovim-nightly": "neovim-nightly",
         "nix-gaming": "nix-gaming",
+        "nixos-generators": "nixos-generators",
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs_2",
         "nixpkgs-porcupine": "nixpkgs-porcupine",

flake.nix

@@ -7,11 +7,13 @@
     neovim-nightly.url = "github:nix-community/neovim-nightly-overlay";
     nixos-hardware.url = "github:NixOS/nixos-hardware";
     agenix.url = "github:ryantm/agenix";
+    nixos-generators.url = "github:nix-community/nixos-generators";
 
     agenix.inputs.nixpkgs.follows = "nixpkgs";
     home-manager.inputs.nixpkgs.follows = "nixpkgs";
     home-manager-porcupine.inputs.nixpkgs.follows = "nixpkgs-porcupine";
     neovim-nightly.inputs.nixpkgs.follows = "nixpkgs";
+    nixos-generators.inputs.nixpkgs.follows = "nixpkgs-porcupine";
 
     nix-gaming.url = "github:fufexan/nix-gaming";
     powercord-overlay.url = "github:LavaDesu/powercord-overlay";
@@ -61,7 +63,7 @@
     zelk = { url = "github:schnensch0/zelk"; flake = false; };
   };
 
-  outputs = { self, agenix, nixpkgs, nixpkgs-porcupine, ... } @ inputs:
+  outputs = { self, agenix, nixos-generators, nixpkgs, nixpkgs-porcupine, ... } @ inputs:
     let
       overlays = (import ./overlays)
         ++ [inputs.powercord-overlay.overlay]
@@ -71,13 +73,13 @@
 
       mkSystem =
         if !(self ? rev) then throw "Dirty git tree detected." else
-        nixpkgs: name: arch: enableGUI: nixpkgs.lib.nixosSystem {
+        nixpkgs: name: arch: enableGUI: extraModules: nixpkgs.lib.nixosSystem {
           system = arch;
           modules = [
             { nixpkgs.overlays = overlays; }
             agenix.nixosModules.age
             (./hosts + "/${name}")
-          ];
+          ] ++ extraModules;
           specialArgs = {
             inherit inputs enableGUI;
             modules = import ./modules { lib = nixpkgs.lib; };
@@ -85,10 +87,10 @@
         };
     in
     {
-      nixosConfigurations."blossom" = mkSystem nixpkgs "blossom" "x86_64-linux" true;
+      nixosConfigurations."blossom" = mkSystem nixpkgs "blossom" "x86_64-linux" true [];
 
-      nixosConfigurations."caramel" = mkSystem nixpkgs-porcupine "caramel" "aarch64-linux" false;
+      nixosConfigurations."caramel" = mkSystem nixpkgs-porcupine "caramel" "aarch64-linux" false [];
-      nixosConfigurations."sugarcane" = mkSystem nixpkgs-porcupine "sugarcane" "x86_64-linux" false;
+      nixosConfigurations."sugarcane" = mkSystem nixpkgs-porcupine "sugarcane" "x86_64-linux" false [];
 
       packages."x86_64-linux" =
         let
@@ -104,12 +106,36 @@
       packages."aarch64-linux" =
         let
           pkgs = import nixpkgs-porcupine {
-            inherit overlays;
+            overlays = overlays ++ [
+              # See https://github.com/NixOS/nixpkgs/issues/126755#issuecomment-869149243
+            ];
             system = "aarch64-linux";
           };
+
+          caramel-sys = mkSystem nixpkgs-porcupine "caramel" "aarch64-linux" false [{
+            nixpkgs.overlays = [
+              (self: super: {
+                makeModulesClosure = x: super.makeModulesClosure (x // { allowMissing = true; });
+              })
+            ];
+          }];
         in
         {
           inherit (pkgs) nixUnstable;
+
+          caramel-iso2 = caramel-sys.config.system.build.sdImage;
+          caramel-iso = nixos-generators.nixosGenerate {
+            inherit pkgs;
+            format = "sd-aarch64";
+            modules = [
+              agenix.nixosModules.age
+              ./hosts/caramel
+            ];
+            specialArgs = {
+              inherit inputs;
+              modules = import ./modules { lib = nixpkgs-porcupine.lib; };
+            };
+          };
         };
 
       # TODO: currently broken

hosts/caramel/default.nix

@@ -1,4 +1,4 @@
-{ config, inputs, modules, overlays, pkgs, ... }: {
+{ config, inputs, modules, modulesPath, overlays, pkgs, ... }: {
   networking.hostName = "caramel";
   system.stateVersion = "21.11";
   time.timeZone = "Asia/Phnom_Penh";
@@ -12,6 +12,7 @@
   };
   imports =
     (with modules.system; [
+      "${builtins.toString modulesPath}/installer/sd-card/sd-image-aarch64.nix"
       inputs.home-manager-porcupine.nixosModule
 
       base
@@ -23,15 +24,16 @@
 
       ./filesystem.nix
       ./kernel.nix
+      ./image.nix
       ./networking.nix
       ./packages.nix
 
       ../../users/hana
     ]) ++
     (with modules.services; [
-      nginx
+#       nginx
-      postgres
+#       postgres
-      synapse
+#       synapse
       tmptsync
       unbound
       vaultwarden

hosts/caramel/filesystem.nix

@@ -1,4 +1,4 @@
-{ config, ... }:
+{ config, lib, ... }:
 let
   bind = src: {
     depends = [ "/persist" ];
@@ -9,16 +9,31 @@ let
   };
 in {
   fileSystems = {
-    "/" = {
+    "/" = lib.mkForce {
       device = "rootfs";
       fsType = "tmpfs";
-      options = [ "defaults" "size=2G" "mode=755" ];
+      options = [ "defaults" "size=1G" "mode=755" ];
     };
 
-    "/nix" = {
+    # "/nix" = {
+    #   device = "overlayfs";
+    #   fsType = "overlay";
+    #   options = [
+    #     "lowerdir=/mnt/image/nix"
+    #     "upperdir=/persist/nix-overlay"
+    #     "workdir=/persist/.overlaytmp"
+    #   ];
+    #   noCheck = true;
+    #   depends = [ "/mnt/image" "/persist" ];
+    # };
+
+    "/nix" = (bind "/mnt/image/nix") // { depends = [ "/mnt/image" ]; };
+
+    "/mnt/image" = {
       device = "/dev/disk/by-label/NIXOS_SD";
       fsType = "ext4";
       options = [ "defaults" "noatime" ];
+      neededForBoot = true;
     };
 
     "/persist" = {
@@ -31,6 +46,6 @@ in {
     "/var/persist" = bind "/persist";
     "/var/lib/acme" = bind "/persist/acme";
     "/var/log/journal" = bind "/persist/journal";
-    "/boot" = (bind "/nix/persist/boot") // { depends = [ "/nix" ]; };
+    "/boot" = (bind "/mnt/image/boot") // { depends = [ "/mnt/image" ]; };
   };
 }

hosts/caramel/image.nix

@@ -0,0 +1,29 @@
+{ config, lib, pkgs, ... }: {
+  sdImage.expandOnBoot = false;
+  boot.postBootCommands = ''
+    # On the first boot do some maintenance tasks
+    if [ -f /mnt/image/nix-path-registration ]; then
+      set -euo pipefail
+      set -x
+      # Figure out device names for the boot device and root filesystem.
+      rootPart=$(${pkgs.util-linux}/bin/findmnt -n -o SOURCE /mnt/image)
+      bootDevice=$(lsblk -npo PKNAME $rootPart)
+      partNum=$(lsblk -npo MAJ:MIN $rootPart | ${pkgs.gawk}/bin/awk -F: '{print $2}')
+
+      # Resize the root partition and the filesystem to fit the disk
+      echo ",+," | sfdisk -N$partNum --no-reread $bootDevice
+      ${pkgs.parted}/bin/partprobe
+      ${pkgs.e2fsprogs}/bin/resize2fs $rootPart
+
+      # Register the contents of the initial Nix store
+      ${config.nix.package.out}/bin/nix-store --load-db < /mnt/image/nix-path-registration
+
+      # nixos-rebuild also requires a "system" profile and an /etc/NIXOS tag.
+      touch /etc/NIXOS
+      ${config.nix.package.out}/bin/nix-env -p /nix/var/nix/profiles/system --set /run/current-system
+
+      # Prevents this from running on later boots.
+      rm -f /mnt/image/nix-path-registration
+    fi
+  '';
+}

hosts/caramel/kernel.nix

@@ -1,11 +1,15 @@
-{ config, inputs, pkgs, ... }: {
+{ config, inputs, lib, pkgs, ... }: {
   imports = [
     inputs.nixos-hardware.nixosModules.raspberry-pi-4
   ];
   hardware.raspberry-pi."4".fkms-3d.enable = true;
 
-  boot.kernel.sysctl = {
+  boot = {
-    "kernel.core_pattern" = "|/bin/false";
+    initrd.kernelModules = [ "overlay" ];
-    "kernel.sysrq" = 1;
+    supportedFilesystems = lib.mkForce [ "btrfs" "vfat" ];
+    kernel.sysctl = {
+      "kernel.core_pattern" = "|/bin/false";
+      "kernel.sysrq" = 1;
+    };
   };
 }