sortcpp

Bazel, C++ and pybind11 sample with c++ tests, python tests and python wheel packaging.

Inspired by Mizux/bazel-pybind11

Features

• bazel modules
• bazelisk
• gazelle with python and cpp plugin
• pyproject + poetry + rules_python + rules_pycross
• buildifier
• usage of numpy dependancy
• supports remote build/execution

IDE

VS Code

• starlark autocompletion link
• c++ autocompletion link
• python autocompletion link

Prerequisites

• Bazelisk

How to use:

Test

Test all targets

bazel test //...

Test individual targets

bazel test //sortcpp/src:sortcpp_test
bazel test //sortcpp:sortcpp_test

To see stdout check the log files or use bazel run

bazel run //sortcpp/src:sortcpp_test
bazel run //sortcpp:sortcpp_test

Build

To build all targets in the workspace

bazel build //...

Build python wheel

bazel build //sortcpp:wheel
tar tvf $(bazel cquery //sortcpp:wheel --output files 2>/dev/null)

Install python wheel

bazel build //sortcpp:wheel
tar tvf $(bazel cquery //sortcpp:wheel --output files 2>/dev/null)
pip install $(bazel cquery //src/python:wheel --output files 2>/dev/null) --force-reinstall

How to use the installed python package

from sortcpp import sort_array
sort_array([9, 5, 3])
sort_array([9, -1, 10, 0, 3])

Gazelle - Automated BUILD file generation

Gazelle automatically generates and updates BUILD.bazel files for your project. This workspace is configured with multi-language Gazelle support.

Using Gazelle

Gazelle is configured to support Python and C++ (other languages can also be configured).

# Generate/update BUILD files for all languages (C++, Python, Go)
bazel run //:gazelle

# Check what Gazelle would change without applying (dry-run)
bazel run //:gazelle.check

For C++ projects, Gazelle will:

• Detect header and source files
• Generate appropriate cc_library, cc_binary, and cc_test targets
• Resolve dependencies between targets
• Support Conan dependencies when configured (TODO)

For Python projects, Gazelle will:

• Generate py_library, py_binary, and py_test targets
• Detect imports and create appropriate dependencies
• Handle package structure and module dependencies
• Integrate with Poetry/pip dependencies

The configuration is defined in BUILD.bazel:11-16.

Adding new external Python dependencies

When adding new external Python dependencies, follow these steps:

1. Add dependency to pyproject.toml:

   [tool.poetry.dependencies]
   new-package = "^1.0.0"

2. Update Poetry lock file:

   poetry lock

3. Generate new Bazel lock file:

   bazel run //:update_poetry_lock_file

4. Update Gazelle mappings and BUILD files:

   bazel run //:gazelle

This workflow uses rules_pycross for cross-platform Python dependency management and Poetry for dependency resolution.

Build in Docker

# Start interactive Docker container with Bazel
docker run --rm -it \
  --platform linux/amd64 \
  --entrypoint /bin/bash \
  -v "$(pwd)":/src/workspace \
  -v /tmp/build_output:/tmp/build_output \
  -w /src/workspace \
  gcr.io/bazel-public/bazel:8.4.1

Inside the container, you can use regular Bazel commands:

# Build all targets
bazel build //...

# Run tests
bazel test //...

# Build Python wheel
bazel build //sortcpp:wheel

# Use remote execution (if configured)
bazel build //... --config=cache --config=remote_amd

This provides a consistent Linux AMD64 environment for builds and testing.

Remote Build and Execution

This project supports remote build and execution for faster builds through caching and distributed execution.

Setup

Remote execution can be configured with services like BuildBuddy. Setup typically takes about 10 minutes to configure.

Once configured, you can use flags like:

# Build with remote cache and execution
bazel build //... --config=cache --config=remote

# Test with remote execution
bazel test //... --config=cache --config=remote

Benefits

• Faster builds: Distributed execution across multiple machines
• Build caching: Shared cache across team and CI/CD
• Cross-platform builds: Build for different architectures without local toolchains
• Build insights: Web UI for build analysis and debugging

For setup instructions, see the BuildBuddy Quickstart Guide.

Other examples on how to build python wheels

• Pybind11 + cmake + bazel + gtest https://github.com/Mizux/bazel-pybind11/tree/main

• bazel https://github.com/tensorflow/tensorflow

• Pybind11 + cmake + Scikit Build (invokes cmake under the hood) https://github.com/scikit-build/scikit-build-sample-projects/tree/main/projects/hello-pybind11

• pybind + cmake + pypa/cibuildwheel (build python wheels for multiple target platforms) https://github.com/pybind/cmake_example

• cpp con with presentation on python bindings https://www.youtube.com/watch?v=rB7c69Z5Kus

• nanobind https://nanobind.readthedocs.io/en/latest/