I’ve been messing around with nix flakes to configure my NixOS system and to put the final touches on I wanted to write an overlay of Neovim with the plugins and everything configured with Lua and then use this overlay to install neovim-qt. After reading various docs on Overlays, I get the fundamentals but I don’t get where to look to find a list of all the configurable options that an overlay provides? Typically I can look in the home-mananger nix decleration of a package for the options exposed or nixpkgs for the options in configuration.nix. Any help that will dive deeper into overlays or where to find their options would be greatly appreciated!
Inside of this example would the sets that are changeable inside of .override like bar for example be the definitions made within the .nix file for a respective package? I’m trying to understand how I know what can be overridden.
You can override derivation inputs and derivation attributes. Let’s take for example the nano editor.
You can enable tidy support by overriding the
enableTidyinput like so:(final: prev: { nano = prev.nano.override { enableTidy = true; }; })You can also override build steps, eg. if you want to apply an upstream patch because you don’t want to wait for the next release version, you’d do it like this.
(final: prev: { nano = prev.nano.overrideAttrs ( old: { patches = (old.patches or [] ) ++ [ ./filename.patch ]; }); })Now the thing about overlays is this: if you change a package in an overlay, all packages depending on that package, either directly or indirectly, will pull in that modified version, which is an extremely powerful tool as you can probably imagine.
It all makes sense now!