Make installer image more independent

installer.nix

@@ -0,0 +1,81 @@
+{ pkgs, lib, modulesPath, config, ... }:
+
+with lib;
+
+let
+  auto-installer = pkgs.writers.writeBash "auto-installer" ''
+      set -o errexit
+      set -o nounset
+      set -o pipefail
+
+      set -x
+
+      if [[ "$(cat /proc/cmdline)" =~ nixos\.install=([^ ]+) ]]; then
+        INSTALL="''${BASH_REMATCH[1]}"
+      else
+        echo "No install derivation found" >&2
+        exit 1
+      fi
+
+      ${pkgs.retry}/bin/retry \
+        --times 10 \
+        --delay 15 \
+        -- ${pkgs.nix}/bin/nix-store \
+          --realize \
+          --add-root /tmp/installer \
+          "$INSTALL"
+
+    exec /tmp/installer
+  '';
+
+in
+{
+  imports = [
+    "${modulesPath}/installer/netboot/netboot-minimal.nix"
+
+    ./shared/network.nix
+    ./shared/cache.nix
+    ./shared/users.nix
+  ];
+
+  _module.args = {
+    name = "installer";
+  };
+
+  networking.useDHCP = mkForce true;
+
+  services.getty.autologinUser = lib.mkForce "root";
+
+  systemd.services."auto-install" = {
+    description = "Automated NixOS installer";
+
+    wants = [ "network-online.target" ];
+    after = [ "network-online.target" ];
+
+    conflicts = [ "getty@tty1.service" ];
+
+    wantedBy = [ "multi-user.target" ];
+
+    path = with pkgs; [ bash nix ];
+
+    unitConfig = {
+      AssertKernelCommandLine = "nixos.install";
+
+      FailureAction = "force-reboot";
+    };
+
+    serviceConfig = {
+      Type = "oneshot";
+
+      ExecStart = auto-installer;
+
+      StandardInput = "none";
+      StandardOutput = "journal+console";
+      StandardError = "journal+console";
+    };
+  };
+
+  # Expose the installer script
+  system.build.installer = installer;
+}
+

installer/default.nix

@@ -1,86 +0,0 @@
-{ pkgs, lib, modulesPath, config, target, ... }:
-
-with lib;
-
-let
-  installer = pkgs.callPackage ./installer.nix { inherit target; };
-
-  auto-installer =
-    let
-      # This removes the direct dependency from the installer to the target image.
-      # The install script is realized later during runtime using the cache.
-      # To make this work, the cache must provide the real installer script.
-      installer-path = builtins.unsafeDiscardStringContext (toString installer);
-
-    in
-    pkgs.writers.writeBash "auto-installer" ''
-        set -o errexit
-        set -o nounset
-        set -o pipefail
-
-        set -x
-
-        ${pkgs.retry}/bin/retry \
-          --times 10 \
-          --delay 15 \
-          -- ${pkgs.nix}/bin/nix-store \
-            --realize \
-            --add-root /tmp/installer \
-            "${installer-path}"
-
-      /tmp/installer
-
-      reboot
-    '';
-
-in
-{
-  imports = [
-    "${modulesPath}/installer/netboot/netboot-minimal.nix"
-
-    ../shared/users.nix
-    ../shared/network.nix
-    ../shared/cache.nix
-  ];
-
-  _module.args = {
-    name = "installer";
-  };
-
-  networking.useDHCP = mkForce true;
-
-  services.getty.autologinUser = lib.mkForce "root";
-
-  systemd.services."auto-install" = {
-    description = "Automated NixOS installer";
-
-    wants = [ "network-online.target" ];
-    after = [ "network-online.target" ];
-
-    conflicts = [ "getty@tty1.service" ];
-
-    wantedBy = [ "multi-user.target" ];
-
-    path = with pkgs; [ bash nix ];
-
-    unitConfig = {
-      FailureAction = "force-reboot";
-    };
-
-    serviceConfig = {
-      Type = "oneshot";
-
-      ExecStart = auto-installer;
-
-      StandardInput = "none";
-      StandardOutput = "journal+console";
-      StandardError = "journal+console";
-    };
-  };
-
-  # Expose the installer script
-  system.build.installer = installer;
-
-  system.stateVersion = config.system.nixos.release;
-}
-

installer/installer.nix

@@ -1,19 +0,0 @@
-{ writers, target, ... }:
-
-writers.writeBash "installer" ''
-  set -o errexit
-  set -o nounset
-  set -o pipefail
-
-  set -x
-
-  "${target.config.system.build.diskoScript}"
-
-  "${target.config.system.build.nixos-install}/bin/nixos-install" \
-    --root /mnt \
-    --system "${target.config.system.build.toplevel}" \
-    --no-channel-copy \
-    --no-root-password \
-    --verbose
-''
-

machines/nfs/dhcp.nix

@@ -63,28 +63,6 @@
               pool = "10.32.44.100 - 10.32.44.200";
             }
           ];
-
-          option-data = [
-            {
-              name = "routers";
-              data = "10.32.44.1";
-            }
-
-            {
-              name = "domain-name-servers";
-              data = "10.0.0.53";
-            }
-
-            {
-              name = "domain-name";
-              data = config.networking.domain;
-            }
-
-            {
-              name = "domain-search";
-              data = config.networking.domain;
-            }
-          ];
         }
       ];
 

machines/nfs/netinstaller.nix

@@ -4,15 +4,31 @@ with lib;
 
 let
   installer = pkgs.nixos [
-    ../../installer
-
-    {
-      _module.args = {
-        target = nodes."client";
-      };
-    }
+    ../../installer.nix
   ];
 
+  installer-script =
+    let
+      target = nodes."client".config.system.build;
+
+    in
+    pkgs.writers.writeBash "installer" ''
+      set -o errexit
+      set -o nounset
+      set -o pipefail
+    
+      set -x
+    
+      "${target.diskoScript}"
+    
+      "${target.nixos-install}/bin/nixos-install" \
+        --root /mnt \
+        --system "${target.toplevel}" \
+        --no-channel-copy \
+        --no-root-password \
+        --verbose
+    '';
+
   ipxe-script = pkgs.writeText "boot-local.ipxe" ''
     #!ipxe
 
@@ -26,7 +42,7 @@ let
     kernel --name kernel http://''${next-server:ipv4}/bzImage || goto err
     initrd --name initrd http://''${next-server:ipv4}/initrd || goto err
 
-    boot kernel initrd=initrd init=${installer.config.system.build.toplevel}/init loglevel=4 || goto err
+    boot kernel initrd=initrd init=${installer.config.system.build.toplevel}/init nixos.install=${installer-script} loglevel=4 || goto err
 
     :err
     shell
@@ -68,12 +84,6 @@ in
       openFirewall = true;
     };
 
-  # Ensure the intaller script and therefore the client system is part of the
-  # store so it can be fetched by the installer.
-  boot.postBootCommands = ''
-    ${config.nix.package.out}/bin/nix-env -p /nix/var/nix/profiles/installer --set "${installer.installer}"
-  '';
-
   networking.extraHosts = ''
     127.0.0.1 boot.${config.networking.domain}
   '';