Symlinks created via the home-manager module are broken

[Janrupf]

Adding the following configuration creates a broken symlink persistent in /home/janrupf:

home.persistence."/persistent/home/janrupf" = {
  directories = [
    { directory = "persistent"; method = "symlink"; }
  ];
}

Inspecting:

$ readlink persistent
/nix/store/vlidns7s3sp46bkw65nmr8wj7lbhvkvx-home-manager-files/persistent
$ readlink /nix/store/vlidns7s3sp46bkw65nmr8wj7lbhvkvx-home-manager-files/persistent
/nix/store/iwbbjrdnqrffd8bjv4yi5yvanhj6w8f0-persistent-home-janrupf-persistent
$ readlink /nix/store/iwbbjrdnqrffd8bjv4yi5yvanhj6w8f0-persistent-home-janrupf-persistent
/persistent/home/janrupf/persistent

So the symlink does point to the correct location afterall - the issue is, that location is never created.
The creation is supposed to happen here:

impermanence/home-manager.nix

Lines 451 to 461 in a33ef10

	createTargetFileDirectories =
	dag.entryBefore
	[ "writeBoundary" ]
	(concatMapStrings
	(persistentStorageName:
	concatMapStrings
	(targetFilePath: ''
	mkdir -p ${escapeShellArg (concatPaths [ cfg.${persistentStorageName}.persistentStoragePath (dirOf targetFilePath) ])}
	'')
	(map getDirPath (cfg.${persistentStorageName}.files ++ (filter isSymlink cfg.${persistentStorageName}.directories))))
	persistentStorageNames);

Inspecting the flake output reveals that the command added to home.activation.createTargetFileDirectories is mkdir -p /persistent/home/janrupf/. - notice the dot at the end. I think this is caused by the dirOf call on line 458.

[Janrupf]

Temporary fix:

  home.activation.createTargetFileDirectoriesFixup =
  let
    isSymlink = entry: (!lib.isString entry) && (entry.method == "symlink");
    entryPath = entry: if lib.isString entry then entry else entry.directory;

    cfg = config.home.persistence;

    persistenceRoots = lib.attrNames cfg;
    mkdirPersistentLocations = map (root:
      let
        persistentDiskPath = cfg.${root}.persistentStoragePath;
        persistentDirectories = 
          # Collect all directories which are symlinks
          (map entryPath (lib.filter isSymlink cfg.${root}.directories)) ++
          # And all directories of files
          (map lib.dirOf (map entryPath (cfg.${root}.files)));
        
        completePaths = map (path: lib.path.append (/. + root) path) persistentDirectories;
        mkdirCommands = lib.concatMapStrings (completePath: "run mkdir -p ${lib.escapeShellArg completePath}\n") completePaths;
      in ''
        # mkdir's for ${root}

        ${mkdirCommands}
      ''
    ) persistenceRoots;
  in
    config.lib.dag.entryBetween [ "writeBoundary" ] [ "createTargetFileDirectories" ] (
      lib.concatMapStrings (cmds: "${cmds}\n") mkdirPersistentLocations
    );

This should create all directories as intended when put into the home-manager configuration.

[Schwanzskala]

I've also ran into this problem.
The temporary fix works, although for me with one minor modification; I had to change lib.dirOf to just dirOf.

[bphenriques]

I think I am running a similar issue. All my directories are working. If I add the following:

  home.persistence."${config.custom.impermanence.dataLocation}".directories = [
    { directory = ".dotfiles"; method = "symlink"; } # Testing something...
  ];

The chain leads to nowhere, leading to "No such file or directory". I suspect it is due to the . in the beginning.

It does work with .steam but that folder isn't using symlinks.

[Janrupf]

Its just generally broken with the symlink method because there's the bug in the logic mentioned above, doesn't matter whether the name has a leading dot or not