Create Nix Package

Create a new Nix package from source code, a binary, or a script.

Parameter Handling

If parameters are missing from $ARGUMENTS, use mcp_question to gather them:

mcp_question({
  questions: [
    {
      question: "What should the package be named?",
      header: "Name",
      options: [
        { label: "Enter name...", description: "e.g., myapp (lowercase, hyphens OK)" }
      ]
    },
    {
      question: "Where does the source code come from?",
      header: "Source",
      options: [
        { label: "GitHub (Recommended)", description: "Public GitHub repository" },
        { label: "Git repository", description: "Any git repo (including private)" },
        { label: "URL/archive", description: "Direct download URL" },
        { label: "Local", description: "Files in package directory" }
      ]
    },
    {
      question: "What language/build system does it use?",
      header: "Build",
      options: [
        { label: "Go module", description: "Go with go.mod" },
        { label: "Rust/Cargo", description: "Rust with Cargo.toml" },
        { label: "Python", description: "Python package" },
        { label: "Shell script", description: "Wrap shell script" },
        { label: "Binary", description: "Prebuilt binary" }
      ]
    }
  ]
})

Expected $ARGUMENTS format: <packagename> <sourcetype> <build_system>

• Example: myapp github go
• Example: mytool local shell

Package Directory Structure

packages/<package-name>/
├── default.nix      # Package definition
└── README.md        # Documentation (optional but recommended)

Steps

1. Create package directory

mkdir -p packages/<package-name>

2. Create default.nix

Choose the appropriate template based on source type.

3. Build and test

nix build .#<package-name>
./result/bin/<program> --version

4. Document in README.md

5. Update packages/README.md with entry

Templates

Shell Script Package

{ lib, stdenv, makeWrapper, bash, coreutils }:

stdenv.mkDerivation rec {
  pname = "script-name";
  version = "1.0.0";

  src = ./.;

  nativeBuildInputs = [ makeWrapper ];
  buildInputs = [ bash ];

  dontBuild = true;

  installPhase = ''
    runHook preInstall
    mkdir -p $out/bin
    cp script.sh $out/bin/${pname}
    chmod +x $out/bin/${pname}
    wrapProgram $out/bin/${pname} \
      --prefix PATH : ${lib.makeBinPath [ coreutils ]}
    runHook postInstall
  '';

  meta = with lib; {
    description = "Description";
    homepage = "https://github.com/user/repo";
    license = licenses.mit;
    platforms = platforms.unix;
  };
}

Rust Package

{ lib, rustPlatform, fetchFromGitHub, pkg-config, openssl }:

rustPlatform.buildRustPackage rec {
  pname = "package-name";
  version = "1.0.0";

  src = fetchFromGitHub {
    owner = "user";
    repo = "repo";
    rev = "v${version}";
    hash = "sha256-AAAA...";
  };

  cargoHash = "sha256-BBBB...";

  nativeBuildInputs = [ pkg-config ];
  buildInputs = [ openssl ];

  meta = with lib; {
    description = "Description";
    homepage = "https://github.com/user/repo";
    license = licenses.mit;
    mainProgram = "package-name";
  };
}

Python Package

{ lib, python3Packages, fetchFromGitHub }:

python3Packages.buildPythonPackage rec {
  pname = "package-name";
  version = "1.0.0";
  format = "pyproject";

  src = fetchFromGitHub {
    owner = "user";
    repo = "repo";
    rev = "v${version}";
    hash = "sha256-AAAA...";
  };

  nativeBuildInputs = with python3Packages; [ setuptools wheel ];
  propagatedBuildInputs = with python3Packages; [ requests click ];

  pythonImportsCheck = [ "package_name" ];

  meta = with lib; {
    description = "Description";
    homepage = "https://github.com/user/repo";
    license = licenses.mit;
  };
}

Go Module

{ lib, buildGoModule, fetchFromGitHub }:

buildGoModule rec {
  pname = "package-name";
  version = "1.0.0";

  src = fetchFromGitHub {
    owner = "user";
    repo = "repo";
    rev = "v${version}";
    hash = "sha256-AAAA...";
  };

  vendorHash = "sha256-BBBB...";

  meta = with lib; {
    description = "Description";
    homepage = "https://github.com/user/repo";
    license = licenses.mit;
    mainProgram = "package-name";
  };
}

Getting Hashes

# Get hash from build error (use lib.fakeHash first)
nix build .#package-name 2>&1 | grep "got:" | awk '{print $2}'

# Or use nix-prefetch
nix-prefetch-github user repo --rev v1.0.0

Best Practices

• Always use fixed versions (never "latest")
• Use proper hash formats (sha256)
• Pin all dependencies explicitly
• Use dontBuild = true for scripts
• Add mainProgram for primary executable
• Document in README.md

Example

/create-nix-package myapp git rust