Merge pull request #254993 from helsinki-systems/feat/stc-mount-improvements

nixos/switch-to-configuration: Mount improvements and a lot more test cases

nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md

@@ -21,8 +21,9 @@ If the action is `switch` or `test`, the currently running system is inspected
 and the actions to switch to the new system are calculated. This process takes
 two data sources into account: `/etc/fstab` and the current systemd status.
 Mounts and swaps are read from `/etc/fstab` and the corresponding actions are
-generated. If a new mount is added, for example, the proper `.mount` unit is
+generated. If the options of a mount are modified, for example, the proper `.mount`
-marked to be started. The current systemd state is inspected, the difference
+unit is reloaded (or restarted if anything else changed and it's neither the root
+mount or the nix store). The current systemd state is inspected, the difference
 between the current system and the desired configuration is calculated and
 actions are generated to get to this state. There are a lot of nuances that can
 be controlled by the units which are explained here.

nixos/modules/system/activation/switch-to-configuration.pl

@@ -74,7 +74,7 @@ if ("@localeArchive@" ne "") {
 
 if (!defined($action) || ($action ne "switch" && $action ne "boot" && $action ne "test" && $action ne "dry-activate")) {
     print STDERR <<"EOF";
-Usage: $0 [switch|boot|test]
+Usage: $0 [switch|boot|test|dry-activate]
 
 switch:       make the configuration the boot default and activate now
 boot:         make the configuration the boot default
@@ -661,10 +661,20 @@ foreach my $mount_point (keys(%{$cur_fss})) {
         # Filesystem entry disappeared, so unmount it.
         $units_to_stop{$unit} = 1;
     } elsif ($cur->{fsType} ne $new->{fsType} || $cur->{device} ne $new->{device}) {
+        if ($mount_point eq '/' or $mount_point eq '/nix') {
+            if ($cur->{options} ne $new->{options}) {
+                # Mount options changed, so remount it.
+                $units_to_reload{$unit} = 1;
+                record_unit($reload_list_file, $unit);
+            } else {
+                # Don't unmount / or /nix if the device changed
+                $units_to_skip{$unit} = 1;
+            }
+        } else {
             # Filesystem type or device changed, so unmount and mount it.
-        $units_to_stop{$unit} = 1;
+            $units_to_restart{$unit} = 1;
-        $units_to_start{$unit} = 1;
+            record_unit($restart_list_file, $unit);
-        record_unit($start_list_file, $unit);
+        }
     } elsif ($cur->{options} ne $new->{options}) {
         # Mount options changes, so remount it.
         $units_to_reload{$unit} = 1;

nixos/tests/switch-test.nix

@@ -58,6 +58,37 @@ in {
       '');
 
       specialisation = rec {
+        brokenInitInterface.configuration.config.system.extraSystemBuilderCmds = ''
+          echo "systemd 0" > $out/init-interface-version
+        '';
+
+        modifiedSystemConf.configuration.systemd.extraConfig = ''
+          # Hello world!
+        '';
+
+        addedMount.configuration.virtualisation.fileSystems."/test" = {
+          device = "tmpfs";
+          fsType = "tmpfs";
+        };
+
+        addedMountOptsModified.configuration = {
+          imports = [ addedMount.configuration ];
+          virtualisation.fileSystems."/test".options = [ "x-test" ];
+        };
+
+        addedMountDevModified.configuration = {
+          imports = [ addedMountOptsModified.configuration ];
+          virtualisation.fileSystems."/test".device = lib.mkForce "ramfs";
+        };
+
+        storeMountModified.configuration = {
+          virtualisation.fileSystems."/".device = lib.mkForce "auto";
+        };
+
+        swap.configuration.swapDevices = lib.mkVMOverride [
+          { device = "/swapfile"; size = 1; }
+        ];
+
         simpleService.configuration = {
           systemd.services.test = {
             wantedBy = [ "multi-user.target" ];
@@ -643,6 +674,97 @@ in {
 
         # test and dry-activate actions are tested further down below
 
+        # invalid action fails the script
+        switch_to_specialisation("${machine}", "", action="broken-action", fail=True)
+        # no action fails the script
+        assert "Usage:" in machine.fail("${machine}/bin/switch-to-configuration 2>&1")
+
+    with subtest("init interface version"):
+        # Do not try to switch to an invalid init interface version
+        assert "incompatible" in switch_to_specialisation("${machine}", "brokenInitInterface", fail=True)
+
+    with subtest("systemd restarts"):
+        # systemd is restarted when its system.conf changes
+        out = switch_to_specialisation("${machine}", "modifiedSystemConf")
+        assert_contains(out, "restarting systemd...")
+
+    with subtest("continuing from an aborted switch"):
+        # An aborted switch will write into a file what it tried to start
+        # and a second switch should continue from this
+        machine.succeed("echo dbus.service > /run/nixos/start-list")
+        out = switch_to_specialisation("${machine}", "modifiedSystemConf")
+        assert_contains(out, "starting the following units: dbus.service\n")
+
+    with subtest("fstab mounts"):
+        switch_to_specialisation("${machine}", "")
+        # add a mountpoint
+        out = switch_to_specialisation("${machine}", "addedMount")
+        assert_lacks(out, "stopping the following units:")
+        assert_lacks(out, "NOT restarting the following changed units:")
+        assert_lacks(out, "\nrestarting the following units:")
+        assert_lacks(out, "\nstarting the following units:")
+        assert_contains(out, "the following new units were started: test.mount\n")
+        # modify the mountpoint's options
+        out = switch_to_specialisation("${machine}", "addedMountOptsModified")
+        assert_lacks(out, "stopping the following units:")
+        assert_lacks(out, "NOT restarting the following changed units:")
+        assert_contains(out, "reloading the following units: test.mount\n")
+        assert_lacks(out, "\nrestarting the following units:")
+        assert_lacks(out, "\nstarting the following units:")
+        assert_lacks(out, "the following new units were started:")
+        # modify the device
+        out = switch_to_specialisation("${machine}", "addedMountDevModified")
+        assert_lacks(out, "stopping the following units:")
+        assert_lacks(out, "NOT restarting the following changed units:")
+        assert_lacks(out, "reloading the following units:")
+        assert_contains(out, "\nrestarting the following units: test.mount\n")
+        assert_lacks(out, "\nstarting the following units:")
+        assert_lacks(out, "the following new units were started:")
+        # modify both
+        out = switch_to_specialisation("${machine}", "addedMount")
+        assert_lacks(out, "stopping the following units:")
+        assert_lacks(out, "NOT restarting the following changed units:")
+        assert_lacks(out, "reloading the following units:")
+        assert_contains(out, "\nrestarting the following units: test.mount\n")
+        assert_lacks(out, "\nstarting the following units:")
+        assert_lacks(out, "the following new units were started:")
+        # remove the mount
+        out = switch_to_specialisation("${machine}", "")
+        assert_contains(out, "stopping the following units: test.mount\n")
+        assert_lacks(out, "NOT restarting the following changed units:")
+        assert_contains(out, "reloading the following units: dbus.service\n")
+        assert_lacks(out, "\nrestarting the following units:")
+        assert_lacks(out, "\nstarting the following units:")
+        assert_lacks(out, "the following new units were started:")
+        # change something about the / mount
+        out = switch_to_specialisation("${machine}", "storeMountModified")
+        assert_lacks(out, "stopping the following units:")
+        assert_contains(out, "NOT restarting the following changed units: -.mount")
+        assert_contains(out, "reloading the following units: dbus.service\n")
+        assert_lacks(out, "\nrestarting the following units:")
+        assert_lacks(out, "\nstarting the following units:")
+        assert_lacks(out, "the following new units were started:")
+
+    with subtest("swaps"):
+        switch_to_specialisation("${machine}", "")
+        # add a swap
+        out = switch_to_specialisation("${machine}", "swap")
+        assert_lacks(out, "stopping the following units:")
+        assert_lacks(out, "NOT restarting the following changed units:")
+        assert_contains(out, "reloading the following units: dbus.service\n")
+        assert_lacks(out, "\nrestarting the following units:")
+        assert_lacks(out, "\nstarting the following units:")
+        assert_contains(out, "the following new units were started: swapfile.swap")
+        # remove it
+        out = switch_to_specialisation("${machine}", "")
+        assert_contains(out, "stopping swap device: /swapfile")
+        assert_lacks(out, "stopping the following units:")
+        assert_lacks(out, "NOT restarting the following changed units:")
+        assert_contains(out, "reloading the following units: dbus.service\n")
+        assert_lacks(out, "\nrestarting the following units:")
+        assert_lacks(out, "\nstarting the following units:")
+        assert_lacks(out, "the following new units were started:")
+
     with subtest("services"):
         switch_to_specialisation("${machine}", "")
         # Nothing happens when nothing is changed