A minimal build backend for uv: uv_build (#11446)

uv itself is a large package with many dependencies and lots of
features. To build a package using the uv build backend, you shouldn't
have to download and install the entirety of uv. For platform where we
don't provide wheels, it should be possible and fast to compile the uv
build backend. To that end, we're introducing a python package that
contains a trimmed down version of uv that only contains the build
backend, with a minimal dependency tree in rust.

The `uv_build` package is publish from CI just like uv itself. It is
part of the workspace, but has much less dependencies for its own
binary. We're using cargo deny to enforce that the network stack is not
part of the dependencies. A new build profile ensure we're getting the
minimum possible binary size for a rust binary.

---------

Co-authored-by: Zanie Blue <contact@zanie.dev>

.github/workflows/build-binaries.yml

@@ -19,6 +19,8 @@ on:
       - pyproject.toml
       - Cargo.toml
       - .cargo/config.toml
+      - crates/uv-build/Cargo.toml
+      - crates/uv-build/pyproject.toml
       # Toolchain or dependency versions
       - Cargo.lock
       - rust-toolchain.toml
@@ -47,6 +49,8 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
+
+      # uv
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
       - name: "Build sdist"
@@ -65,9 +69,26 @@ jobs:
       - name: "Upload sdist"
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-sdist
+          name: wheels_uv-sdist
           path: dist
 
+      # uv-build
+      - name: "Build sdist uv-build"
+        uses: PyO3/maturin-action@v1
+        with:
+          command: sdist
+          args: --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+      - name: "Test sdist uv-build"
+        run: |
+          pip install crates/uv-build/dist/${{ env.PACKAGE_NAME }}_build-*.tar.gz --force-reinstall
+          ${{ env.MODULE_NAME }}-build --help
+          python -m ${{ env.MODULE_NAME }}_build --help
+      - name: "Upload sdist uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-sdist
+          path: crates/uv-build/dist
+
   macos-x86_64:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: macos-14
@@ -79,6 +100,8 @@ jobs:
           architecture: x64
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels - x86_64"
         uses: PyO3/maturin-action@v1
         with:
@@ -108,6 +131,18 @@ jobs:
             *.tar.gz
             *.sha256
 
+      # uv-build
+      - name: "Build wheels uv-build - x86_64"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: x86_64
+          args: --profile minimal-size --locked --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+      - name: "Upload wheels uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-macos-x86_64
+          path: crates/uv-build/dist
+
   macos-aarch64:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: macos-14
@@ -119,6 +154,8 @@ jobs:
           architecture: arm64
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels - aarch64"
         uses: PyO3/maturin-action@v1
         with:
@@ -154,6 +191,23 @@ jobs:
             *.tar.gz
             *.sha256
 
+      # uv-build
+      - name: "Build wheels uv-build - aarch64"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: aarch64
+          args: --profile minimal-size --locked --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+      - name: "Test wheel - aarch64"
+        run: |
+          pip install ${{ env.PACKAGE_NAME }}_build --no-index --find-links crates/uv-build/dist --force-reinstall
+          ${{ env.MODULE_NAME }}-build --help
+          python -m ${{ env.MODULE_NAME }}_build --help
+      - name: "Upload wheels uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-aarch64-apple-darwin
+          path: crates/uv-build/dist
+
   windows:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: github-windows-2022-x86_64-8
@@ -174,6 +228,8 @@ jobs:
           architecture: ${{ matrix.platform.arch }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels"
         uses: PyO3/maturin-action@v1
         with:
@@ -190,7 +246,7 @@ jobs:
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.platform.target }}
+          name: wheels_uv-${{ matrix.platform.target }}
           path: dist
       - name: "Archive binary"
         shell: bash
@@ -207,6 +263,25 @@ jobs:
             *.zip
             *.sha256
 
+      # uv-build
+      - name: "Build wheels uv-build"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: ${{ matrix.platform.target }}
+          args: --profile minimal-size --locked --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+      - name: "Test wheel uv-build"
+        if: ${{ !startsWith(matrix.platform.target, 'aarch64') }}
+        shell: bash
+        run: |
+          pip install ${{ env.PACKAGE_NAME }}_build --no-index --find-links crates/uv-build/dist --force-reinstall
+          ${{ env.MODULE_NAME }}-build --help
+          python -m ${{ env.MODULE_NAME }}_build --help
+      - name: "Upload wheels uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-${{ matrix.platform.target }}
+          path: crates/uv-build/dist
+
   linux:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: depot-ubuntu-latest-4
@@ -223,6 +298,8 @@ jobs:
           architecture: x64
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels"
         # Use patch for https://github.com/PyO3/maturin-action/issues/331
         uses: PyO3/maturin-action@711bb9fcefaea0b45a7d625ee2c265fd9fe7f3e5
@@ -255,13 +332,11 @@ jobs:
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.target }}
+          name: wheels_uv-${{ matrix.target }}
           path: dist
       - name: "Archive binary"
         shell: bash
         run: |
-          set -euo pipefail
-
           TARGET=${{ matrix.target }}
           ARCHIVE_NAME=uv-$TARGET
           ARCHIVE_FILE=$ARCHIVE_NAME.tar.gz
@@ -279,9 +354,29 @@ jobs:
             *.tar.gz
             *.sha256
 
+      # uv-build
+      - name: "Build wheels uv-build"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: ${{ matrix.target }}
+          manylinux: auto
+          args: --profile minimal-size --locked --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+      - name: "Test wheel uv-build"
+        if: ${{ startsWith(matrix.target, 'x86_64') }}
+        run: |
+          pip install ${{ env.PACKAGE_NAME }}_build --no-index --find-links crates/uv-build/dist --force-reinstall
+          ${{ env.MODULE_NAME }}-build --help
+          python -m ${{ env.MODULE_NAME }}_build --help
+      - name: "Upload wheels uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-${{ matrix.target }}
+          path: crates/uv-build/dist
+
   linux-arm:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: ubuntu-latest
+    timeout-minutes: 30
     strategy:
       matrix:
         platform:
@@ -302,6 +397,8 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels"
         uses: PyO3/maturin-action@v1
         with:
@@ -329,13 +426,11 @@ jobs:
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.platform.target }}
+          name: wheels_uv-${{ matrix.platform.target }}
           path: dist
       - name: "Archive binary"
         shell: bash
         run: |
-          set -euo pipefail
-
           TARGET=${{ matrix.platform.target }}
           ARCHIVE_NAME=uv-$TARGET
           ARCHIVE_FILE=$ARCHIVE_NAME.tar.gz
@@ -353,9 +448,40 @@ jobs:
             *.tar.gz
             *.sha256
 
+      # uv-build
+      - name: "Build wheels uv-build"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: ${{ matrix.platform.target }}
+          # On `aarch64`, use `manylinux: 2_28`; otherwise, use `manylinux: auto`.
+          manylinux: ${{ matrix.platform.arch == 'aarch64' && '2_28' || 'auto' }}
+          docker-options: ${{ matrix.platform.maturin_docker_options }}
+          args: --profile minimal-size --locked --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+      - uses: uraimo/run-on-arch-action@v2
+        name: "Test wheel uv-build"
+        with:
+          arch: ${{ matrix.platform.arch == 'arm' && 'armv6' || matrix.platform.arch }}
+          distro: ${{ matrix.platform.arch == 'arm' && 'bullseye' || 'ubuntu20.04' }}
+          githubToken: ${{ github.token }}
+          install: |
+            apt-get update
+            apt-get install -y --no-install-recommends python3 python3-pip python-is-python3
+            pip3 install -U pip
+          run: |
+            pip install ${{ env.PACKAGE_NAME }}_build --no-index --find-links crates/uv-build/dist --force-reinstall
+            ${{ env.MODULE_NAME }}-build --help
+            # TODO(konsti): Enable this test on all platforms, currently `find_uv_bin` is failing to discover uv here.
+            # python -m ${{ env.MODULE_NAME }}_build --help
+      - name: "Upload wheels uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-${{ matrix.platform.target }}
+          path: crates/uv-build/dist
+
   # Like `linux-arm`.
   linux-s390x:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
+    timeout-minutes: 30
     runs-on: depot-ubuntu-latest-4
     strategy:
       matrix:
@@ -370,6 +496,8 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels"
         uses: PyO3/maturin-action@v1
         with:
@@ -397,13 +525,11 @@ jobs:
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.platform.target }}
+          name: wheels_uv-${{ matrix.platform.target }}
           path: dist
       - name: "Archive binary"
         shell: bash
         run: |
-          set -euo pipefail
-
           TARGET=${{ matrix.platform.target }}
           ARCHIVE_NAME=uv-$TARGET
           ARCHIVE_FILE=$ARCHIVE_NAME.tar.gz
@@ -421,6 +547,36 @@ jobs:
             *.tar.gz
             *.sha256
 
+      # uv-build
+      - name: "Build wheels uv-build"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: ${{ matrix.platform.target }}
+          manylinux: auto
+          docker-options: ${{ matrix.platform.maturin_docker_options }}
+          args: --profile minimal-size --locked --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+      - uses: uraimo/run-on-arch-action@v2
+        if: matrix.platform.arch != 'ppc64'
+        name: "Test wheel uv-build"
+        with:
+          arch: ${{ matrix.platform.arch }}
+          distro: ubuntu20.04
+          githubToken: ${{ github.token }}
+          install: |
+            apt-get update
+            apt-get install -y --no-install-recommends python3 python3-pip python-is-python3
+            pip3 install -U pip
+          run: |
+            pip install ${{ env.PACKAGE_NAME }}-build --no-index --find-links crates/uv-build/dist --force-reinstall
+            ${{ env.MODULE_NAME }}-build --help
+            # TODO(konsti): Enable this test on all platforms, currently `find_uv_bin` is failing to discover uv here.
+            # python -m ${{ env.MODULE_NAME }}-build --help
+      - name: "Upload wheels uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-${{ matrix.platform.target }}
+          path: crates/uv-build/dist
+
   # Like `linux-arm`, but install the `gcc-powerpc64-linux-gnu` package.
   linux-powerpc:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
@@ -444,6 +600,8 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels"
         uses: PyO3/maturin-action@v1
         with:
@@ -479,13 +637,11 @@ jobs:
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.platform.target }}
+          name: wheels_uv-${{ matrix.platform.target }}
           path: dist
       - name: "Archive binary"
         shell: bash
         run: |
-          set -euo pipefail
-
           TARGET=${{ matrix.platform.target }}
           ARCHIVE_NAME=uv-$TARGET
           ARCHIVE_FILE=$ARCHIVE_NAME.tar.gz
@@ -503,6 +659,28 @@ jobs:
             *.tar.gz
             *.sha256
 
+      # uv-build
+      - name: "Build wheels uv-build"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: ${{ matrix.platform.target }}
+          manylinux: auto
+          docker-options: ${{ matrix.platform.maturin_docker_options }}
+          args: --profile minimal-size --locked --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+          before-script-linux: |
+            if command -v yum &> /dev/null; then
+                yum update -y
+                yum -y install epel-release
+                yum repolist
+                yum install -y gcc-powerpc64-linux-gnu
+            fi
+      # TODO(charlie): Re-enable testing for PPC wheels.
+      - name: "Upload wheels uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-${{ matrix.platform.target }}
+          path: crates/uv-build/dist
+
   musllinux:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: ubuntu-latest
@@ -519,6 +697,8 @@ jobs:
           architecture: x64
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels"
         uses: PyO3/maturin-action@v1
         with:
@@ -537,17 +717,17 @@ jobs:
             .venv/bin/pip install --upgrade pip
             .venv/bin/pip install ${{ env.PACKAGE_NAME }} --no-index --find-links dist/ --force-reinstall
             .venv/bin/${{ env.MODULE_NAME }} --help
+            # TODO(konsti): Enable this test on all platforms, currently `find_uv_bin` is failing to discover uv here.
+            # .venv/bin/python -m ${{ env.MODULE_NAME }} --help
             .venv/bin/uvx --help
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.target }}
+          name: wheels_uv-${{ matrix.target }}
           path: dist
       - name: "Archive binary"
         shell: bash
         run: |
-          set -euo pipefail
-
           TARGET=${{ matrix.target }}
           ARCHIVE_NAME=uv-$TARGET
           ARCHIVE_FILE=$ARCHIVE_NAME.tar.gz
@@ -565,6 +745,32 @@ jobs:
             *.tar.gz
             *.sha256
 
+      # uv-build
+      - name: "Build wheels uv-build"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: ${{ matrix.target }}
+          manylinux: musllinux_1_1
+          args: --profile minimal-size --locked --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+      - name: "Test wheel uv-build"
+        if: matrix.target == 'x86_64-unknown-linux-musl'
+        uses: addnab/docker-run-action@v3
+        with:
+          image: alpine:3.12
+          options: -v ${{ github.workspace }}:/io -w /io
+          run: |
+            apk add python3
+            python3 -m venv .venv
+            .venv/bin/pip install --upgrade pip
+            .venv/bin/pip install ${{ env.PACKAGE_NAME }}-build --no-index --find-links crates/uv-build/dist --force-reinstall
+            .venv/bin/${{ env.MODULE_NAME }}-build --help
+            .venv/bin/python -m ${{ env.MODULE_NAME }}_build --help
+      - name: "Upload wheels uv-build"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-${{ matrix.target }}
+          path: crates/uv-build/dist
+
   musllinux-cross:
     if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-build') }}
     runs-on: ubuntu-latest
@@ -585,6 +791,8 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
       - name: "Prep README.md"
         run: python scripts/transform_readme.py --target pypi
+
+      # uv
       - name: "Build wheels"
         uses: PyO3/maturin-action@v1
         with:
@@ -605,6 +813,8 @@ jobs:
             python -m venv .venv
             .venv/bin/pip install ${{ env.PACKAGE_NAME }} --no-index --find-links dist/ --force-reinstall
             .venv/bin/${{ env.MODULE_NAME }} --help
+            # TODO(konsti): Enable this test on all platforms, currently `find_uv_bin` is failing to discover uv here.
+            # .venv/bin/python -m ${{ env.MODULE_NAME }} --help
             .venv/bin/uvx --help
       - uses: uraimo/run-on-arch-action@v2
         name: "Test wheel (manylinux)"
@@ -626,13 +836,11 @@ jobs:
       - name: "Upload wheels"
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.platform.target }}
+          name: wheels_uv-${{ matrix.platform.target }}
           path: dist
       - name: "Archive binary"
         shell: bash
         run: |
-          set -euo pipefail
-
           TARGET=${{ matrix.platform.target }}
           ARCHIVE_NAME=uv-$TARGET
           ARCHIVE_FILE=$ARCHIVE_NAME.tar.gz
@@ -650,3 +858,48 @@ jobs:
           path: |
             *.tar.gz
             *.sha256
+
+      # uv-build
+      - name: "Build wheels"
+        uses: PyO3/maturin-action@v1
+        with:
+          target: ${{ matrix.platform.target }}
+          manylinux: musllinux_1_1
+          args: --profile minimal-size --locked ${{ matrix.platform.arch == 'aarch64' && '--compatibility 2_17' || ''}} --out crates/uv-build/dist -m crates/uv-build/Cargo.toml
+          docker-options: ${{ matrix.platform.maturin_docker_options }}
+          rust-toolchain: ${{ matrix.platform.toolchain || null }}
+      - uses: uraimo/run-on-arch-action@v2
+        name: "Test wheel"
+        with:
+          arch: ${{ matrix.platform.arch }}
+          distro: alpine_latest
+          githubToken: ${{ github.token }}
+          install: |
+            apk add python3
+          run: |
+            python -m venv .venv
+            .venv/bin/pip install ${{ env.PACKAGE_NAME }}-build --no-index --find-links crates/uv-build/dist --force-reinstall
+            .venv/bin/${{ env.MODULE_NAME }}-build --help
+            # TODO(konsti): Enable this test on all platforms, currently `find_uv_bin` is failing to discover uv here.
+            # .venv/bin/python -m ${{ env.MODULE_NAME }}_build --help
+      - uses: uraimo/run-on-arch-action@v2
+        name: "Test wheel (manylinux)"
+        if: matrix.platform.arch == 'aarch64'
+        with:
+          arch: aarch64
+          distro: ubuntu20.04
+          githubToken: ${{ github.token }}
+          install: |
+            apt-get update
+            apt-get install -y --no-install-recommends python3 python3-pip python-is-python3
+            pip3 install -U pip
+          run: |
+            pip install ${{ env.PACKAGE_NAME }}-build --no-index --find-links crates/uv-build/dist --force-reinstall
+            ${{ env.MODULE_NAME }}-build --help
+            # TODO(konsti): Enable this test on all platforms, currently `find_uv_bin` is failing to discover uv here.
+            # python -m ${{ env.MODULE_NAME }}_build --help
+      - name: "Upload wheels"
+        uses: actions/upload-artifact@v4
+        with:
+          name: wheels_uv_build-${{ matrix.platform.target }}
+          path: crates/uv-build/dist

.github/workflows/ci.yml

@@ -107,6 +107,11 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           save-if: ${{ github.ref == 'refs/heads/main' }}
+      - name: "Check uv_build dependencies"
+        uses: EmbarkStudios/cargo-deny-action@v1
+        with:
+          command: check bans
+          manifest-path: crates/uv-build/Cargo.toml
       - name: "Install Rust toolchain"
         run: rustup component add clippy
       - name: "Clippy"

.github/workflows/publish-pypi.yml

@@ -12,8 +12,8 @@ on:
         type: string
 
 jobs:
-  pypi-publish:
-    name: Upload to PyPI
+  pypi-publish-uv:
+    name: Upload uv to PyPI
     runs-on: ubuntu-latest
     environment:
       name: release
@@ -25,8 +25,27 @@ jobs:
         uses: astral-sh/setup-uv@v5
       - uses: actions/download-artifact@v4
         with:
-          pattern: wheels-*
-          path: wheels
+          pattern: wheels_uv-*
+          path: wheels_uv
           merge-multiple: true
       - name: Publish to PyPi
-        run: uv publish -v wheels/*
+        run: uv publish -v wheels_uv/*
+
+  pypi-publish-uv-build:
+    name: Upload uv-build to PyPI
+    runs-on: ubuntu-latest
+    environment:
+      name: release
+    permissions:
+      # For PyPI's trusted publishing.
+      id-token: write
+    steps:
+      - name: "Install uv"
+        uses: astral-sh/setup-uv@v5
+      - uses: actions/download-artifact@v4
+        with:
+          pattern: wheels_uv_build-*
+          path: wheels_uv_build
+          merge-multiple: true
+      - name: Publish to PyPi
+        run: uv publish -v wheels_uv_build/*