Fix local building for remote hosts

patches/210382.patch

@@ -0,0 +1,96 @@
+From cc4de1aa3ad39c480e111113aec48da2e7c24e8d Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Fabian=20M=C3=B6ller?= <fabianm88@gmail.com>
+Date: Fri, 13 Jan 2023 10:16:46 +0100
+Subject: [PATCH] nixos-rebuild: Allow local builds when --target-host is used
+ again
+
+This is a followup of #148921, to allow local builds when
+`--target-host` is used again. It also documents the change in
+behavior, regarding the specialty of the `localhost` value.
+
+By removing the special handling of an empty `buildHost` and non empty
+`targetHost`, this change also slightly alters the behavior of
+`nixos-rebuild`.
+
+Originally by specifying `--target-host target --build-host ""`, the
+now removed special case would transform those arguments to
+`--target-host target --build-host target`.
+Now the empty `--build-host` would result in a local build.
+---
+ .../doc/manual/from_md/release-notes/rl-2305.section.xml | 9 +++++++++
+ nixos/doc/manual/man-nixos-rebuild.xml                   | 6 +++---
+ nixos/doc/manual/release-notes/rl-2305.section.md        | 2 ++
+ pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.sh    | 4 ----
+ 4 files changed, 14 insertions(+), 7 deletions(-)
+
+diff --git a/nixos/doc/manual/from_md/release-notes/rl-2305.section.xml b/nixos/doc/manual/from_md/release-notes/rl-2305.section.xml
+index 242841a56b65b..7a8c7b10596a8 100644
+--- a/nixos/doc/manual/from_md/release-notes/rl-2305.section.xml
++++ b/nixos/doc/manual/from_md/release-notes/rl-2305.section.xml
+@@ -256,6 +256,15 @@
+           been changed to <literal>null</literal>.
+         </para>
+       </listitem>
++      <listitem>
++        <para>
++          The <literal>--target-host</literal> and
++          <literal>--build-host</literal> options of
++          <literal>nixos-rebuild</literal> no longer treat the
++          <literal>localhost</literal> value specially – to build
++          on/deploy to local machine, omit the relevant flag.
++        </para>
++      </listitem>
+       <listitem>
+         <para>
+           The <literal>nix.readOnlyStore</literal> option has been
+diff --git a/nixos/doc/manual/man-nixos-rebuild.xml b/nixos/doc/manual/man-nixos-rebuild.xml
+index cab871661a755..1b55d07c95022 100644
+--- a/nixos/doc/manual/man-nixos-rebuild.xml
++++ b/nixos/doc/manual/man-nixos-rebuild.xml
+@@ -532,15 +532,15 @@
+     <listitem>
+      <para>
+       Specifies the NixOS target host. By setting this to something other than
+-      <replaceable>localhost</replaceable>, the system activation will happen
++      an empty string, the system activation will happen
+       on the remote host instead of the local machine. The remote host needs to
+       be accessible over ssh, and for the commands <option>switch</option>,
+       <option>boot</option> and <option>test</option> you need root access.
+      </para>
+ 
+      <para>
+-      If <option>--build-host</option> is not explicitly specified, building
+-      will take place locally.
++      If <option>--build-host</option> is not explicitly specified or empty,
++      building will take place locally.
+      </para>
+ 
+      <para>
+diff --git a/nixos/doc/manual/release-notes/rl-2305.section.md b/nixos/doc/manual/release-notes/rl-2305.section.md
+index b5c74836ef407..f6c71cc3da0ad 100644
+--- a/nixos/doc/manual/release-notes/rl-2305.section.md
++++ b/nixos/doc/manual/release-notes/rl-2305.section.md
+@@ -67,6 +67,8 @@ In addition to numerous new and upgraded packages, this release has the followin
+ 
+ - In `mastodon` it is now necessary to specify location of file with `PostgreSQL` database password. In `services.mastodon.database.passwordFile` parameter default value `/var/lib/mastodon/secrets/db-password` has been changed to `null`.
+ 
++- The `--target-host` and `--build-host` options of `nixos-rebuild` no longer treat the `localhost` value specially – to build on/deploy to local machine, omit the relevant flag.
++
+ - The `nix.readOnlyStore` option has been renamed to `boot.readOnlyNixStore` to clarify that it configures the NixOS boot process, not the Nix daemon.
+ 
+ ## Other Notable Changes {#sec-release-23.05-notable-changes}
+diff --git a/pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.sh b/pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.sh
+index 217e04d35720e..ed7c9231905a3 100755
+--- a/pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.sh
++++ b/pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.sh
+@@ -148,10 +148,6 @@ if [[ -n "$SUDO_USER" || -n $remoteSudo ]]; then
+     maybeSudo=(sudo --preserve-env="$preservedSudoVars" --)
+ fi
+ 
+-if [[ -z "$buildHost" && -n "$targetHost" ]]; then
+-    buildHost="$targetHost"
+-fi
+-
+ # log the given argument to stderr if verbose mode is on
+ logVerbose() {
+     if [ -n "$verboseScript" ]; then

shells/nixos-config.nix

@@ -1,6 +1,8 @@
 { pkgs, inputs }: pkgs.devshell.mkShell {
   name = "NixOS config";
   packages = [
+    # Use nixos-rebuild from flake, since it might be patched
+    pkgs.nixos-rebuild
     pkgs.nixpkgs-fmt
     (pkgs.writeShellScriptBin "fetchpatch" "curl -L https://github.com/NixOS/nixpkgs/pull/$1.patch -o patches/$1.patch")
     inputs.agenix.defaultPackage.x86_64-linux