nix: add Python packaging with uv2nix

Add uv2nix to build Python packages from uv.lock. This creates a fully Nix-managed Python environment with the Rust bindings injected via overlay. Changes: - Add pyproject-nix, uv2nix, and pyproject-build-systems flake inputs - Create python/parts.nix with overlays to inject Nix-built Rust wheel - Export packages.exo on macOS (wraps exo/exo-master/exo-worker with dashboard) - Add checks.lint (ruff, all platforms) and checks.pytest (macOS only) - Simplify CI typecheck job using nicknovitski/nix-develop action - Delete .github/actions/typecheck composite action (no longer needed) - Add no-build-package for MLX packages in pyproject.toml (use wheels) The Python build is currently macOS-only since MLX requires Metal. Linux support will be added once the pyproject dependencies are simplified. Test plan: - Run `nix flake check` on macOS to verify pytest and lint pass - Build exo package on macOS: `nix build .#exo` - Verify CI pipeline passes with simplified typecheck job
2026-02-18 23:06:23 -05:00 · 2026-01-15 18:37:02 +00:00
parent b1e88a3d06
commit e4c6a7dbb4
5 changed files with 190 additions and 89 deletions
--- a/python/parts.nix
+++ b/python/parts.nix
@@ -0,0 +1,93 @@
+{ inputs, ... }:
+{
+  perSystem =
+    { config, self', pkgs, lib, system, ... }:
+    let
+      # Load workspace from uv.lock
+      workspace = inputs.uv2nix.lib.workspace.loadWorkspace {
+        workspaceRoot = inputs.self;
+      };
+
+      # Create overlay from workspace
+      # Use wheels from PyPI for most packages; we override mlx with our pure Nix Metal build
+      overlay = workspace.mkPyprojectOverlay { sourcePreference = "wheel"; };
+
+      # Override overlay to inject Nix-built components
+      exoOverlay = final: prev: {
+        # Replace workspace exo_pyo3_bindings with Nix-built wheel
+        exo-pyo3-bindings = pkgs.stdenv.mkDerivation {
+          pname = "exo-pyo3-bindings";
+          version = "0.1.0";
+          src = self'.packages.exo_pyo3_bindings;
+          # Install from pre-built wheel
+          nativeBuildInputs = [ final.pyprojectWheelHook ];
+          dontStrip = true;
+        };
+      };
+
+      python = pkgs.python313;
+
+      # Overlay to provide build systems and custom packages
+      buildSystemsOverlay = final: prev: {
+        # Use our pure Nix-built MLX with Metal support
+        mlx = self'.packages.mlx;
+
+        # mlx-lm is a git dependency that needs setuptools
+        mlx-lm = prev.mlx-lm.overrideAttrs (old: {
+          nativeBuildInputs = (old.nativeBuildInputs or [ ]) ++ [
+            final.setuptools
+          ];
+        });
+      };
+
+      pythonSet = (pkgs.callPackage inputs.pyproject-nix.build.packages {
+        inherit python;
+      }).overrideScope (
+        lib.composeManyExtensions [
+          inputs.pyproject-build-systems.overlays.default
+          overlay
+          exoOverlay
+          buildSystemsOverlay
+        ]
+      );
+      exoVenv = pythonSet.mkVirtualEnv "exo-env" workspace.deps.default;
+
+      # Virtual environment with dev dependencies for testing
+      testVenv = pythonSet.mkVirtualEnv "exo-test-env" (
+        workspace.deps.default // {
+          exo = [ "dev" ]; # Include pytest, pytest-asyncio, pytest-env
+        }
+      );
+
+      exoPackage = pkgs.runCommand "exo"
+        {
+          nativeBuildInputs = [ pkgs.makeWrapper ];
+        }
+        ''
+          mkdir -p $out/bin
+
+          # Create wrapper scripts
+          for script in exo exo-master exo-worker; do
+            makeWrapper ${exoVenv}/bin/$script $out/bin/$script \
+              --set DASHBOARD_DIR ${self'.packages.dashboard}
+          done
+        '';
+    in
+    {
+      # Python package only available on macOS (requires MLX/Metal)
+      packages = lib.optionalAttrs pkgs.stdenv.hostPlatform.isDarwin {
+        exo = exoPackage;
+        # Test environment for running pytest outside of Nix sandbox (needs GPU access)
+        exo-test-env = testVenv;
+      };
+
+      checks = {
+        # Ruff linting (works on all platforms)
+        lint = pkgs.runCommand "ruff-lint" { } ''
+          export RUFF_CACHE_DIR="$TMPDIR/ruff-cache"
+          ${pkgs.ruff}/bin/ruff check ${inputs.self}/
+          touch $out
+        '';
+      };
+    };
+}