Can't pass symlinks as flakerefs

[anirudhb]

Looks like this was changed in #5771, specifically here:
99d617b#diff-bf478d9714839229d3d706a7dcf96aebe2d6193e67cf06f06f440279a53ea36fL114-L116

Even if this was intended, it would be nice to have symlink flakerefs still working as CLI arguments (my config is a symlinked dir, and I haven't had issues building it until now.)

[virchau13]

I think the reason why this was changed was to forbid symlinks being used in flake inputs. (Does this break hermetic evaluation or something?) It would still be nice to use symlinks when directly invoking the Nix tools, though.

[alex-robbins]

I don't think changing when symlinks are allowed was an intentional effect of that change. It was to solve #5387 where absolute paths were sometimes not allowed (for reasons explained by this comment).

nixos-rebuild has the following in the man page for --flake, and it still works even when /etc/nixos is a symlink:

It defaults to the directory containing the target of the symlink /etc/nixos/flake.nix, if it exists.

So now, when /etc/nixos is a symlink, nixos-rebuild switch works but nixos-rebuild switch --flake /etc/nixos does not.

[SomeoneSerge]

Yup, just ran into this with /etc/nixos

[pinpox]

Is there any way to make this work for flakes in other directories? I have my flake in a different directory and was using nixos-rebiuld switch --flake /path/to/mydir#myhost which is not possible if /path/to/mydir is replaced by a symlink.

My workaround is:

                                  --flake "$(readlink -f symlink-to-mydir)#myhost"

Which works, but is a bit hacky