Add optional http.client.response.body.size span attribute & metric to Aiohttp-client instrumentation. by weizhikuan · Pull Request #4572 · open-telemetry/opentelemetry-python-contrib

weizhikuan · 2026-05-12T03:34:27Z

Description

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Fixes #3623

Type of change

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Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected)
This change requires a documentation update

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Added unit tests.

Does This PR Require a Core Repo Change?

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No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

Followed the style guidelines of this project
Changelogs have been updated
Unit tests have been added
Documentation has been updated

weizhikuan · 2026-05-12T03:43:14Z

As per the semconv spec v1.41.0, the span attribute and metric are both optional. So I added both of them and only enabled when semconv stability contains http and the env var OTEL_PYTHON_INSTRUMENTATION_HTTP_RESPONSE_BODY_SIZE is set as true.

emdneto · 2026-05-12T23:15:01Z

Thanks for the PR!

Just a heads-up: we no longer update CHANGELOG.md directly. The changelog is now generated from changelog fragments using Towncrier.

Please add the appropriate changelog fragment for this change instead of editing CHANGELOG.md manually. You can find the instructions and expected format in CONTRIBUTING.md.

tammy-baylis-swi · 2026-05-13T23:34:34Z

Thank you for this @weizhikuan . The way to opt into this makes sense. Please do a quick tox -e precommit to fix some formatting.

weizhikuan · 2026-05-14T14:07:09Z

Thanks for the PR!

Just a heads-up: we no longer update CHANGELOG.md directly. The changelog is now generated from changelog fragments using Towncrier.

Please add the appropriate changelog fragment for this change instead of editing CHANGELOG.md manually. You can find the instructions and expected format in CONTRIBUTING.md.

Gotcha, will add the fragment.

herin049 · 2026-05-17T18:28:06Z

+****************************
+To capture the ``http.response.body.size`` span attribute and record the
+``http.client.response.body.size`` metric histogram, set the environment variable
+``OTEL_PYTHON_INSTRUMENTATION_HTTP_RESPONSE_BODY_SIZE`` to ``"true"``.


Personally, I don't think that having an opt-in is really needed here. From my understanding, when the Spec states that a metric or attribute is "optional", it usually indicates that library authors can optionally add it - not necessarily that users need the ability to enable/disable it. Typically, the spec will explicitly state if behavior should be opt-in only.

Same understanding here.

So... this is suggesting removing the env var and have this enabled directly? But this is what I get from the spec for the definition of 'Opt-In' level requirement, which sounds requesting such attribute cannot be emitted if user s did not explicitly enable.

herin049 · 2026-05-17T18:41:44Z

        ):
            return

        trace_config_ctx.start_time = default_timer()


We should probably add the following, just to ensure that the response body size doesn't accidentally leak into another request (e.g. if follow-up requests don't end up setting the attribute)

Suggested change

trace_config_ctx.start_time = default_timer()

trace_config_ctx.response_body_size = None

Thanks for pointing this out. Just trying to understand the issue better. From my understanding, the aiohttp will create a new trace_config_ctx per request via the factory function. Why and how could it gets leaked to another request?

github-actions · 2026-06-03T04:48:14Z

This PR has been automatically marked as stale because it has not had any activity for 14 days. It will be closed if no further activity occurs within 14 days of this comment.
If you're still working on this, please add a comment or push new commits.

weizhikuan · 2026-06-04T15:11:29Z

Hello @herin049, may I get another look for the review comment discussion? Thanks!

github-actions · 2026-06-19T04:48:32Z

This PR has been automatically marked as stale because it has not had any activity for 14 days. It will be closed if no further activity occurs within 14 days of this comment.
If you're still working on this, please add a comment or push new commits.

github-actions · 2026-07-05T04:36:16Z

This PR has been automatically marked as stale because it has not had any activity for 14 days. It will be closed if no further activity occurs within 14 days of this comment.
If you're still working on this, please add a comment or push new commits.

github-actions · 2026-07-20T04:26:16Z

This PR has been closed due to inactivity. Please reopen if you would like to continue working on it.

Copilot

Pull request overview

This PR extends opentelemetry-instrumentation-aiohttp-client to optionally emit the new HTTP semantic convention response body size signal: it sets the http.response.body.size span attribute and records the http.client.response.body.size histogram metric when explicitly enabled via an environment variable (and when new HTTP semconv is active).

Changes:

Add a shared util-http env var toggle (OTEL_PYTHON_INSTRUMENTATION_HTTP_RESPONSE_BODY_SIZE) and helper to check it.
In aiohttp-client instrumentation, when enabled + new semconv active, populate http.response.body.size from Content-Length and record the http.client.response.body.size metric.
Add integration tests covering default-off behavior, enabled behavior, and semconv gating; add a changelog entry.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
util/opentelemetry-util-http/src/opentelemetry/util/http/init.py	Adds env var constant + helper to opt-in to response body size capture.
instrumentation/opentelemetry-instrumentation-aiohttp-client/src/opentelemetry/instrumentation/aiohttp_client/init.py	Implements optional `http.response.body.size` span attribute + `http.client.response.body.size` metric recording based on `Content-Length`.
instrumentation/opentelemetry-instrumentation-aiohttp-client/tests/test_aiohttp_client_integration.py	Adds tests for span attribute presence/default-off, semconv gating, and metric emission when enabled.
.changelog/4572.added	Documents the new optional span attribute + metric for aiohttp-client instrumentation.

@@ -0,0 +1 @@
+`opentelemetry-instrumentation-aiohttp-client`: add optional `http.client.response.body.size` span attribute & metric to the aiohttp client instrumentation


+        span = self._assert_spans(1)
+        self.assertIn(HTTP_RESPONSE_BODY_SIZE, span.attributes)
+        self.assertIsInstance(span.attributes[HTTP_RESPONSE_BODY_SIZE], int)
+


+        run_with_test_server(
+            self.get_default_request(), self.URL, self.handler_with_body
+        )
+        metrics = self._assert_metrics(2)
+        metric_names = {m.name for m in metrics}
+        self.assertIn("http.client.response.body.size", metric_names)
+        body_size_metric = next(
+            m for m in metrics if m.name == "http.client.response.body.size"
+        )
+        data_point = body_size_metric.data.data_points[0]
+        self.assertEqual(data_point.count, 1)
+        self.assertTrue(data_point.sum > 0)
+


weizhikuan requested a review from a team as a code owner May 12, 2026 03:34

github-actions Bot assigned herin049 May 12, 2026

github-actions Bot requested a review from herin049 May 12, 2026 03:34

otelbot-python Bot added this to Python PR digest May 12, 2026

weizhikuan force-pushed the i3623 branch from cfd7534 to 7ca0947 Compare May 14, 2026 14:06

aabmass moved this to Ready for review in Python PR digest May 14, 2026

herin049 reviewed May 17, 2026

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herin049 moved this from Ready for review to Reviewed PRs that need fixes in Python PR digest May 17, 2026

herin049 reviewed May 17, 2026

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weizhikuan requested a review from herin049 May 20, 2026 03:34

github-actions Bot added the Stale label Jun 3, 2026

weizhikuan added 5 commits June 4, 2026 11:11

add opt-in response body size span attribute + metric

acc18b0

add unit tests

aa5df6d

fix format

9387b01

add changelog fragment

af2c369

add handler with response body to unit tests

aec8fe5

weizhikuan force-pushed the i3623 branch from 96c2a4b to aec8fe5 Compare June 4, 2026 15:12

github-actions Bot removed the Stale label Jun 5, 2026

github-actions Bot added the Stale label Jun 19, 2026

Merge branch 'main' into i3623

118166c

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github-project-automation Bot moved this from Reviewed PRs that need fixes to Done in Python PR digest Jul 20, 2026

aabmass reopened this Aug 3, 2026

aabmass requested a review from Copilot August 3, 2026 20:51

Copilot started reviewing on behalf of aabmass August 3, 2026 20:52 View session

Copilot AI reviewed Aug 3, 2026

View reviewed changes


	trace_config_ctx.start_time = default_timer()
	trace_config_ctx.response_body_size = None

		@@ -0,0 +1 @@
		`opentelemetry-instrumentation-aiohttp-client`: add optional `http.client.response.body.size` span attribute & metric to the aiohttp client instrumentation

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weizhikuan commented May 12, 2026

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weizhikuan commented May 12, 2026 •

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