[soujasK]

Issue number: closes #8667

Summary

Changes

POWERTOOLS_METRICS_DISABLED (added in #6046 for both providers) was only checked in flush_metrics(). This adds the same is_metrics_disabled() check to the other emission paths:

• single_metric (metrics/base.py): only prints when metrics aren't disabled. This also covers the CloudWatch ColdStart metric, which is emitted through single_metric. It also no longer prints a null line when the with body raises (metric_set is still None at that point); the exception still propagates.
• AmazonCloudWatchEMFProvider.add_metric: the automatic flush at 100 metrics / 100 values doesn't print when disabled. The metric set is still cleared, as before.
• DatadogProvider.flush_metrics: doesn't submit through datadog_lambda's lambda_metric when disabled.

Since is_metrics_disabled() also returns true for POWERTOOLS_DEV=true without POWERTOOLS_METRICS_DISABLED, single_metric and the cold start metric are now silent in dev mode too, the same as flush_metrics() already was.

The legacy MetricManager in metrics/base.py isn't changed: it's only reached through SingleMetric, which can't hit its auto-flush.

Tests: one per path (single_metric, cold start via log_metrics, the 100-metric auto-flush, Datadog lambda_metric mocked), a POWERTOOLS_DEV case for single_metric, and the null line when the body raises. The five path tests fail without the change. tests/functional/metrics passes; on Linux (Python 3.12) ruff, mypy, ty, bandit and xenon pass. Running tests/unit, tests/functional/metrics and tests/functional/batch together on Linux, test_datadog_write_to_log_with_env_variable fails the same way on develop without this change (it passes on its own), so it looks like existing cross-test state.

User experience

Before: with metrics disabled, the ColdStart metric, single_metric, the 100-metric auto-flush and Datadog extension submissions were still emitted (and EMF lines are ingested by CloudWatch).

After: nothing is emitted when metrics are disabled.

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[leandrodamascena]

Hi @soujasK, I saw you closed this one. No problem, I just want to understand what you'd prefer. The bug is real and triaged for 3.40.0, and I already worked on it on my side. Do you want to reopen so I review your PR, or should I open a new one myself? Either way is fine, just let me know.

[soujasK]

Reopening this. I closed it by mistake. I need a bit more time to test and validate it properly, so I'll update here once that's done.

[leandrodamascena]

Thanks @soujasK, same story as #8664, this missed 3.40.0 and goes in 3.41.0. The change is right and the six tests cover every path. It overlaps with #8797, which touches the same lines in single_metric, so once that one lands I'll resolve the conflict on your branch myself rather than asking you to. You'll be in the release notes.

[leandrodamascena]

Thanks @soujasK! Reviewed on top of develop with #8797 in: every emission path now checks the flag, including the cold start metric and the Datadog submit, and the six tests cover them. I merged develop into your branch to clear the one-line overlap with #8797, nothing else changed. Goes out in 3.41.0, you'll be in the release notes.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.17%. Comparing base (ff823e7) to head (e390e86).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8668   +/-   ##
========================================
  Coverage    97.17%   97.17%           
========================================
  Files          323      323           
  Lines        16629    16630    +1     
  Branches      1509     1510    +1     
========================================
+ Hits         16160    16161    +1     
  Misses         328      328           
  Partials       141      141           

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