Replace Modules Modules that are imported can also be disabled. The option declarations, config implementation and the imports of a disabled module will be ignored, allowing another to take it's place. This can be used to import a set of modules from another channel while keeping the rest of the system on a stable release. disabledModules is a top level attribute like imports, options and config. It contains a list of modules that will be disabled. This can either be the full path to the module or a string with the filename relative to the modules path (eg. <nixpkgs/nixos/modules> for nixos). This example will replace the existing postgresql module with the version defined in the nixos-unstable channel while keeping the rest of the modules and packages from the original nixos channel. This only overrides the module definition, this won't use postgresql from nixos-unstable unless explicitly configured to do so. { config, lib, pkgs, ... }: { disabledModules = [ "services/databases/postgresql.nix" ]; imports = [ # Use postgresql service from nixos-unstable channel. # sudo nix-channel --add https://nixos.org/channels/nixos-unstable nixos-unstable <nixos-unstable/nixos/modules/services/databases/postgresql.nix> ]; services.postgresql.enable = true; } This example shows how to define a custom module as a replacement for an existing module. Importing this module will disable the original module without having to know it's implementation details. { config, lib, pkgs, ... }: with lib; let cfg = config.programs.man; in { disabledModules = [ "services/programs/man.nix" ]; options = { programs.man.enable = mkOption { type = types.bool; default = true; description = "Whether to enable manual pages."; }; }; config = mkIf cfg.enabled { warnings = [ "disabled manpages for production deployments." ]; }; }