Derivation Metadata

A derivation’s metadata gives information regarding the application and its target android environment.

An example of a proper metadata field for an android application is as follows:

meta = {
  description = "An open source flashcard app for spaced repetition learning";
  homepage = "https://mihon.app";
  license = lib.licenses.asl20;
  maintainers = with lib.maintainers; [ osbm ]; # from nixpkgs maintainers list
  android = {
    minSdk = 26;
    targetSdk = 36;
    applicationId = "app.mihon";
    abis = [
      "armeabi-v7a"
      "arm64-v8a"
      "x86"
      "x86_64"
    ];
  };
};

Homepage

The homepage URL of the application. If it does not have a homepage, you can use the repository URL.

License

The license under which the application is distributed. You can use licenses from lib.licenses in nixpkgs.

Maintainers

A list of maintainers for the derivation. You can use maintainers from lib.maintainers in nixpkgs.

TODO: what happens if the maintainer is not in the nixpkgs maintainers list?

Android

Metadata specific to the Android application, including SDK versions, application ID, and supported ABIs.

minSdk

The minimum SDK version required to run the application.

targetSdk

The target SDK version for which the application is optimized.

applicationId

The unique application ID (package name) for the Android application.

abis

A list of supported ABIs (Application Binary Interfaces) for the application. Common values include:

armeabi-v7a
arm64-v8a
x86
x86_64

An APK is a self-contained file: it must not reference any Nix store path. This is not a convention but a build-time guarantee. Every package under apks/ is given allowedReferences = [ ] (in lib/default.nix; the gradle2nix builder sets it itself), so Nix refuses to register an output that refers to the store:

error: output '/nix/store/…-fossify-calculator-1.4.0.apk' is not allowed to refer to the following paths:

Nothing has to be added to a package for this, and there is no separate CI step: any nix build of an app, locally or in CI, is the check. If it ever triggers, look for a store path leaking into the apk (a hard-coded tool path in a generated file, a copied symlink, …). Avoid buildInputs in APK packages — evaluation warns about them — and put tools in nativeBuildInputs.

nixapks