This directory contains the Buildkite pipeline definitions for Ray CI, plus the rules that decide which tests run on a given change.

Pipelines are defined in the *.rayci.yml files in this directory and are generated and run by rayci, Ray's CI orchestration tool. Each file groups the steps for one area (for example, core.rayci.yml, data.rayci.yml, doc.rayci.yml).

Which steps run on a given pull request is determined by mapping changed file paths to tags. Two rule files drive this:

• test.rules.txt is the conditional rule set. Rules are evaluated in order and the first match wins. A rule with no @ tags is a skip rule (it matches but emits nothing), and a trailing * catch-all fans unmatched changes out to the full suite.
• always.rules.txt is an always-on overlay applied to every change.

rayci parses these files (its test-rules command) and runs the steps whose tags are emitted. See the header comment in each rules file for the full format.

ci/pipeline/determine_tests_to_run.py is an in-repo reference implementation of the same rule-file format. It is not the live evaluator; rayci is.