Nix Composable Derivation Options

Question

I'm trying to understand what options are available for me in my configuration.nix for particular programs, by searching the pkgs sub-folder of nixpkgs's source tree, picking out the module's definitions to understand the available options. However, I'm running into a troublesome case for PHP - it's a special derivation, a composable derivation. I'm not able to see what options I have available with PHP - something that would be tremendously helpful for enabling special modules like mcrypt, gd, etc. Any help with this would be greatly appreciated!

Answer 1

It took me a while to figure this out but the right way to use composeDerivation for setting the php package build features is this:

  # config.nix   {    packageOverrides = pkgs: rec {       php = pkgs.php.merge {         cfg = {           imapSupport = false;           intlSupport = false;           fpmSupport = false;         };       };    };   } 

This overrides the default values in cfg specified in php/default.nix (imapSupport, intlSupport and fpmSupport get turned off). You can either place that file in ~/.nixpkgs/config.nix to be active system-wide or use it in another nix file like so to customize the global nixpkgs:

pkgs = import <nixpkgs> { config = (import ./config.nix);  };