[edolstra]

Motivation

The flake regression jobs vary between ~1 and ~12 minutes (e.g. https://github.com/DeterminateSystems/nix-src/actions/runs/40242643720), so we have many short jobs that mostly spend their time on setup, or worse, waiting for an available runner.

Implementation

Regroup the globs into 6 ranges that each take roughly 10 minutes, based on test step durations from the last 5 merge queue runs. This reduces the number of jobs from 42 to 18.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Updated the regression test grouping in the build workflow from fourteen groups to six. The existing Nix configuration test entries are unchanged.

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No actionable comments were generated in the recent review.

Recent review info

Run configuration

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• Layers: defaults
• Review profile: CHILL
• Plan: Essentials
• Run ID: 27fea9a7-ce52-4b90-acd8-303474f2e1ce

Commits

Reviewing files that changed from the base of the PR and between 240bbbc and 21e3d7e.

Files selected for processing: 1

• .github/workflows/build.yml

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Walkthrough

The flake_regressions workflow matrix now uses six broader glob groups instead of fourteen. The comment states that each group takes roughly 10 minutes. The existing nix_config matrix entries remain unchanged.

Changes: Regression test matrix

Layer / File(s)	Summary
Regression-test matrix groups .github/workflows/build.yml	The matrix now uses six broader glob groups instead of fourteen. The comment states that each group takes roughly 10 minutes.

Priority: Low

Estimated code review effort: 2 (Simple) | ~5 minutes

Change: Other

Possibly related PRs

• DeterminateSystems/nix-src#728: It aggregates statistics artifacts from flake_regressions matrix jobs, so its aggregation must account for the revised matrix.

Suggested reviewers: cole-h

Merge Risk: Minimal · up to 21e3d

The workflow matrix change is mergeable with no identified correctness or availability risk.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: combining flake regression globs into fewer, longer jobs.
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)

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