feat(e2e): Source-built Python interpreter with uv deps by arrdem · Pull Request #830 · aspect-build/rules_py

arrdem · 2026-03-06T22:22:06Z

Summary

Stacked on #831 (no-binary-package support)

Builds CPython 3.11.9 from source with --with-pydebug (producing cp311d ABI tag)
Uses [tool.uv] no-binary-package = ["markupsafe"] to force sdist build
Tests verify the debug interpreter works and that markupsafe was built from sdist with the debug interpreter (cp311d in WHEEL metadata and .so filenames)

Key design

Custom Bazel rules (build_cpython, python_interpreter_wrapper, source_built_test) in defs.bzl
Transition rule activates the source-built toolchain via a build setting flag
The cp311d ABI tag in the built wheel is impossible to produce from pre-built wheels or PBS interpreters, definitively proving the custom interpreter was used

Test plan

Main tests pass (bazel test //...)
cd e2e && bazel test //cases/source-built-python/... passes (requires feat(uv): Support [tool.uv] no-binary-package #831)

🤖 Generated with Claude Code

CLAassistant · 2026-03-06T22:22:15Z

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
0 out of 2 committers have signed the CLA.

❌ aspect-marvin
❌ claude
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

aspect-workflows · 2026-03-06T22:23:22Z

Bazel 8 (Test)

All tests were cache hits

44 tests (100.0%) were fully cached saving 43s.

Bazel 9 (Test)

All tests were cache hits

44 tests (100.0%) were fully cached saving 1m 12s.

Bazel 8 (Test)

e2e

⚠️ Buildkite build #2742 failed.

@@aspect_rules_py++uv+sdist_build__source_built_python_test__markupsafe__3_0_3//:whl failed to build

python3 failed: error executing PySdistBuild command (from target @@aspect_rules_py++uv+sdist_build__source_built_python_test__markupsafe__3_0_3//:whl) bazel-out/k8-fastbuild-ST-fea2897b2333/bin/external/aspect_rules_py++uv+sdist_build__source_built_python_test__markupsafe__3_0_3/.build_venv/bin/python3 ... (remaining 3 arguments skipped)
 
Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
 
Error:   × Unable to initialize runfiles and unable to identify action layout
  │ interpreter

💡 To reproduce the build failures, run

bazel build @@aspect_rules_py++uv+sdist_build__source_built_python_test__markupsafe__3_0_3//:whl

Bazel 9 (Test)

e2e

⚠️ Buildkite build #2742 failed.

@@aspect_rules_py++uv+sdist_build__source_built_python_test__markupsafe__3_0_3//:whl failed to build

python3 failed: error executing PySdistBuild command (from sdist_build rule target @@aspect_rules_py++uv+sdist_build__source_built_python_test__markupsafe__3_0_3//:whl) bazel-out/k8-fastbuild-ST-fea2897b2333/bin/external/aspect_rules_py++uv+sdist_build__source_built_python_test__markupsafe__3_0_3/.build_venv/bin/python3 ... (remaining 3 arguments skipped)
 
Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
 
Error:   × Unable to initialize runfiles and unable to identify action layout
  │ interpreter

💡 To reproduce the build failures, run

bazel build @@aspect_rules_py++uv+sdist_build__source_built_python_test__markupsafe__3_0_3//:whl

Bazel 8 (Test)

examples/uv_pip_compile

⚠️ Buildkite build #2742 failed.

Read the `no-binary-package` list from pyproject.toml's `[tool.uv]` section. For listed packages: - Force sdist build even when a -none-any wheel exists - Exclude all pre-built wheels from the install configuration - Fail if no sdist is available in the lockfile This mirrors uv's own `no-binary-package` behavior, enabling use cases like building C extensions with custom interpreters (e.g. debug builds). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Demonstrates building CPython 3.11.9 from source as a Bazel build action, registering it as a py_runtime toolchain gated behind a build setting, and using it with uv-sourced C extension dependencies (markupsafe). Key components: - Custom `build_cpython` Starlark rule that runs ./configure && make && make install as a build action producing a tree artifact - Wrapper script that sets PYTHONHOME to bridge the tree artifact layout with py_runtime's interpreter expectations - `source_built_test` transition rule that activates the custom toolchain via a string_flag/config_setting gate - MODULE.bazel `include()` to keep case-specific configuration self-contained - Two tests: basic interpreter verification and uv deps with markupsafe (C extension) proving wheel compatibility Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

## Summary - Reads `[tool.uv] no-binary-package` from `pyproject.toml` to identify packages that must be built from source - For listed packages: forces sdist build (even for -none-any wheels), excludes all pre-built wheels from the install config - Adds a safety `fail()` if a no-binary package has no sdist in the lockfile This mirrors uv's own `no-binary-package` behavior, enabling use cases like building C extensions with custom/debug interpreters. ## Test plan - [x] All 44 main tests pass (`bazel test //...`) - [x] All 16 e2e tests pass (`cd e2e && bazel test //...`) - [ ] Stacked PR #830 exercises this with source-built debug Python + markupsafe sdist 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: claude <claude@anthropic.com> Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Use --without-ensurepip instead of --with-ensurepip=install when building CPython from source. The ensurepip step installs pip and setuptools into the interpreter tree, which is unnecessary for our use case and was contributing to sdist build failures in CI. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

arrdem · 2026-03-07T00:58:44Z

Replaced by #833

claude and others added 2 commits March 6, 2026 15:58

arrdem force-pushed the arrdem/e2e-source-built-python branch from a69ae14 to cf4a080 Compare March 6, 2026 23:04

Pre-commit changes

897849a

arrdem mentioned this pull request Mar 6, 2026

feat(uv): Support [tool.uv] no-binary-package #831

Merged

3 tasks

arrdem changed the base branch from main to arrdem/uv-no-binary-package March 6, 2026 23:11

Base automatically changed from arrdem/uv-no-binary-package to main March 6, 2026 23:14

arrdem closed this Mar 7, 2026

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

feat(e2e): Source-built Python interpreter with uv deps#830

feat(e2e): Source-built Python interpreter with uv deps#830
arrdem wants to merge 4 commits intomainfrom
arrdem/e2e-source-built-python

arrdem commented Mar 6, 2026 •

edited

Loading

Uh oh!

CLAassistant commented Mar 6, 2026 •

edited

Loading

Uh oh!

aspect-workflows Bot commented Mar 6, 2026 •

edited

Loading

Uh oh!

arrdem commented Mar 7, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

Uh oh!

Conversation

arrdem commented Mar 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Key design

Test plan

Uh oh!

CLAassistant commented Mar 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

aspect-workflows Bot commented Mar 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Bazel 8 (Test)

Bazel 9 (Test)

Bazel 8 (Test)

e2e

Bazel 9 (Test)

e2e

Bazel 8 (Test)

examples/uv_pip_compile

Uh oh!

arrdem commented Mar 7, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

arrdem commented Mar 6, 2026 •

edited

Loading

CLAassistant commented Mar 6, 2026 •

edited

Loading

aspect-workflows Bot commented Mar 6, 2026 •

edited

Loading