Rename PXE installer menu entry, add vanilla NixOS minimal netboot entry

The iPXE menu's "nixos" entry actually chain-loads this flake's own
custom auto-installer image, not a stock NixOS image — rename it to
"auto-installer" (label "NixOS Auto-Installer") so the menu says what it
boots, and set networking.hostName on netbootSystem to match, so the
generated system name (nixos-system-auto-installer-*) and staged
directory (/srv/pxe/http/auto-installer) agree with the menu entry too.

Add a second, genuinely vanilla NixOS minimal netboot image
(netbootMinimalSystem in flake.nix — nixpkgs' netboot-minimal.nix on its
own, none of modules/installer/common.nix's auto-installer wiring),
built from source the same way as the auto-installer image and exposed
as packages.x86_64-linux.pxe-minimal. Staged and menu-wired the same
way, as "nixos-minimal" (item, hostname, and directory all matching).

modules/pxe-boot/stage-installer-artifacts.nix is generalized to stage
both images via a shared rule-builder instead of one hardcoded set of
paths.

Verified: nix eval confirms both images' config.system.name matches
their menu entry/directory names, the pxe-boot host itself builds
clean with the new menu.ipxe, and the new pxe-minimal image was booted
directly under QEMU (kernel+initrd, no KVM) to a working login shell
with hostname nixos-minimal, no hang.

docs/auto-installer.md

@@ -150,7 +150,11 @@ use case.
 
 The `pxe` variant is also built automatically as part of the `pxe-boot` host
 itself (`modules/pxe-boot/stage-installer-artifacts.nix`) and served over
-iPXE — see `docs/pxe-boot.md`.
+iPXE as the menu's "NixOS Auto-Installer" entry — see `docs/pxe-boot.md`.
+That same host also builds and serves `packages.x86_64-linux.pxe-minimal`,
+a vanilla NixOS minimal netboot image with none of this auto-installer's
+wiring, as a separate "NixOS Minimal" menu entry — also documented in
+`docs/pxe-boot.md`, not covered further here since it's not this installer.
 
 ## Host keys
 

docs/pxe-boot.md

@@ -1,9 +1,10 @@
 # pxe-boot
 
-The `pxe-boot` host serves HTTP boot assets for iPXE clients — including a
-self-staged copy of this flake's own auto-installer netboot image, see
-`docs/auto-installer.md` for what that image actually is and does once
-booted.
+The `pxe-boot` host serves HTTP boot assets for iPXE clients — including
+self-staged copies of both this flake's own auto-installer netboot image
+(see `docs/auto-installer.md` for what that image actually is and does once
+booted) and a vanilla, unmodified NixOS minimal netboot image for plain
+rescue/inspection use.
 
 ## Host Role
 
@@ -28,7 +29,8 @@ The host creates these directories with systemd tmpfiles:
 /srv/pxe
 /srv/pxe/http
 /srv/pxe/http/images
-/srv/pxe/http/nixos
+/srv/pxe/http/auto-installer
+/srv/pxe/http/nixos-minimal
 /srv/pxe/http/systemrescue
 /srv/pxe/http/ubuntu
 /srv/pxe/http/rescue
@@ -37,7 +39,7 @@ The host creates these directories with systemd tmpfiles:
 
 Mount shared image storage under `/srv/pxe/http`, preferably
 `/srv/pxe/http/images` unless a menu entry expects files in a specific
-directory such as `/srv/pxe/http/nixos`.
+directory such as `/srv/pxe/http/auto-installer`.
 
 The HTTP iPXE chain is:
 
@@ -50,20 +52,37 @@ undionly.kpxe or ipxe.efi
 
 The generated menu currently exposes entries for:
 
-- NixOS installer
+- NixOS Auto-Installer
+- NixOS Minimal
 - SystemRescue environment
 - iPXE shell
 - Reboot
 
-The NixOS installer entry chain-loads `/srv/pxe/http/nixos/netboot.ipxe`,
-which is nixpkgs' own generated netboot iPXE script (correct `init=`/`initrd=`
-kernel parameters included) rather than a hand-rolled boot line — that script
-in turn expects its kernel/initrd siblings in the same directory. All three
-files (`bzImage`, `initrd`, `netboot.ipxe`) are built from this flake's own
-`modules/installer/iso.nix` netboot image (the same one `nix build .#pxe`
-produces) and staged automatically by
-`modules/pxe-boot/stage-installer-artifacts.nix` via `systemd.tmpfiles.rules`
-— no manual operator step required.
+Both NixOS entries chain-load a `netboot.ipxe` staged into their own
+directory (`/srv/pxe/http/auto-installer/netboot.ipxe` and
+`/srv/pxe/http/nixos-minimal/netboot.ipxe`), each nixpkgs' own generated
+netboot iPXE script (correct `init=`/`initrd=` kernel parameters included)
+rather than a hand-rolled boot line — that script in turn expects its
+kernel/initrd siblings in the same directory. Each directory's three files
+(`bzImage`, `initrd`, `netboot.ipxe`) are built from source and staged
+automatically by `modules/pxe-boot/stage-installer-artifacts.nix` via
+`systemd.tmpfiles.rules` — no manual operator step required:
+
+- `auto-installer` is this flake's own `netbootSystem` (`flake.nix`) — the
+  same auto-installer image `nix build .#pxe` produces. See
+  `docs/auto-installer.md`.
+- `nixos-minimal` is `netbootMinimalSystem` (`flake.nix`) — nixpkgs'
+  `netboot-minimal.nix` composed on its own, with none of this flake's
+  auto-installer wiring (no `common.nix`, no `auto-install.sh`, no baked
+  host keys or custom users). Same `nix build .#pxe-minimal` mechanism as
+  the auto-installer image, just a different module composition. Useful
+  as a plain rescue/inspection shell that doesn't assume anything about
+  this flake.
+
+Both images set `networking.hostName` to match their menu entry/staged
+directory name (`auto-installer` / `nixos-minimal`), so each one's
+generated system name (`nixos-system-<name>-*`) is self-describing rather
+than the nixpkgs default of `nixos-system-nixos-*` for both.
 
 The SystemRescue entry expects the source ISO at:
 

flake.nix

@@ -65,7 +65,7 @@
           # file without a same-option circular dependency (a module
           # contributing to environment.etc can't read the merged
           # environment.etc it's itself contributing to).
-          specialArgs = { inherit inputs vars netbootSystem flakeTarget; };
+          specialArgs = { inherit inputs vars netbootSystem netbootMinimalSystem flakeTarget; };
         };
 
       # Generated platform x build-type matrix. pxe-boot has no linode
@@ -133,6 +133,12 @@
       # profiles/installation-device.nix independently, so common.nix's
       # initialHashedPassword override (which assumes that profile is
       # present) still applies correctly without iso.nix in the mix.
+      #
+      # networking.hostName is set explicitly (rather than left at nixpkgs'
+      # own "nixos" default) so this image's generated system name
+      # (nixos-system-auto-installer-*) matches its iPXE menu entry —
+      # see modules/build-types/pxe-boot.nix's :auto-installer item — and
+      # its staged directory, /srv/pxe/http/auto-installer.
       netbootSystem = nixpkgs.lib.nixosSystem {
         inherit system;
         modules = [
@@ -142,10 +148,32 @@
               (modulesPath + "/installer/netboot/netboot-minimal.nix")
             ];
           })
+          { networking.hostName = "auto-installer"; }
         ];
         specialArgs = { inherit vars; };
       };
 
+      # A genuinely vanilla NixOS minimal netboot image: nixpkgs'
+      # netboot-minimal.nix on its own, with none of this flake's
+      # auto-installer wiring (no common.nix — no auto-install.sh, no
+      # baked host keys, no custom users/passwords). Built from source via
+      # the same nixosSystem + netboot-minimal.nix path as netbootSystem
+      # above, so both go through an identical build mechanism; the only
+      # difference is what's composed in. hostName again matches this
+      # image's iPXE menu entry (:nixos-minimal) and staged directory
+      # (/srv/pxe/http/nixos-minimal).
+      netbootMinimalSystem = nixpkgs.lib.nixosSystem {
+        inherit system;
+        modules = [
+          ({ modulesPath, ... }: {
+            imports = [
+              (modulesPath + "/installer/netboot/netboot-minimal.nix")
+            ];
+          })
+          { networking.hostName = "nixos-minimal"; }
+        ];
+      };
+
     in
     {
 
@@ -167,6 +195,15 @@
           { name = "initrd"; path = netbootSystem.config.system.build.netbootRamdisk; }
           { name = "kernel"; path = netbootSystem.config.system.build.kernel; }
         ];
+
+        # Vanilla NixOS minimal netboot bundle — see netbootMinimalSystem
+        # above. Staged onto the pxe-boot host alongside packages.pxe by
+        # modules/pxe-boot/stage-installer-artifacts.nix.
+        pxe-minimal = pkgs.linkFarm "pxe-minimal" [
+          { name = "netboot.ipxe"; path = netbootMinimalSystem.config.system.build.netbootIpxeScript; }
+          { name = "initrd"; path = netbootMinimalSystem.config.system.build.netbootRamdisk; }
+          { name = "kernel"; path = netbootMinimalSystem.config.system.build.kernel; }
+        ];
       };
     };
 }

modules/build-types/pxe-boot.nix

@@ -68,15 +68,19 @@ let
     set base ${pxeBaseUrl}
 
     menu PXE Boot Menu
-    item nixos NixOS Installer
+    item auto-installer NixOS Auto-Installer
+    item nixos-minimal NixOS Minimal
     item rescue Rescue Environment
     item shell iPXE Shell
     item reboot Reboot
 
     choose target && goto ''${target}
 
-    :nixos
-    chain ''${base}/nixos/netboot.ipxe
+    :auto-installer
+    chain ''${base}/auto-installer/netboot.ipxe
+
+    :nixos-minimal
+    chain ''${base}/nixos-minimal/netboot.ipxe
 
     :rescue
     chain ''${base}/systemrescue.ipxe
@@ -129,7 +133,8 @@ in
     "d ${pxeRoot} 0755 root root -"
     "d ${httpRoot} 0755 root root -"
     "d ${httpRoot}/images 0755 root root -"
-    "d ${httpRoot}/nixos 0755 root root -"
+    "d ${httpRoot}/auto-installer 0755 root root -"
+    "d ${httpRoot}/nixos-minimal 0755 root root -"
     "d ${httpRoot}/systemrescue 0755 root root -"
     "d ${httpRoot}/ubuntu 0755 root root -"
     "d ${httpRoot}/rescue 0755 root root -"

modules/pxe-boot/stage-installer-artifacts.nix

@@ -1,23 +1,32 @@
-{ netbootSystem, ... }:
+{ netbootSystem, netbootMinimalSystem, ... }:
 
 let
   # config.system.build.kernel and .netbootRamdisk are directories, not the
   # files themselves — nixpkgs' own system.build.kexecTree does the same
   # ${...}/<file> dereference for the same reason.
-  inherit (netbootSystem.config.system.boot.loader) kernelFile;
+  mkStageRules = { dirName, system }:
+    let
+      inherit (system.config.system.boot.loader) kernelFile;
+      dir = "/srv/pxe/http/${dirName}";
     in
-{
-  # Builds this flake's own installer netboot image (the same one
-  # `nix build .#pxe` produces) and stages it where menu.ipxe's :nixos
-  # entry expects it, so the pxe-boot host is self-contained — no manual
-  # operator step to populate /srv/pxe/http/nixos after deploy.
-  systemd.tmpfiles.rules = [
+    [
       # Declared here too (not just in build-types/pxe-boot.nix) so this
       # module's C+ rules don't depend on cross-module list-merge ordering —
       # tmpfiles' C type needs the target directory to already exist.
-    "d /srv/pxe/http/nixos 0755 root root -"
-    "C+ /srv/pxe/http/nixos/${kernelFile} 0644 root root - ${netbootSystem.config.system.build.kernel}/${kernelFile}"
-    "C+ /srv/pxe/http/nixos/initrd 0644 root root - ${netbootSystem.config.system.build.netbootRamdisk}/initrd"
-    "C+ /srv/pxe/http/nixos/netboot.ipxe 0644 root root - ${netbootSystem.config.system.build.netbootIpxeScript}/netboot.ipxe"
+      "d ${dir} 0755 root root -"
+      "C+ ${dir}/${kernelFile} 0644 root root - ${system.config.system.build.kernel}/${kernelFile}"
+      "C+ ${dir}/initrd 0644 root root - ${system.config.system.build.netbootRamdisk}/initrd"
+      "C+ ${dir}/netboot.ipxe 0644 root root - ${system.config.system.build.netbootIpxeScript}/netboot.ipxe"
     ];
+in
+{
+  # Builds this flake's own installer netboot image (the same one
+  # `nix build .#pxe` produces) plus the vanilla NixOS minimal netboot image
+  # (`nix build .#pxe-minimal`), and stages both where menu.ipxe's
+  # :auto-installer / :nixos-minimal entries expect them, so the pxe-boot
+  # host is self-contained — no manual operator step to populate
+  # /srv/pxe/http after deploy.
+  systemd.tmpfiles.rules =
+    mkStageRules { dirName = "auto-installer"; system = netbootSystem; }
+    ++ mkStageRules { dirName = "nixos-minimal"; system = netbootMinimalSystem; };
 }