Help with replacing package with self compiled version

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1

Hello

I have folowing parts in my /etc/nixos/configuration.nix:

systemd.services.hostapd.wantedBy= [ "multi-user.target" ];
  systemd.services.hostapd.after = [ "sys-subsystem-net-devices-wlp4s0.device" "nat.service" "bind>

  services.hostapd = {

Unfortunatelly this hostapd version seems not to support wifi 6, hence I complied my own version with “CONFIG_IEEE80211AX=y”.
For that I have created in /root a folder structure:

/root/nixos/private-packages
├── default.nix
└── pkgs
    └── hostapd
        └── default.nix

/root/nixos/private-packages/default.nix:

{ system ? builtins.currentSystem }:                                                   
                                                                                   
let                                                                                    
   pkgs = import <nixpkgs> { inherit system; };                                         
                                                                                   
   callPackage = pkgs.lib.callPackageWith (pkgs // self);                               
                                                                                   
   self = {                                                                             
      hostapd = callPackage ./pkgs/hostapd { };                                            
   };                                                                                   
   in self

/root/nixos/private-packages/pkgs/hostapd/default.nix:

{
lib
, stdenv
, fetchurl
, pkg-config
, libnl
, openssl 
}:

stdenv.mkDerivation {
  name = "hostapd";

  src = fetchurl {
    url = "https://w1.fi/cgit/hostap/snapshot/hostap_2_10.tar.gz";
    sha256 = "f39df26eb76757d8ab3a27178545e2ead33ce32daddef771cd38c35893e8c392";
  };
    nativeBuildInputs = [ pkg-config ];
  buildInputs = [ libnl openssl ];

  extraConfig = ''
    CONFIG_DRIVER_WIRED=y
    CONFIG_LIBNL32=y
    CONFIG_EAP_SIM=y
    CONFIG_EAP_AKA=y
    CONFIG_EAP_AKA_PRIME=y
    CONFIG_EAP_PAX=y
    CONFIG_EAP_PWD=y
    CONFIG_EAP_SAKE=y
    CONFIG_EAP_GPSK=y
    CONFIG_EAP_GPSK_SHA256=y
    CONFIG_EAP_FAST=y
    CONFIG_EAP_IKEV2=y
    CONFIG_EAP_TNC=y
    CONFIG_EAP_EKE=y
    CONFIG_RADIUS_SERVER=y
    CONFIG_IEEE80211R=y
    CONFIG_IEEE80211N=y
    CONFIG_IEEE80211AC=y
    CONFIG_IEEE80211AX=y
    CONFIG_FULL_DYNAMIC_VLAN=y
    CONFIG_VLAN_NETLINK=y
    CONFIG_TLS=openssl
    CONFIG_TLSV11=y
    CONFIG_TLSV12=y
    CONFIG_INTERNETWORKING=y
    CONFIG_HS20=y
    CONFIG_ACS=y
    CONFIG_GETRANDOM=y
    CONFIG_SAE=y
  '';

  postPatch = ''
    substituteInPlace hostapd/Makefile --replace /usr/local $out
  '';

  configurePhase = ''
    runHook preConfigure
    cd hostapd
    cp -v defconfig .config
    echo "$extraConfig" >> .config
    export NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE $(pkg-config --cflags libnl-${lib.versions.major libnl.version}.0)"
    runHook postConfigure
  '';

  preInstall = ''
    mkdir -p $out/bin
  '';

  meta = with lib; {
    homepage = "https://w1.fi/cgit/hostap/";
    description = "A  wifi access point tool";
    license = licenses.bsd3;
    maintainers = with maintainers; [ Jouni Malinen ];
    platforms = platforms.linux;
  };
}

I can compile and install the package with:

export NIX_PATH=custompkgs=/root/nixos/private-packages/default.nix:$NIX_PATH
nix-env -f '<custompkgs>' -iA hostapd

But how could I integrate it in /etc/nixos/configuration.nix that the default hostapd service will be overwritten with the self compiled version. I’m new to nixos, any help would be highly appriciated.

Regards Sven

2

Hello,

What you are probably looking for is the overlay mechanism.

Here is the documentation in the nixpkgs manual and here is a better (imo) documentation in the wiki.

Curiously, there is little mention of overlays in the nixos documentation, I understand that is not strictly speaking a nixos mechanism but as a way to change packages in your system, we might want to link to the corresponding nixpkgs chapter.

3

Thx a lot for quick respond. It is a lot of information, so it’s still difficult for a newbe, but I think I got it:
I added to my /etc/nixos/configuration.nix

  nixpkgs.overlays = [ (self: super:
  {
    hostapd = super.callPackage /root/nixos/private-packages/pkgs/hostapd/default.nix {};
  }
  ) ];

It is for sure not the most elegant solution, but it seems to work for now.

Regards Sven