commit cba277a1dcd82e872c75794e4b593dea84520575 · pyrox.dev/nixpkgs

+101 -84
nixos/modules/tasks/filesystems/overlayfs.nix
···

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       { config, lib, pkgs, utils, ... }:

     

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       {

     

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         config,

     

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         lib,

     

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         pkgs,

     

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         utils,

     

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         ...

     

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       }:

     

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       let

     

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         # The scripted initrd contains some magic to add the prefix to the

     

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         # paths just in time, so we don't add it here.

     

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         sysrootPrefix = fs:

     

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           if config.boot.initrd.systemd.enable && fs.overlay.useStage1BaseDirectories && (utils.fsNeededForBoot fs) then

     

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         sysrootPrefix =

     

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           fs:

     

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           if

     

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             config.boot.initrd.systemd.enable

     

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             && fs.overlay.useStage1BaseDirectories

     

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             && (utils.fsNeededForBoot fs)

     

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           then

     

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             "/sysroot"

     

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           else

     

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             "";

     

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         # Returns a service that creates the required directories before the mount is

     

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         # created.

     

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         preMountService = _name: fs:

     

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         preMountService =

     

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           _name: fs:

     

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           let

     

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             prefix = sysrootPrefix fs;

     

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             upperdir = prefix + fs.overlay.upperdir;

     

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             workdir = prefix + fs.overlay.workdir;

     

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           in

     

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           lib.mkIf (fs.overlay.upperdir != null)

     

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             {

     

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               "rw-${escapedMountpoint}" = {

     

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                 requiredBy = [ mountUnit ];

     

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                 before = [ mountUnit ];

     

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                 unitConfig = {

     

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                   DefaultDependencies = false;

     

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                   RequiresMountsFor = "${upperdir} ${workdir}";

     

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                 };

     

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                 serviceConfig = {

     

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                   Type = "oneshot";

     

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                   ExecStart = "${pkgs.coreutils}/bin/mkdir -p -m 0755 ${upperdir} ${workdir}";

     

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       -
                 };

     

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           lib.mkIf (fs.overlay.upperdir != null) {

     

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             "rw-${escapedMountpoint}" = {

     

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               requiredBy = [ mountUnit ];

     

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               before = [ mountUnit ];

     

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               unitConfig = {

     

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                 DefaultDependencies = false;

     

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                 RequiresMountsFor = "${upperdir} ${workdir}";

     

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               };

     

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               serviceConfig = {

     

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                 Type = "oneshot";

     

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                 ExecStart = "${pkgs.coreutils}/bin/mkdir -p -m 0755 ${upperdir} ${workdir}";

     

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               };

     

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             };

     

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           };

     

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         overlayOpts = { config, ... }: {

     

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         overlayOpts =

     

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           {

     

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             config,

     

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             ...

     

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           }:

     

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           {

     

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             options.overlay = {

     

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               lowerdir = lib.mkOption {

     

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                 type = with lib.types; nullOr (nonEmptyListOf (either str pathInStore));

     

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                 default = null;

     

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                 description = ''

     

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                   The list of path(s) to the lowerdir(s).

     

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           options.overlay = {

     

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                   To create a writable overlay, you MUST provide an `upperdir` and a

     

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                   `workdir`.

     

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             lowerdir = lib.mkOption {

     

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               type = with lib.types; nullOr (nonEmptyListOf (either str pathInStore));

     

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               default = null;

     

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               description = ''

     

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                 The list of path(s) to the lowerdir(s).

     

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                   You can create a read-only overlay when you provide multiple (at

     

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                   least 2!) lowerdirs and neither an `upperdir` nor a `workdir`.

     

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                 '';

     

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               };

     

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                 To create a writable overlay, you MUST provide an `upperdir` and a

     

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                 `workdir`.

     

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               upperdir = lib.mkOption {

     

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                 type = lib.types.nullOr lib.types.str;

     

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                 default = null;

     

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                 description = ''

     

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                   The path to the upperdir.

     

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                 You can create a read-only overlay when you provide multiple (at

     

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                 least 2!) lowerdirs and neither an `upperdir` nor a `workdir`.

     

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               '';

     

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             };

     

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                   If this is null, a read-only overlay is created using the lowerdir.

     

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                   If the filesystem is `neededForBoot`, this will be prefixed with `/sysroot`,

     

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                   unless `useStage1BaseDirectories` is set to `true`.

     

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             upperdir = lib.mkOption {

     

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               type = lib.types.nullOr lib.types.str;

     

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               default = null;

     

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               description = ''

     

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                 The path to the upperdir.

     

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                   If you set this to some value you MUST also set `workdir`.

     

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                 '';

     

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               };

     

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                 If this is null, a read-only overlay is created using the lowerdir.

     

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               workdir = lib.mkOption {

     

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                 type = lib.types.nullOr lib.types.str;

     

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                 default = null;

     

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                 description = ''

     

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                   The path to the workdir.

     

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                 If the filesystem is `neededForBoot`, this will be prefixed with `/sysroot`,

     

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                 unless `useStage1BaseDirectories` is set to `true`.

     

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                   If the filesystem is `neededForBoot`, this will be prefixed with `/sysroot`,

     

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                   unless `useStage1BaseDirectories` is set to `true`.

     

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                 If you set this to some value you MUST also set `workdir`.

     

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               '';

     

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             };

     

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                   This MUST be set if you set `upperdir`.

     

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                 '';

     

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               };

     

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             workdir = lib.mkOption {

     

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               type = lib.types.nullOr lib.types.str;

     

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               default = null;

     

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               description = ''

     

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                 The path to the workdir.

     

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               useStage1BaseDirectories = lib.mkOption {

     

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                 type = lib.types.bool;

     

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                 default = true;

     

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                 description = ''

     

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                   If enabled, `lowerdir`, `upperdir` and `workdir` will be prefixed with `/sysroot`.

     

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                 If the filesystem is `neededForBoot`, this will be prefixed with `/sysroot`,

     

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                 unless `useStage1BaseDirectories` is set to `true`.

     

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                   Disabling this can be useful to create an overlay over directories which aren't on the real root.

     

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                 This MUST be set if you set `upperdir`.

     

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               '';

     

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                   Disabling this does not work with the scripted (i.e. non-systemd) initrd.

     

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                 '';

     

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               };

     

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             };

     

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             useStage1BaseDirectories = lib.mkOption {

     

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               type = lib.types.bool;

     

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               default = true;

     

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               description = ''

     

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                 If enabled, `lowerdir`, `upperdir` and `workdir` will be prefixed with `/sysroot`.

     

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             config = lib.mkIf (config.overlay.lowerdir != null) {

     

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               fsType = "overlay";

     

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               device = lib.mkDefault "overlay";

     

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               depends = map (x: "${x}") (

     

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                 config.overlay.lowerdir

     

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                 ++ lib.optionals (config.overlay.upperdir != null) [

     

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                   config.overlay.upperdir

     

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                   config.overlay.workdir

     

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                 ]

     

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               );

     

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                 Disabling this can be useful to create an overlay over directories which aren't on the real root.

     

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               options =

     

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                 let

     

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                   prefix = sysrootPrefix config;

     

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                 Disabling this does not work with the scripted (i.e. non-systemd) initrd.

     

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               '';

     

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                   lowerdir = map (s: prefix + s) config.overlay.lowerdir;

     

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                   upperdir = prefix + config.overlay.upperdir;

     

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                   workdir = prefix + config.overlay.workdir;

     

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                 in

     

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                 [

     

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                   "lowerdir=${lib.concatStringsSep ":" lowerdir}"

     

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                 ]

     

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                 ++ lib.optionals (config.overlay.upperdir != null) [

     

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                   "upperdir=${upperdir}"

     

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                   "workdir=${workdir}"

     

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                 ];

     

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             };

     

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           };

     

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           config = lib.mkIf (config.overlay.lowerdir != null) {

     

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             fsType = "overlay";

     

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             device = lib.mkDefault "overlay";

     

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             depends = map (x: "${x}") (config.overlay.lowerdir ++ lib.optionals (config.overlay.upperdir != null) [

     

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               config.overlay.upperdir

     

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               config.overlay.workdir

     

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             ]);

     

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             options =

     

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               let

     

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                 prefix = sysrootPrefix config;

     

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                 lowerdir = map (s: prefix + s) config.overlay.lowerdir;

     

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                 upperdir = prefix + config.overlay.upperdir;

     

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                 workdir = prefix + config.overlay.workdir;

     

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               in

     

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               [

     

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                 "lowerdir=${lib.concatStringsSep ":" lowerdir}"

     

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               ] ++ lib.optionals (config.overlay.upperdir != null) [

     

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                 "upperdir=${upperdir}"

     

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                 "workdir=${workdir}"

     

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               ];

     

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           };

     

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         };

     

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       in

     

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       {