create dummy serial ports for the systemd service

nix/packages/air-quality-monitor.nix

@@ -0,0 +1,63 @@
+{
+  self,
+  lib,
+  python3Packages,
+  makeWrapper,
+  python3,
+  ...
+}: let
+  pname = "pi_air_quality_monitor";
+  version = "0.0.1";
+in
+  python3Packages.buildPythonApplication {
+    inherit pname version;
+    format = "other";
+
+    src = self + /src;
+
+    pythonPath = with python3Packages; [
+      pyserial
+      flask
+      redis
+      ipython
+      apscheduler
+      flask-cors
+      (
+        buildPythonPackage rec {
+          pname = "python-aqi";
+          version = "0.6.1";
+          src = fetchPypi {
+            inherit pname version;
+            hash = "sha256-FBoDoP7UiIDchwbKV7A/MPqRq2DpMwR0v5yaj7m5YCA=";
+          };
+        }
+      )
+    ];
+
+    nativeBuildInputs = [makeWrapper];
+    installFlags = ["prefix=$(out/bin)"];
+
+    postUnpack = ''
+      mkdir -p $out/bin
+      cp -rvf $src/* $out
+    '';
+
+    preFixup = ''
+      buildPythonPath "$pythonPath"
+      gappsWrapperArgs+=(
+        --prefix PYTHONPATH : "$program_PYTHONPATH"
+      )
+      makeWrapper ${lib.getExe python3} $out/bin/${pname} \
+          --add-flags $out/app.py \
+          --prefix PYTHONPATH : "$program_PYTHONPATH" \
+          --chdir $out/bin
+    '';
+
+    meta = {
+      description = "An air quality monitoring service with a Raspberry Pi and a SDS011 sensor. ";
+      homepage = "https://github.com/rydercalmdown/pi_air_quality_monitor";
+      mainProgram = pname;
+      platforms = ["aarch64-linux" "x86_64-linux"];
+      maintainers = with lib.maintainers; [NotAShelf];
+    };
+  }

nix/packages/dummy-serial.nix

@@ -0,0 +1,30 @@
+{
+  stdenv,
+  fetchFromGitHub,
+  ...
+}:
+stdenv.mkDerivation {
+  pname = "dummy-serial";
+  version = "0.1.0";
+
+  src = fetchFromGitHub {
+    owner = "notashelf";
+    repo = "dummy-serial";
+    rev = "v0.1.0";
+    hash = "sha256-+zXA5Ko8ikgkmkm1eyx2VMQQjp61osSpq4K+d9WEqq8=";
+  };
+
+  makeFlags = ["TARGET=main"];
+
+  installPhase = ''
+    runHook preInstall
+    mkdir -p $out/bin
+    cp -rvf main $out/bin/dummy-serial
+    runHook postInstall
+  '';
+
+  meta = {
+    description = "Create dummy serial ports through PseudoTTYs";
+    mainProgram = "dummy-serial";
+  };
+}