nixos: nix.readOnlyStore -> boot.readOnlyNixStore

The placement of this option under `nix` was misleading, as it is not
configuration of the Nix daemon, but rather configuration of the NixOS
boot process and how it mounts the Nix store. As such, make it an option
of `boot` to clarify what it actually affects, and imply that it will
only take effect on a reboot.

Since it no longer has the context of nix, adjust the name to include
it.

nixos/doc/manual/from_md/release-notes/rl-2305.section.xml

@@ -78,6 +78,13 @@
           relying on this should provide their own implementation.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          The <literal>nix.readOnlyStore</literal> option has been
+          renamed to <literal>boot.readOnlyNixStore</literal> to clarify
+          that it configures the NixOS boot process, not the Nix daemon.
+        </para>
+      </listitem>
     </itemizedlist>
   </section>
   <section xml:id="sec-release-23.05-notable-changes">

nixos/doc/manual/release-notes/rl-2305.section.md

@@ -29,6 +29,8 @@ In addition to numerous new and upgraded packages, this release has the followin
 
 - The EC2 image module previously detected and activated swap-formatted instance store devices and partitions in stage-1 (initramfs). This behaviour has been removed. Users relying on this should provide their own implementation.
 
+- 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}
 
 <!-- To avoid merge conflicts, consider adding your item at an arbitrary place in the list instead. -->

nixos/modules/services/misc/nix-daemon.nix

@@ -115,6 +115,7 @@ in
     (mkRenamedOptionModuleWith { sinceRelease = 2003; from = [ "nix" "useChroot" ]; to = [ "nix" "useSandbox" ]; })
     (mkRenamedOptionModuleWith { sinceRelease = 2003; from = [ "nix" "chrootDirs" ]; to = [ "nix" "sandboxPaths" ]; })
     (mkRenamedOptionModuleWith { sinceRelease = 2205; from = [ "nix" "daemonIONiceLevel" ]; to = [ "nix" "daemonIOSchedPriority" ]; })
+    (mkRenamedOptionModuleWith { sinceRelease = 2211; from = [ "nix" "readOnlyStore" ]; to = [ "boot" "readOnlyNixStore" ]; })
     (mkRemovedOptionModule [ "nix" "daemonNiceLevel" ] "Consider nix.daemonCPUSchedPolicy instead.")
   ] ++ mapAttrsToList (oldConf: newConf: mkRenamedOptionModuleWith { sinceRelease = 2205; from = [ "nix" oldConf ]; to = [ "nix" "settings" newConf ]; }) legacyConfMappings;
 
@@ -366,17 +367,6 @@ in
         '';
       };
 
-      readOnlyStore = mkOption {
-        type = types.bool;
-        default = true;
-        description = lib.mdDoc ''
-          If set, NixOS will enforce the immutability of the Nix store
-          by making {file}`/nix/store` a read-only bind
-          mount.  Nix will automatically make the store writable when
-          needed.
-        '';
-      };
-
       nixPath = mkOption {
         type = types.listOf types.str;
         default = [

nixos/modules/system/boot/stage-2-init.sh

@@ -68,7 +68,7 @@ fi
 # like squashfs.
 chown -f 0:30000 /nix/store
 chmod -f 1775 /nix/store
-if [ -n "@readOnlyStore@" ]; then
+if [ -n "@readOnlyNixStore@" ]; then
     if ! [[ "$(findmnt --noheadings --output OPTIONS /nix/store)" =~ ro(,|$) ]]; then
         if [ -z "$container" ]; then
             mount --bind /nix/store /nix/store

nixos/modules/system/boot/stage-2.nix

@@ -10,9 +10,8 @@ let
     src = ./stage-2-init.sh;
     shellDebug = "${pkgs.bashInteractive}/bin/bash";
     shell = "${pkgs.bash}/bin/bash";
-    inherit (config.boot) systemdExecutable extraSystemdUnitPaths;
+    inherit (config.boot) readOnlyNixStore systemdExecutable extraSystemdUnitPaths;
     isExecutable = true;
-    inherit (config.nix) readOnlyStore;
     inherit useHostResolvConf;
     inherit (config.system.build) earlyMountScript;
     path = lib.makeBinPath ([
@@ -42,6 +41,17 @@ in
         '';
       };
 
+      readOnlyNixStore = mkOption {
+        type = types.bool;
+        default = true;
+        description = lib.mdDoc ''
+          If set, NixOS will enforce the immutability of the Nix store
+          by making {file}`/nix/store` a read-only bind
+          mount.  Nix will automatically make the store writable when
+          needed.
+        '';
+      };
+
       systemdExecutable = mkOption {
         default = "/run/current-system/systemd/lib/systemd/systemd";
         type = types.str;