nixos/system: make switch-to-configuration script pure.

Fixes #28443

Fixed few invocations to `systemctl` to have an absolute path. Additionally add
LOCALE_ARCHIVE so that perl stops spewing warning messages.

3 files changed, 36 insertions, 4 deletions

diff --git a/nixos/modules/system/activation/switch-to-configuration.pl b/nixos/modules/system/activation/switch-to-configuration.pl
index 29cc60b00324..87a4ab2a586d 100644
--- a/nixos/modules/system/activation/switch-to-configuration.pl
+++ b/nixos/modules/system/activation/switch-to-configuration.pl
@@ -16,6 +16,10 @@ my $reloadListFile = "/run/systemd/reload-list";
 
 my $action = shift @ARGV;
 
+if ("@localeArchive@" ne "") {
+    $ENV{LOCALE_ARCHIVE} = "@localeArchive@";
+}
+
 if (!defined $action || ($action ne "switch" && $action ne "boot" && $action ne "test" && $action ne "dry-activate")) {
     print STDERR <<EOF;
 Usage: $0 [switch|boot|test]
@@ -65,7 +69,8 @@ $SIG{PIPE} = "IGNORE";
 sub getActiveUnits {
     # FIXME: use D-Bus or whatever to query this, since parsing the
     # output of list-units is likely to break.
-    my $lines = `LANG= systemctl list-units --full --no-legend`;
+    # Use current version of systemctl binary before daemon is reexeced.
+    my $lines = `LANG= /run/current-system/sw/bin/systemctl list-units --full --no-legend`;
     my $res = {};
     foreach my $line (split '\n', $lines) {
         chomp $line;
@@ -262,7 +267,8 @@ while (my ($unit, $state) = each %{$activePrev}) {
 
 sub pathToUnitName {
     my ($path) = @_;
-    open my $cmd, "-|", "@systemd@/bin/systemd-escape", "--suffix=mount", "-p", $path
+    # Use current version of systemctl binary before daemon is reexeced.
+    open my $cmd, "-|", "/run/current-system/sw/bin/systemd-escape", "--suffix=mount", "-p", $path
         or die "Unable to escape $path!\n";
     my $escaped = join "", <$cmd>;
     chomp $escaped;
@@ -364,7 +370,8 @@ syslog(LOG_NOTICE, "switching to system configuration $out");
 if (scalar (keys %unitsToStop) > 0) {
     print STDERR "stopping the following units: ", join(", ", @unitsToStopFiltered), "\n"
         if scalar @unitsToStopFiltered;
-    system("systemctl", "stop", "--", sort(keys %unitsToStop)); # FIXME: ignore errors?
+    # Use current version of systemctl binary before daemon is reexeced.
+    system("/run/current-system/sw/bin/systemctl", "stop", "--", sort(keys %unitsToStop)); # FIXME: ignore errors?
 }
 
 print STDERR "NOT restarting the following changed units: ", join(", ", sort(keys %unitsToSkip)), "\n"
diff --git a/nixos/modules/system/activation/top-level.nix b/nixos/modules/system/activation/top-level.nix
index 67cb2264e3f3..0c50241f2edf 100644
--- a/nixos/modules/system/activation/top-level.nix
+++ b/nixos/modules/system/activation/top-level.nix
@@ -26,7 +26,6 @@ let
      cloner false config.nesting.children
   ++ cloner true config.nesting.clone;
 
-
   systemBuilder =
     let
       kernelPath = "${config.boot.kernelPackages.kernel}/" +
@@ -83,6 +82,7 @@ let
       done
 
       mkdir $out/bin
+      export localeArchive="${config.i18n.glibcLocales}/lib/locale/locale-archive"
       substituteAll ${./switch-to-configuration.pl} $out/bin/switch-to-configuration
       chmod +x $out/bin/switch-to-configuration
 
diff --git a/nixos/tests/switch-test.nix b/nixos/tests/switch-test.nix
new file mode 100644
index 000000000000..46f2563af8d9
--- /dev/null
+++ b/nixos/tests/switch-test.nix
@@ -0,0 +1,25 @@
+# Test configuration switching.
+
+import ./make-test.nix ({ pkgs, ...} : {
+  name = "switch-test";
+  meta = with pkgs.stdenv.lib.maintainers; {
+    maintainers = [ gleber ];
+  };
+
+  nodes = {
+    machine = { config, lib, pkgs, ... }: {
+      users.mutableUsers = false;
+    };
+    other = { config, lib, pkgs, ... }: {
+      users.mutableUsers = true;
+    };
+  };
+
+  testScript = {nodes, ...}: let
+    originalSystem = nodes.machine.config.system.build.toplevel;
+    otherSystem = nodes.other.config.system.build.toplevel;
+  in ''
+    $machine->succeed("env -i ${originalSystem}/bin/switch-to-configuration test | tee /dev/stderr");
+    $machine->succeed("env -i ${otherSystem}/bin/switch-to-configuration test | tee /dev/stderr");
+  '';
+})