ci: shard tracer-release system tests four ways

[bm1549]

Description

Link (AppGate required)

Each of the 25 tracer-release system-test definitions currently runs its scenario list serially. This adds native parallel: 4, producing 100 execution lanes. A checked-in selector sorts and deduplicates the canonical scenario set, then assigns disjoint round-robin slices using GitLab's 1-based node index.

One system-tests SHA is resolved in prepare code, published as a dotenv artifact, and checked out exactly by every shard. Required Python and PHP tests cover selector behavior, exact-once coverage, the shared pin, and all 25 generated job definitions. Valgrind is unchanged.

Current producer output splits 96 scenario executions into [24, 24, 24, 24]. Scenario-phase wall clock can approach one quarter of the current time; setup and weblog build work are repeated, and the slowest shard still sets wall clock.

Draft integration note: merge this after #4144 and #4142, then rebase. During conflict resolution, keep the fixed source/image pair from #4144, retain the shard selector, add producer-level PARAMETRIC exclusion, and remove the redundant unsharded extractor path.

Tested with:

• Selector suite: 4 passed, including exact-once and real staggered-input coverage
• Generated-pipeline pin/wiring contract under PHP 8.2
• Generated package YAML: 25 definitions × 4 shards; all pin and selector contracts present
• Exact shallow checkout, origin-advance simulation, PHP lint, and git diff --check

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[datadog-official]

 

⚠️ Warnings

❌ Your PR has failed checks. Please review the issues below and take necessary action before merging.

🚦 3 Pipeline jobs failed

DataDog/apm-reliability/dd-trace-php | bundle for reliability env

View more details · View in GitLab

DataDog/apm-reliability/dd-trace-php | merge-gate

View more details · View in GitLab

DataDog/apm-reliability/dd-trace-php | publish docker image for system tests

View more details · View in GitLab

ℹ️ Info

No other issues found (see more)

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 60.62% (-0.01%)

Useful? React with 👍 / 👎

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 566f5df | Docs | View more details | Give us feedback!}