How to include/configure `early-init.el` ?

[bhankas]

I'm a long time nix-doom-emacs-unstraightened user on top of emacs-overlay. Currently doomemacs takes care of a lot of stuff, but after having to work around doom for the umpteenth time I'm finally building my emacs config from scratch.

I want my Emacs to continue to be built by Nix using emacs-overlay. I can see there is support for manually specifying emacs.el (init.el). However, I do not see any way to specify early-init.el. I'd like to add fair amount of startup optimizations in this file, and I'd like this file to be immutably part of Emacs closure built by Nix.

There is kind of an example of this, but I'd prefer an option built into emacs-overlay. Is there any way to do that or did I miss something obvious?

[jian-lin]

early-init.el, unlike init.el, cannot be "packaged" as a nix package. (Well, init.el also cannot. We workaround that by using init.el as a default.el). This is a limitation of Emacs, not nix. So earyly-init.el is "not supported" by emacs.pkgs.withPackages and its wrappers like emacsWithPackagesFromUsePackage and home-manager's programs.emacs.

To manage early-init.el using nix, you can use things that manage files directly, such as systemd.tmpfiles or home-manager's home.files/xdg.configFile.

[jian-lin]

The first step is done in NixOS/nixpkgs#536492.

When that is merged, this issue can be used to track the status of supporting early-default in emacsWithPackagesFromUsePackage.