commit 85c1c30fd9ab350ad254736d0950d07639b9f6e8 · pyrox.dev/nixpkgs

+3 -2

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

···

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       and the actions to switch to the new system are calculated. This process takes

     

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       two data sources into account: `/etc/fstab` and the current systemd status.

     

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       Mounts and swaps are read from `/etc/fstab` and the corresponding actions are

     

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       generated. If a new mount is added, for example, the proper `.mount` unit is

     

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       marked to be started. The current systemd state is inspected, the difference

     

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       generated. If the options of a mount are modified, for example, the proper `.mount`

     

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       unit is reloaded (or restarted if anything else changed and it's neither the root

     

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       mount or the nix store). The current systemd state is inspected, the difference

     

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       between the current system and the desired configuration is calculated and

     

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       actions are generated to get to this state. There are a lot of nuances that can

     

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       be controlled by the units which are explained here.

+14 -4

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

···

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               # Filesystem entry disappeared, so unmount it.

     

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               $units_to_stop{$unit} = 1;

     

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           } elsif ($cur->{fsType} ne $new->{fsType} || $cur->{device} ne $new->{device}) {

     

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               # Filesystem type or device changed, so unmount and mount it.

     

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               $units_to_stop{$unit} = 1;

     

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               $units_to_start{$unit} = 1;

     

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               record_unit($start_list_file, $unit);

     

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               if ($mount_point eq '/' or $mount_point eq '/nix') {

     

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                   if ($cur->{options} ne $new->{options}) {

     

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                       # Mount options changed, so remount it.

     

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                       $units_to_reload{$unit} = 1;

     

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                       record_unit($reload_list_file, $unit);

     

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                   } else {

     

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                       # Don't unmount / or /nix if the device changed

     

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                       $units_to_skip{$unit} = 1;

     

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                   }

     

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               } else {

     

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                   # Filesystem type or device changed, so unmount and mount it.

     

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                   $units_to_restart{$unit} = 1;

     

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                   record_unit($restart_list_file, $unit);

     

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               }

     

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           } elsif ($cur->{options} ne $new->{options}) {

     

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               # Mount options changes, so remount it.

     

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               $units_to_reload{$unit} = 1;

+69

nixos/tests/switch-test.nix

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                 # Hello world!

     

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               '';

     

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               addedMount.configuration.virtualisation.fileSystems."/test" = {

     

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                 device = "tmpfs";

     

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                 fsType = "tmpfs";

     

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               };

     

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               addedMountOptsModified.configuration = {

     

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                 imports = [ addedMount.configuration ];

     

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                 virtualisation.fileSystems."/test".options = [ "x-test" ];

     

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               };

     

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               addedMountDevModified.configuration = {

     

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                 imports = [ addedMountOptsModified.configuration ];

     

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                 virtualisation.fileSystems."/test".device = lib.mkForce "ramfs";

     

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               };

     

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               storeMountModified.configuration = {

     

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                 virtualisation.fileSystems."/".device = lib.mkForce "auto";

     

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               };

     

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               simpleService.configuration = {

     

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                 systemd.services.test = {

     

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                   wantedBy = [ "multi-user.target" ];

     
···

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               machine.succeed("echo dbus.service > /run/nixos/start-list")

     

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               out = switch_to_specialisation("${machine}", "modifiedSystemConf")

     

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               assert_contains(out, "starting the following units: dbus.service\n")

     

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       +
       

     

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           with subtest("fstab mounts"):

     

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               switch_to_specialisation("${machine}", "")

     

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               # add a mountpoint

     

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               out = switch_to_specialisation("${machine}", "addedMount")

     

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               assert_lacks(out, "stopping the following units:")

     

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               assert_lacks(out, "NOT restarting the following changed units:")

     

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               assert_lacks(out, "\nrestarting the following units:")

     

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               assert_lacks(out, "\nstarting the following units:")

     

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               assert_contains(out, "the following new units were started: test.mount\n")

     

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               # modify the mountpoint's options

     

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               out = switch_to_specialisation("${machine}", "addedMountOptsModified")

     

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               assert_lacks(out, "stopping the following units:")

     

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               assert_lacks(out, "NOT restarting the following changed units:")

     

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               assert_contains(out, "reloading the following units: test.mount\n")

     

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               assert_lacks(out, "\nrestarting the following units:")

     

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               assert_lacks(out, "\nstarting the following units:")

     

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               assert_lacks(out, "the following new units were started:")

     

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               # modify the device

     

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               out = switch_to_specialisation("${machine}", "addedMountDevModified")

     

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               assert_lacks(out, "stopping the following units:")

     

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               assert_lacks(out, "NOT restarting the following changed units:")

     

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               assert_lacks(out, "reloading the following units:")

     

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               assert_contains(out, "\nrestarting the following units: test.mount\n")

     

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               assert_lacks(out, "\nstarting the following units:")

     

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               assert_lacks(out, "the following new units were started:")

     

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               # modify both

     

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               out = switch_to_specialisation("${machine}", "addedMount")

     

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               assert_lacks(out, "stopping the following units:")

     

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               assert_lacks(out, "NOT restarting the following changed units:")

     

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               assert_lacks(out, "reloading the following units:")

     

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               assert_contains(out, "\nrestarting the following units: test.mount\n")

     

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               assert_lacks(out, "\nstarting the following units:")

     

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               assert_lacks(out, "the following new units were started:")

     

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               # remove the mount

     

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               out = switch_to_specialisation("${machine}", "")

     

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               assert_contains(out, "stopping the following units: test.mount\n")

     

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               assert_lacks(out, "NOT restarting the following changed units:")

     

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               assert_contains(out, "reloading the following units: dbus.service\n")

     

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               assert_lacks(out, "\nrestarting the following units:")

     

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               assert_lacks(out, "\nstarting the following units:")

     

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               assert_lacks(out, "the following new units were started:")

     

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               # change something about the / mount

     

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               out = switch_to_specialisation("${machine}", "storeMountModified")

     

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               assert_lacks(out, "stopping the following units:")

     

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               assert_contains(out, "NOT restarting the following changed units: -.mount")

     

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               assert_contains(out, "reloading the following units: dbus.service\n")

     

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               assert_lacks(out, "\nrestarting the following units:")

     

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               assert_lacks(out, "\nstarting the following units:")

     

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               assert_lacks(out, "the following new units were started:")

     

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           with subtest("services"):

     

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               switch_to_specialisation("${machine}", "")