From 7b0e0ca35e07a3043f2427e96d5f10478fdc5597 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Wed, 12 May 2021 22:11:17 +0200
Subject: [PATCH] nixos-install-tools: init

The essential commands from the NixOS installer as a package

With this package, you get the commands like nixos-generate-config and
nixos-install that you would otherwise only find on a NixOS system, such
as an installer image.

This way, you can install NixOS using a machine that only has Nix.

It also includes the manpages, which are important because the commands
rely on those for providing --help.
---
 .../installing-from-other-distro.xml          |  8 +--
 .../tools/nix/nixos-install-tools/default.nix | 67 +++++++++++++++++++
 pkgs/top-level/all-packages.nix               |  2 +
 3 files changed, 73 insertions(+), 4 deletions(-)
 create mode 100644 pkgs/tools/nix/nixos-install-tools/default.nix

diff --git a/nixos/doc/manual/installation/installing-from-other-distro.xml b/nixos/doc/manual/installation/installing-from-other-distro.xml
index 43f69b923d1..63d1d52b01b 100644
--- a/nixos/doc/manual/installation/installing-from-other-distro.xml
+++ b/nixos/doc/manual/installation/installing-from-other-distro.xml
@@ -84,12 +84,12 @@ nixpkgs https://nixos.org/channels/nixpkgs-unstable</screen>
    </para>
    <para>
     You'll need <literal>nixos-generate-config</literal> and
-    <literal>nixos-install</literal> and we'll throw in some man pages and
-    <literal>nixos-enter</literal> just in case you want to chroot into your
-    NixOS partition. They are installed by default on NixOS, but you don't have
+    <literal>nixos-install</literal>, but this also makes some man pages
+    and <literal>nixos-enter</literal> available, just in case you want to chroot into your
+    NixOS partition. NixOS installs these by default, but you don't have
     NixOS yet..
    </para>
-<screen><prompt>$ </prompt>nix-env -f '&lt;nixpkgs/nixos&gt;' --arg configuration {} -iA config.system.build.{nixos-generate-config,nixos-install,nixos-enter,manual.manpages}</screen>
+   <screen><prompt>$ </prompt>nix-env -f '&lt;nixpkgs>' -iA nixos-install-tools</screen>
   </listitem>
   <listitem>
    <note>
diff --git a/pkgs/tools/nix/nixos-install-tools/default.nix b/pkgs/tools/nix/nixos-install-tools/default.nix
new file mode 100644
index 00000000000..a129fb34521
--- /dev/null
+++ b/pkgs/tools/nix/nixos-install-tools/default.nix
@@ -0,0 +1,67 @@
+{
+  buildEnv,
+  lib,
+  man,
+  nixos,
+  # TODO: replace indirect self-reference by proper self-reference
+  #       https://github.com/NixOS/nixpkgs/pull/119942
+  nixos-install-tools,
+  runCommand,
+}:
+let
+  inherit (nixos {}) config;
+  version = config.system.nixos.version;
+in
+(buildEnv {
+  name = "nixos-install-tools-${version}";
+  paths = lib.attrValues {
+    # See nixos/modules/installer/tools/tools.nix
+    inherit (config.system.build)
+      nixos-install nixos-generate-config nixos-enter;
+
+    # Required for --help.
+    inherit (config.system.build.manual) manpages;
+  };
+
+  extraOutputsToInstall = ["man"];
+
+  meta = {
+    description = "The essential commands from the NixOS installer as a package";
+    longDescription = ''
+      With this package, you get the commands like nixos-generate-config and
+      nixos-install that you would otherwise only find on a NixOS system, such
+      as an installer image.
+
+      This way, you can install NixOS using a machine that only has Nix.
+    '';
+    license = lib.licenses.mit;
+    homepage = "https://nixos.org";
+    platforms = lib.platforms.linux;
+  };
+
+  passthru.tests = {
+    nixos-install-help = runCommand "test-nixos-install-help" {
+      nativeBuildInputs = [
+        man
+        nixos-install-tools
+      ];
+      meta.description = ''
+        Make sure that --help works. It's somewhat non-trivial because it
+        requires man.
+      '';
+    } ''
+      nixos-install --help | grep -F 'NixOS Reference Pages'
+      nixos-install --help | grep -F 'configuration.nix'
+      nixos-generate-config --help | grep -F 'NixOS Reference Pages'
+      nixos-generate-config --help | grep -F 'hardware-configuration.nix'
+
+      # FIXME: Tries to call unshare, which it must not do for --help
+      # nixos-enter --help | grep -F 'NixOS Reference Pages'
+
+      touch $out
+    '';
+  };
+}).overrideAttrs (o: {
+  inherit version;
+  pname = "nixos-install-tools";
+})
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index da6c96bb2a1..34e142bed82 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -30271,6 +30271,8 @@ in
     (import ../../nixos/lib/make-options-doc/default.nix)
     ({ inherit pkgs lib; } // attrs);
 
+  nixos-install-tools = callPackage ../tools/nix/nixos-install-tools { };
+
   nixui = callPackage ../tools/package-management/nixui { node_webkit = nwjs_0_12; };
 
   nixdoc = callPackage ../tools/nix/nixdoc {};