Port v1 recipe support to py-rattler-build by jsmolic · Pull Request #5924 · conda/conda-build

jsmolic · 2026-02-17T15:02:18Z

Closes: #5891
Closes: #5892
Closes: #5893

Description

This PR continues the work started in #5880 replacing the rattler-build CLI subprocess calls with the new py-rattler API.

It currently supports rendering and building v1 packages. Support for conda-debug was removed due to issues with the debug API; which has since been refactored in py-rattler and will be integrated in a subsequent PR to reduce the complexity in this one.

Py-rattler API documentation is available here, but this summary describes how the API is used within this PR for easier review:

The logic for finding rattler-build binary has been removed as we are no longer using the CLI tool.
Core functionality of the code is in run_rattler() and process_recipe() functions.
run_rattler() initializes configuration variables based on the values stored in argparse.Namespace and Config objects. It delegates recipe processing to a separate function and handles the build summary reporting at the end.
Configuration file discovery logic has remained largely unchanged from the previous version
Most of the rattler-build general settings are now handled through ToolConfiguration, while PlatformConfig and RenderConfig define platform-specific settings and rendering behavior, respectively.
Configuration files are loaded using VariantConfig.from_file() method, respecting the order in which they are stacked.

process_recipes() performs loading, rendering, build and testing the recipe. Recipes are loaded with Stage0Recipe.from_file(), rendered with recipe.render() and build with variant.run_build(). If enabled, testing runs after the build to follow v0 recipe behavior in conda-build.

Progress reporting

Py-rattler uses the ProgressCallback protocol for progress reporting, with some built-in implementations and options to define custom callbacks. This PR integrates SimpleProgressCallback and forwards the event levels and messages to conda’s logging system. This implementation is minimal but additional UI improvements are expected to be added in future versions.

Build results and summary

Build results are stored in dataclasses that contain recipe and output info about build status and error messages. Each process_recipe() call returns a RecipeResult object containing all relevant build summary details. Short summary is displayed upon completion, displaying per-recipe and per-output build results along with any errors if present.

Limitations/features currently not implemented:

As previously mentioned, noconda-debug support, will be added in a separate PR
No multi-output with staging outputs recipe support. It is currently labeled as an experimental feature in rattler-build and depends on the draft CEP: CEP XXXX: define the staging output for split builds in the v1 recipe format ceps#102
No multichannel support, depends on Multichannel support rattler#1327
Package upload and networking-specific configuration are currently not supported, subsequent work is planned in Support anaconda.org upload after build for v1 recipes #5894 and Add network configuration for v1 recipe support #5898
User documentation will be added in a separate PR (Create documentation for v1 recipes #5896)

Checklist - did you ...

Add a file to the news directory (using the template) for the next release's release notes?
Add / update necessary tests?
Add / update outdated documentation?

conda_build/_rattler_build/compat.py

codspeed-hq · 2026-03-04T03:07:23Z

Merging this PR will not alter performance

✅ 5 untouched benchmarks

_{Comparing jsmolic:v1-integration-py-rattler (5655d49) with main (805bc5f)¹}

No successful run was found on main (26ac205) during the generation of this report, so 805bc5f was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

jaimergp

Some comments about docstrings and default values, and I'm also curious about failure modes.

conda_build/_rattler_build/compat.py

tests/cli/test_main_build.py

conda_build/_rattler_build/compat.py

issues rattler-build debug support has been dropped in prefix-dev/rattler-build@c607abf due to the awkward implementation. It is going to be implemented properly with the new API so we can readd debug support once the code will make it into rattler-build source.

It has been suggested that moving these definitions out of process_recipes function makes more sense. The drawback is that we won't be able to support the experimental staging outputs because we need to be inspect outputs after loading the recipe file. This should be documented as a limitation of the current implementation. Once the staging outputs are properly supported in rattler-build we can come back and implement this in conda-build.

We are going to initially simply fork py-rattler-build's progress callback and pass the level and messages to conda's logging

We can't use it in py-rattler-build to increase verbosity

py-rattler-build does not auto discover recipe variants so we don't need to anything about this

Use py-rattler-build's Package API to run the tests. Use the test output to report it back when tests fail in the build summary.

- This adds the initial v1 recipes test file

This commit adds dataclasses for easier storing and reporting recipe and output build results. We can use them to store info during the build process such as recipe/output name, success status and error message if any; and use it to re-raise CondaBuildUserError in the end and report a meaningful build summary.

conda-bot added this to 🔎 Review Feb 17, 2026

github-project-automation bot moved this to 🆕 New in 🔎 Review Feb 17, 2026

conda-bot added the cla-signed [bot] added once the contributor has signed the CLA label Feb 17, 2026