[NO-TICKET] ActionController - Honor resource override

[vpellan]

What does this PR do?

Honor resource override in ActionController

Motivation:

Internal support

Change log entry

Yes. Preserve custom trace resource names for ActionController requests.

Additional Notes:

How to test the change?

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-03T14:24:45.998111Z	0aa1612	PR opened
🔒 Security Review	✅ Completed 2026-09-03T14:25:48.658520Z	0aa1612	PR opened

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[datadog-official]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 90.32% (+0.01%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 0aa1612 | Docs | View more details | Give us feedback!}

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-09-03 15:12:35

Comparing candidate commit 0aa1612 in PR branch vpellan/active-record-honor-resource-override with baseline commit 0198684 in branch master.

📊 Benchmarking dashboard

Found 0 performance improvements and 0 performance regressions! Performance is the same for 51 metrics, 1 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

Unstable benchmarks

These benchmarks have a confidence interval too wide to call a change; treat them as noise rather than signal.

scenario:tracing - Tracing.continue_trace!

• unstable throughput [-1334.296op/s; +2561.446op/s] or [-3.501%; +6.720%]

[mabdinur]

Could we also treat !trace.resource_override? as eligible here? TraceOperation defines trace.resource = nil as clearing the override, but this equality then fails and Rack falls back to its generic resource.
A small spec for that transition plus !trace.resource_override? || ... would preserve the existing no-override behavior.

[mabdinur]

The resource-ownership approach matches the existing Rack precedence, and the tests cover overrides both before controller start and during request processing. I left one non-blocking edge-case note.

[TonyCTHsu]

1. The pull request description does not explain why.
2. Changing resource has been risky because of backward compatibility, please elaborate how this change impact customers.