I use this:

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
    home-manager.url = "github:nix-community/home-manager/release-25.05";
    nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixpkgs-unfree.url = "github:numtide/nixpkgs-unfree";
    nixpkgs-unfree.inputs.nixpkgs.follows = "nixpkgs-unstable";
  };

  outputs = {
    self,
    nixpkgs,
    home-manager,
    nixpkgs-unstable,
    ...
  } @ attrs: {
    nixosConfigurations.laptopname = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      specialArgs = attrs;
      modules = [
        ./configuration.nix
      ];
    };
  };
}

and my configuration.nix includes everything for me

Howdy all! I've got a pending PR that I wanna reduce back-and-forth on, so have been trying to do some local testing to ensure my eyes are crossed.

My end-goal is to have locally cloned NixOS/nixpkgs under a name-space like git-nixpkgs so I can pick-and-choose bits I wanna test. But been hitting some skill issues I have x-)

Got me the source successfully;

mkdir -vp ~/git/hub/NixOS &&
  pushd "${_}" &&
  git clone --depth=1 git@github.com:NixOS/nixpkgs.git

Did edits and they work when doing import, but now I wanna use the local repo as an inputs to my system flake.nix file, ex;

/etc/nixos/flake.nix (snip)

{
  inputs = {
    # ...
    git-nixpkgs = {
      type = "path";
      path = "/home/s0ands0/git/hub/NixOS/nixpkgs";
    };
  };

  outputs = { self, ... }@attrs: {
    nixosConfigurations.nixos = nixpkgs.lib.nixosSystem = {
      system = "x86_64-linux";
      specialArgs = attrs;
      modules = [
        ./configuration.nix
        # ...
      ];
    };
  };
}

... But this is where things fall apart;

/etc/nixos/configuration.nix

{ git-nix, ... }:
{
  # ...
  services.dictd = {
    enable = true;
    DBs = with git-nixpkgs.pkgs.dictdDBs; [
      gcide
    ];
  };
}

I'm popping errors of pkgs attribute doesn't exist on git-nixpkgs :-(

This be less than fantastic as REPL shows the attribute available if I start it with something like, nix repl --expr 'import /home/s0ands0/git/hub/NixOS/nixpkgs {}', so I feel like I'm missing some key differences between classy flavored Nix imports vs the new fancy flakes?

Howdy all! I've got a pending PR that I wanna reduce back-and-forth on, so have been trying to do some local testing to ensure my eyes are crossed.

My end-goal is to have locally cloned NixOS/nixpkgs under a name-space like git-nixpkgs so I can pick-and-choose bits I wanna test. But been hitting some skill issues I have x-)

Got me the source successfully;

mkdir -vp ~/git/hub/NixOS &&
  pushd "${_}" &&
  git clone --depth=1 git@github.com:NixOS/nixpkgs.git

Did edits and they work when doing import, but now I wanna use the local repo as an inputs to my system flake.nix file, ex;

/etc/nixos/flake.nix (snip)

{
  inputs = {
    # ...
    git-nixpkgs = {
      type = "path";
      path = "/home/s0ands0/git/hub/NixOS/nixpkgs";
    };
  };

  outputs = { self, ... }@attrs: {
    nixosConfigurations.nixos = nixpkgs.lib.nixosSystem = {
      system = "x86_64-linux";
      specialArgs = attrs;
      modules = [
        ./configuration.nix
        # ...
      ];
    };
  };
}

... But this is where things fall apart;

/etc/nixos/configuration.nix

{ git-nixpkgs, ... }:
{
  # ...
  services.dictd = {
    enable = true;
    DBs = with git-nixpkgs.pkgs.dictdDBs; [
      gcide
    ];
  };
}

I'm popping errors of pkgs attribute doesn't exist on git-nixpkgs :-(

This be less than fantastic as REPL shows the attribute available if I start it with something like, nix repl --expr 'import /home/s0ands0/git/hub/NixOS/nixpkgs {}', so I feel like I'm missing some key differences between classy flavored Nix imports vs the new fancy flakes?

Howdy all! I've got a pending PR that I wanna reduce back-and-forth on, so have been trying to do some local testing to ensure my eyes are crossed.

My end-goal is to have locally cloned NixOS/nixpkgs under a name-space like git-nixpkgs so I can pick-and-choose bits I wanna test. But been hitting some skill issues I have x-)

Got me the source successfully;

mkdir -vp ~/git/hub/NixOS &&
  pushd "${_}" &&
  git clone --depth=1 git@github.com:NixOS/nixpkgs.git

Did edits and they work when doing import, but now I wanna use the local repo as an inputs to my system flake.nix file, ex;

/etc/nixos/flake.nix (snip)

{
  inputs = {
    # ...
    git-nixpkgs = {
      type = "path";
      path = "/home/s0ands0/git/hub/NixOS/nixpkgs";
    };
  };

  outputs = { self, nixpkgs, ... }@attrs: {
    nixosConfigurations.nixos = nixpkgs.lib.nixosSystem = {
      system = "x86_64-linux";
      specialArgs = attrs;
      modules = [
        ./configuration.nix
        # ...
      ];
    };
  };
}

... But this is where things fall apart;

/etc/nixos/configuration.nix

{ git-nixpkgs, ... }:
{
  # ...
  services.dictd = {
    enable = true;
    DBs = with git-nixpkgs.pkgs.dictdDBs; [
      gcide
    ];
  };
}

I'm popping errors of pkgs attribute doesn't exist on git-nixpkgs :-(

This be less than fantastic as REPL shows the attribute available if I start it with something like, nix repl --expr 'import /home/s0ands0/git/hub/NixOS/nixpkgs {}', so I feel like I'm missing some key differences between classy flavored Nix imports vs the new fancy flakes?

Howdy all! I've got a pending PR that I wanna reduce back-and-forth on, so have been trying to do some local testing to ensure my eyes are crossed.

My end-goal is to have locally cloned NixOS/nixpkgs under a name-space like git-nixpkgs so I can pick-and-choose bits I wanna test. But been hitting some skill issues I have x-)

Got me the source successfully;

mkdir -vp ~/git/hub/NixOS &&
  pushd "${_}" &&
  git clone --depth=1 git@github.com:NixOS/nixpkgs.git

Did edits and they work when doing import, but now I wanna use the local repo as an inputs to my system flake.nix file, ex;

/etc/nixos/flake.nix (snip)

{
  inputs = {
    # ...
    git-nixpkgs = {
      type = "path";
      path = "/home/s0ands0/git/hub/NixOS/nixpkgs";
    };
  };

  outputs = { self, nixpkgs, ... }@attrs: {
    nixosConfigurations.nixos = nixpkgs.lib.nixosSystem = {
      system = "x86_64-linux";
      specialArgs = attrs;
      modules = [
        ./configuration.nix
        # ...
      ];
    };
  };
}

... But this is where things fall apart;

/etc/nixos/configuration.nix

{ git-nixpkgs, ... }:
{
  # ...
  services.dictd = {
    enable = true;
    DBs = with git-nixpkgs.pkgs.dictdDBs; [
      gcide
    ];
  };
}

I'm popping errors of pkgs attribute doesn't exist on git-nixpkgs :-(

This be less than fantastic as REPL shows the attribute available if I start it with something like, nix repl --expr 'import /home/s0ands0/git/hub/NixOS/nixpkgs {}', so I feel like I'm missing some key differences between classy flavored Nix imports vs the new fancy flakes?

Edit: here's what I found works, if willing to rebuild with --impure flag;

/etc/nixos/configuration.nix

{ ... }:
let
  git-nixpkgs = import /home/s0ands0/git/hub/NixOS/nixpkgs;
in
{
  # ...
  services.dictd = {
    enable = true;
    DBs = with git-nixpkgs.pkgs.dictdDBs; [
      gcide
    ];
  };
}

... feels like I really am missing something fundamental about Flakes 🤷

Howdy all! I've got a pending PR that I wanna reduce back-and-forth on, so have been trying to do some local testing to ensure my eyes are crossed.

My end-goal is to have locally cloned NixOS/nixpkgs under a name-space like git-nixpkgs so I can pick-and-choose bits I wanna test. But been hitting some skill issues I have x-)

Got me the source successfully;

mkdir -vp ~/git/hub/NixOS &&
  pushd "${_}" &&
  git clone --depth=1 git@github.com:NixOS/nixpkgs.git

Did edits and they work when doing import, but now I wanna use the local repo as an inputs to my system flake.nix file, ex;

/etc/nixos/flake.nix (snip)

{
  inputs = {
    # ...
    git-nixpkgs = {
      type = "path";
      path = "/home/s0ands0/git/hub/NixOS/nixpkgs";
    };
  };

  outputs = { self, nixpkgs, ... }@attrs: {
    nixosConfigurations.nixos = nixpkgs.lib.nixosSystem = {
      system = "x86_64-linux";
      specialArgs = attrs;
      modules = [
        ./configuration.nix
        # ...
      ];
    };
  };
}

... But this is where things fall apart;

/etc/nixos/configuration.nix

{ git-nixpkgs, ... }:
{
  # ...
  services.dictd = {
    enable = true;
    DBs = with git-nixpkgs.pkgs.dictdDBs; [
      gcide
    ];
  };
}

I'm popping errors of pkgs attribute doesn't exist on git-nixpkgs :-(

This be less than fantastic as REPL shows the attribute available if I start it with something like, nix repl --expr 'import /home/s0ands0/git/hub/NixOS/nixpkgs {}', so I feel like I'm missing some key differences between classy flavored Nix imports vs the new fancy flakes?

Edit: here's what I found works, if willing to rebuild with --impure flag;

/etc/nixos/configuration.nix

{ ... }:
let
  git-nixpkgs = import /home/s0ands0/git/hub/NixOS/nixpkgs { };
in
{
  # ...
  services.dictd = {
    enable = true;
    DBs = with git-nixpkgs.pkgs.dictdDBs; [
      gcide
    ];
  };
}

... feels like I really am missing something fundamental about Flakes 🤷

Tragically the same story, but with error: attribute 'legacyPackages' missing now

... I added a lib.warn (builtins.toString (builtins.attrNames git-nixpkgs)) between function args and body, and noticed nothing's printed when building with Flake inputs but a whole lotta stuff gets dumped if I go the import route