fix(static-quality-gates): really skip per-PR size thresholds on main

[rdesgroppes]

What does this PR do?

Derive is_on_main_branch from the branch name, the way tasks/package.py already does, instead of comparing the ancestor to HEAD: get_ancestor replaces the ancestor with the parent commit on main, so that comparison was always False and main pipelines were evaluated as pull requests.

The flag now also skips the PR lookup, and get_ancestor no longer computes a flag it throws away.

Motivation

https://gitlab.ddbuild.io/DataDog/datadog-agent/-/jobs/1993405414 failed on main for a test-only fix, 7 of 33 gates reporting growth nobody introduced:

Gate static_quality_gate_agent_deb_amd64 failed ❌ with the following message:
On-wire size increase of 90.02 MiB exceeds the per-PR wire threshold of 5.0 MiB
Gate static_quality_gate_agent_msi failed ❌ with the following message:
On-wire size increase of 75.83 MiB exceeds the per-PR wire threshold of 5.0 MiB
Gate static_quality_gate_agent_rpm_arm64 failed ❌ with the following message:
On-wire size increase of 81.56 MiB exceeds the per-PR wire threshold of 5.0 MiB
Gate static_quality_gate_agent_suse_arm64 failed ❌ with the following message:
On-wire size increase of 81.56 MiB exceeds the per-PR wire threshold of 5.0 MiB
Gate static_quality_gate_agent_suse_arm64_fips failed ❌ with the following message:
On-wire size increase of 76.9 MiB exceeds the per-PR wire threshold of 5.0 MiB
Gate static_quality_gate_docker_cluster_agent_amd64 failed ❌ with the following message:
On-wire size increase of 36.81 MiB exceeds the per-PR wire threshold of 5.0 MiB
Gate static_quality_gate_docker_dogstatsd_amd64 failed ❌ with the following message:
On-wire size increase of 7.65 MiB exceeds the per-PR wire threshold of 5.0 MiB

The baseline was garbage (#55595 is meant to fix it): the parent commit was built by 2 concurrent push pipelines (https://gitlab.ddbuild.io/DataDog/datadog-agent/-/pipelines/133869316 / https://gitlab.ddbuild.io/DataDog/datadog-agent/-/pipelines/133869408), and reading their duplicate gauges mid-submission made the averaging ancestor query return exactly half the real size.

Deltas measured against a parent commit are not a pipeline's own work, so the per-PR check has no business running on main.

The same PR lookup also made the job comment on #55434, an unrelated pull request whose head branch happens to be main:

Updated comment on PR #55434 - fix(data-race): lock ntmConfig.GetNode for concurrent access (#55389)

Describe how you validated your changes

dda inv invoke-unit-tests.run --directory=tasks/unit_tests/static_quality_gates runs 194 tests green, and the added test_per_pr_threshold_skipped_on_main is the only failure once is_on_main_branch is forced back to False.

Additional Notes

Release-branch pipelines still evaluate the per-PR thresholds, since get_default_branch() returns main there, but they cannot fail on it because the Exit is intentionally skipped for release branches.

[github-actions]

AI review by Codex (OpenAI) - workflow run

patch is correct — branch-name detection now correctly skips per-PR thresholds and branch PR lookup on main, with focused integration coverage.

[dd-octo-sts]

Files inventory check summary

File checks results against ancestor ad97d80a:

Results for datadog-agent_7.84.0~devel.git.569.0dd02cd.pipeline.133904752-1_amd64.deb:

No change detected

Results for datadog-iot-agent_7.84.0~devel.git.569.0dd02cd.pipeline.133904752-1_amd64.deb:

No change detected

[dd-octo-sts]

Static quality checks

✅ Please find below the results from static quality gates
Comparison made with ancestor ad97d80
📊 Static Quality Gates Dashboard
🔗 SQG Job

32 successful checks with minimal change (< 2 KiB)

	Quality gate	Current Size
✅	agent_deb_amd64	761.393 MiB
✅	agent_deb_amd64_fips	713.920 MiB
✅	agent_heroku_amd64	312.966 MiB
✅	agent_rpm_amd64	761.376 MiB
✅	agent_rpm_amd64_fips	713.904 MiB
✅	agent_rpm_arm64	737.301 MiB
✅	agent_rpm_arm64_fips	693.135 MiB
✅	agent_suse_amd64	761.376 MiB
✅	agent_suse_amd64_fips	713.904 MiB
✅	agent_suse_arm64	737.301 MiB
✅	agent_suse_arm64_fips	693.135 MiB
✅	docker_agent_amd64	820.409 MiB
✅	docker_agent_arm64	821.369 MiB
✅	docker_agent_jmx_amd64	1011.321 MiB
✅	docker_agent_jmx_arm64	1001.062 MiB
✅	docker_cluster_agent_amd64	211.254 MiB
✅	docker_cluster_agent_arm64	224.398 MiB
✅	docker_cws_instrumentation_amd64	7.439 MiB
✅	docker_cws_instrumentation_arm64	6.877 MiB
✅	docker_dogstatsd_amd64	39.545 MiB
✅	docker_dogstatsd_arm64	37.623 MiB
✅	docker_host_profiler_amd64	306.862 MiB
✅	docker_host_profiler_arm64	318.167 MiB
✅	dogstatsd_deb_amd64	30.290 MiB
✅	dogstatsd_deb_arm64	28.302 MiB
✅	dogstatsd_rpm_amd64	30.290 MiB
✅	dogstatsd_suse_amd64	30.290 MiB
✅	iot_agent_deb_amd64	46.564 MiB
✅	iot_agent_deb_arm64	43.200 MiB
✅	iot_agent_deb_armhf	44.011 MiB
✅	iot_agent_rpm_amd64	46.564 MiB
✅	iot_agent_suse_amd64	46.563 MiB

[cit-pr-commenter-54b7da]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Job ID: 84f9137f-b568-4f68-b9eb-95eff108d54d

Baseline: ad97d80
Comparison: 0dd02cd
Diff

Optimization Goals: ✅ No significant changes detected

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	quality_gate_security_no_fs_load	memory utilization	+0.25	[+0.17, +0.34]	1	Logs bounds checks dashboard
➖	dsd_uds_10mb_3k_timestamped_contexts_memory	memory utilization	+0.22	[+0.01, +0.43]	1	Logs
➖	quality_gate_security_mean_fs_load	memory utilization	+0.07	[+0.03, +0.11]	1	Logs bounds checks dashboard
➖	quality_gate_security_idle	memory utilization	-0.07	[-0.12, -0.02]	1	Logs bounds checks dashboard
➖	dsd_uds_10mb_3k_timestamped_contexts_cpu	% cpu utilization	-0.08	[-0.32, +0.16]	1	Logs
➖	quality_gate_idle	memory utilization	-0.12	[-0.16, -0.08]	1	Logs bounds checks dashboard
➖	quality_gate_idle_all_features	memory utilization	-0.29	[-0.33, -0.25]	1	Logs bounds checks dashboard
➖	quality_gate_metrics_logs	memory utilization	-0.35	[-0.58, -0.12]	1	Logs bounds checks dashboard
➖	quality_gate_private_action_runner	memory utilization	-0.74	[-0.85, -0.62]	1	Logs bounds checks dashboard
➖	quality_gate_logs	% cpu utilization	-2.30	[-3.15, -1.45]	1	Logs bounds checks dashboard

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	observed_value	links
✅	quality_gate_idle	intake_connections	10/10	4 = 4	bounds checks dashboard
✅	quality_gate_idle	memory_usage	10/10	173.71MiB ≤ 179MiB	bounds checks dashboard
✅	quality_gate_idle	total_bytes_received	10/10	752.23KiB ≤ 819.20KiB	bounds checks dashboard
✅	quality_gate_idle_all_features	intake_connections	10/10	4 = 4	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	523.80MiB ≤ 537MiB	bounds checks dashboard
✅	quality_gate_idle_all_features	total_bytes_received	10/10	1.14MiB ≤ 1.25MiB	bounds checks dashboard
✅	quality_gate_logs	intake_connections	10/10	19 ≤ 40	bounds checks dashboard
✅	quality_gate_logs	memory_usage	10/10	210.64MiB ≤ 220MiB	bounds checks dashboard
✅	quality_gate_logs	missed_bytes	10/10	0B = 0B	bounds checks dashboard
✅	quality_gate_logs	total_bytes_received	10/10	263.08MiB ≤ 292MiB	bounds checks dashboard
✅	quality_gate_metrics_logs	cpu_usage	10/10	369.45 ≤ 2000	bounds checks dashboard
✅	quality_gate_metrics_logs	intake_connections	10/10	20 ≤ 40	bounds checks dashboard
✅	quality_gate_metrics_logs	memory_usage	10/10	418.37MiB ≤ 455MiB	bounds checks dashboard
✅	quality_gate_metrics_logs	missed_bytes	10/10	0B = 0B	bounds checks dashboard
✅	quality_gate_metrics_logs	total_bytes_received	10/10	0.94GiB ≤ 1.04GiB	bounds checks dashboard
✅	quality_gate_private_action_runner	memory_usage	10/10	72.32MiB ≤ 75MiB	bounds checks dashboard
✅	quality_gate_security_idle	cpu_usage	10/10	28.77 ≤ 100	bounds checks dashboard
✅	quality_gate_security_idle	memory_usage	10/10	322.96MiB ≤ 355MiB	bounds checks dashboard
✅	quality_gate_security_mean_fs_load	cpu_usage	10/10	60.03 ≤ 200	bounds checks dashboard
✅	quality_gate_security_mean_fs_load	memory_usage	10/10	302.67MiB ≤ 335MiB	bounds checks dashboard
✅	quality_gate_security_no_fs_load	cpu_usage	10/10	22.51 ≤ 100	bounds checks dashboard
✅	quality_gate_security_no_fs_load	memory_usage	10/10	310.89MiB ≤ 345MiB	bounds checks dashboard

Explanation

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

CI Pass/Fail Decision

✅ Passed. All Quality Gates passed.

• quality_gate_idle, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check missed_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_private_action_runner, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_mean_fs_load, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_mean_fs_load, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_idle, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_no_fs_load, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_no_fs_load, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check missed_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.