Replace Modules
Modules that are imported can also be disabled. The option
declarations and config implementation 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 http://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." ];
};
}