feat(otlphttp): configure response body size limit by AbhiPrasad · Pull Request #8443 · open-telemetry/opentelemetry-go

AbhiPrasad · 2026-06-09T19:13:42Z

Add WithMaxResponseBodySize to the OTLP/HTTP trace, metric, and log exporters so users can tune the response body size limit while preserving the 4 MiB default.

otlptracehttp.WithMaxResponseBodySize(size int64)
otlpmetrichttp.WithMaxResponseBodySize(size int64)
otlploghttp.WithMaxResponseBodySize(size int64)

Example:

exp, err := otlptracehttp.New(
	otlptracehttp.WithMaxResponseBodySize(8 * 1024 * 1024),
)

Passing a size less than or equal to zero disables the response body size limit:

exp, err := otlptracehttp.New(
	otlptracehttp.WithMaxResponseBodySize(0),
)

This follows open-telemetry/opentelemetry-proto#802, which made client response limits configurable: open-telemetry/opentelemetry-proto#802

The OTLP/HTTP specification requires clients to limit response body size and says implementations SHOULD allow the limit to be configured: https://github.com/open-telemetry/opentelemetry-proto/blob/41ad255e3efd5450096fc167ef6d87edb4bcb4f3/docs/specification.md#L522-L525

codecov · 2026-06-09T19:17:21Z

Codecov Report

❌ Patch coverage is 86.95652% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.9%. Comparing base (dde00d9) to head (c8bd6a5).
⚠️ Report is 113 commits behind head on main.

Files with missing lines	Patch %	Lines
exporters/otlp/otlplog/otlploghttp/client.go	84.6%	2 Missing and 2 partials ⚠️
exporters/otlp/otlpmetric/otlpmetrichttp/client.go	83.3%	2 Missing and 2 partials ⚠️
exporters/otlp/otlptrace/otlptracehttp/client.go	76.4%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #8443   +/-   ##
=====================================
  Coverage   83.9%   83.9%           
=====================================
  Files        323     323           
  Lines      25814   25867   +53     
=====================================
+ Hits       21676   21724   +48     
+ Misses      3758    3757    -1     
- Partials     380     386    +6

Files with missing lines	Coverage Δ
exporters/otlp/otlplog/otlploghttp/config.go	`94.3% <100.0%> (+0.1%)`	⬆️
...tlpmetric/otlpmetricgrpc/internal/oconf/options.go	`90.3% <100.0%> (ø)`
exporters/otlp/otlpmetric/otlpmetrichttp/config.go	`89.1% <100.0%> (+0.6%)`	⬆️
...tlpmetric/otlpmetrichttp/internal/oconf/options.go	`93.6% <100.0%> (+0.2%)`	⬆️
...trace/otlptracegrpc/internal/otlpconfig/options.go	`94.1% <100.0%> (ø)`
...trace/otlptracehttp/internal/otlpconfig/options.go	`93.1% <100.0%> (+0.2%)`	⬆️
exporters/otlp/otlptrace/otlptracehttp/options.go	`100.0% <100.0%> (ø)`
exporters/otlp/otlplog/otlploghttp/client.go	`87.4% <84.6%> (-0.2%)`	⬇️
exporters/otlp/otlpmetric/otlpmetrichttp/client.go	`86.8% <83.3%> (-0.4%)`	⬇️
exporters/otlp/otlptrace/otlptracehttp/client.go	`84.5% <76.4%> (-0.3%)`	⬇️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

pellared · 2026-06-09T19:29:35Z

Code generation fails https://github.com/open-telemetry/opentelemetry-go/actions/runs/27229699243/job/80406249310?pr=8443

Copilot

Pull request overview

This PR adds a configurable response body size limit for the OTLP/HTTP trace, metric, and log exporters, preserving the existing 4 MiB default while allowing users to tune it (including disabling the limit with size <= 0) in line with OTLP/HTTP spec guidance.

Changes:

Introduces WithMaxResponseBodySize(int64) in OTLP/HTTP trace/metric/log exporters and wires it through each exporter’s HTTP config.
Replaces the prior package-level response size limit variables with per-client config and a shared copyResponseBody helper to enforce/disable the limit.
Updates response-body-size-limit tests to use the new option and documents the new options in CHANGELOG.md.

Reviewed changes

Copilot reviewed 17 out of 21 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
internal/shared/otlp/otlptrace/otlpconfig/options.go.tmpl	Adds HTTP-only default/config field + option for max response body size in shared trace config template.
internal/shared/otlp/otlpmetric/oconf/options.go.tmpl	Adds HTTP-only default/config field + option for max response body size in shared metric config template.
exporters/otlp/otlptrace/otlptracehttp/options.go	Exposes `WithMaxResponseBodySize` as a public trace HTTP exporter option.
exporters/otlp/otlptrace/otlptracehttp/internal/otlpconfig/options.go	Generated trace HTTP config now includes `MaxResponseBodySize` default + option plumbing.
exporters/otlp/otlptrace/otlptracehttp/internal/gen.go	Passes `isHTTP` to templates to conditionally generate HTTP-only settings.
exporters/otlp/otlptrace/otlptracehttp/export_test.go	Removes prior test-only export of the package-level response limit override.
exporters/otlp/otlptrace/otlptracehttp/client.go	Enforces response body size via config (`MaxResponseBodySize`) and adds `copyResponseBody` helper with disable support.
exporters/otlp/otlptrace/otlptracehttp/client_test.go	Updates response body size limit test to use `WithMaxResponseBodySize(1)` instead of global override.
exporters/otlp/otlptrace/otlptracegrpc/internal/otlpconfig/options.go	Regenerates gRPC trace config from templates (no response-size setting for non-HTTP).
exporters/otlp/otlptrace/otlptracegrpc/internal/gen.go	Passes `isHTTP: false` to templates for gRPC trace exporter generation.
exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/options.go	Generated metric HTTP config now includes `MaxResponseBodySize` default + option plumbing.
exporters/otlp/otlpmetric/otlpmetrichttp/internal/gen.go	Passes `isHTTP` to metric templates to conditionally generate HTTP-only settings.
exporters/otlp/otlpmetric/otlpmetrichttp/config.go	Exposes `WithMaxResponseBodySize` as a public metric HTTP exporter option.
exporters/otlp/otlpmetric/otlpmetrichttp/client.go	Enforces response body size via config and adds `copyResponseBody` helper with disable support.
exporters/otlp/otlpmetric/otlpmetrichttp/client_test.go	Updates response body size limit test to use `WithMaxResponseBodySize(1)` instead of global override.
exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/options.go	Regenerates gRPC metric config from templates (no response-size setting for non-HTTP).
exporters/otlp/otlpmetric/otlpmetricgrpc/internal/gen.go	Passes `isHTTP: false` to templates for gRPC metric exporter generation.
exporters/otlp/otlplog/otlploghttp/config.go	Adds log HTTP exporter config setting + `WithMaxResponseBodySize` option (non-templated config).
exporters/otlp/otlplog/otlploghttp/client.go	Enforces response body size via config and adds `copyResponseBody` helper with disable support.
exporters/otlp/otlplog/otlploghttp/client_test.go	Updates response body size limit test to use `WithMaxResponseBodySize(1)` instead of global override.
CHANGELOG.md	Documents the newly added `WithMaxResponseBodySize` options for trace/metric/log HTTP exporters.

Files not reviewed (4)

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/options.go: Language not supported
exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/options.go: Language not supported
exporters/otlp/otlptrace/otlptracegrpc/internal/otlpconfig/options.go: Language not supported
exporters/otlp/otlptrace/otlptracehttp/internal/otlpconfig/options.go: Language not supported

pellared · 2026-06-12T09:48:21Z

@AbhiPrasad, are you able to address comments or do you want me to take over?

AbhiPrasad · 2026-06-12T16:08:14Z

@AbhiPrasad, are you able to address comments or do you want me to take over?

sorry for the delay, my day job got in the way 😄

Pushed up commits to address the review changes!

Copilot

Pull request overview

Copilot reviewed 17 out of 21 changed files in this pull request and generated 6 comments.

Files not reviewed (4)

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/options.go: Generated file
exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/options.go: Generated file
exporters/otlp/otlptrace/otlptracegrpc/internal/otlpconfig/options.go: Generated file
exporters/otlp/otlptrace/otlptracehttp/internal/otlpconfig/options.go: Generated file

pellared · 2026-06-12T16:32:40Z

@AbhiPrasad, I agree with Copilot 😉 Can you address the comments when you find some time?

AbhiPrasad · 2026-06-12T16:50:01Z

I agree as well! pushed up the fix with cf9968e

Copilot

Pull request overview

Copilot reviewed 17 out of 21 changed files in this pull request and generated 5 comments.

Files not reviewed (4)

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/options.go: Generated file
exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/options.go: Generated file
exporters/otlp/otlptrace/otlptracegrpc/internal/otlpconfig/options.go: Generated file
exporters/otlp/otlptrace/otlptracehttp/internal/otlpconfig/options.go: Generated file

pellared · 2026-07-02T12:04:58Z

@AbhiPrasad, build is failing. Can you please take a look?

Add WithMaxResponseBodySize to the OTLP/HTTP trace, metric, and log exporters so users can tune the response body size limit while preserving the 4 MiB default. ```go otlptracehttp.WithMaxResponseBodySize(size int64) otlpmetrichttp.WithMaxResponseBodySize(size int64) otlploghttp.WithMaxResponseBodySize(size int64) ``` Example: ```go exp, err := otlptracehttp.New( otlptracehttp.WithMaxResponseBodySize(8 * 1024 * 1024), ) ``` Passing a size less than or equal to zero disables the response body size limit: ```go exp, err := otlptracehttp.New( otlptracehttp.WithMaxResponseBodySize(0), ) ``` This follows open-telemetry/opentelemetry-proto#802, which made client response limits configurable: open-telemetry/opentelemetry-proto#802 The OTLP/HTTP specification requires clients to limit response body size and says implementations SHOULD allow the limit to be configured: https://github.com/open-telemetry/opentelemetry-proto/blob/41ad255e3efd5450096fc167ef6d87edb4bcb4f3/docs/specification.md#L522-L525

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated no new comments.

pellared · 2026-07-09T12:28:09Z

@open-telemetry/go-approvers, this needs more reviews and approval(s)

MrAlias

Before we add this API to three modules, can we establish the concrete use case? The specification's SHOULD is a reason to consider configurability, but the PR does not link a Go issue or describe a legitimate response that exceeds the existing 4 MiB limit. Is there a user who needs to raise or lower this value, or are we treating the SHOULD as sufficient reason to add the permanent API surface?

MrAlias · 2026-07-09T16:35:02Z

+// WithMaxResponseBodySize sets the maximum size, in bytes, of the response body
+// (after decompression) that the exporter will read.
+//
+// If size is less than or equal to zero, no response body size limit is applied.


The OTLP/HTTP specification says clients MUST limit response-body size to protect against excessive memory use from a misconfigured or malicious server. With size <= 0, each exporter performs an unbounded io.Copy into a bytes.Buffer, so a collector can exhaust the application's memory.

This option can remain configurable, but every configuration needs to retain a finite positive limit. Please treat non-positive values as invalid or keep the 4 MiB default instead of disabling the limit. The same applies to the math.MaxInt64 unlimited path in each exporter.

dashpole · 2026-07-09T19:25:50Z

I generally view SHOULD as meaning we should add something unless we have a good reason not to. I could definitely see lowering the value as something I might want to do if large responses were causing problems.

pellared

Please address #8443 (comment)

MrAlias · 2026-08-11T15:15:59Z

@AbhiPrasad please address the remaining unresolved thread and current changes-requested review.

dashpole · 2026-08-13T13:43:38Z

 	req.Header.Set("Content-Type", "application/x-protobuf")

+	maxResponseBodySize := defaultMaxResponseBodySize
+	if cfg.maxResponseBodySize.Set {


Could we resolve c.maxResponseBodySize with fallback[int64](defaultMaxResponseBodySize) in newConfig (like maxRequestSize), so we can pass cfg.maxResponseBodySize.Value directly here without manual checking?

AbhiPrasad requested review from MrAlias, XSAM, dashpole, dmathieu, flc1125 and pellared as code owners June 9, 2026 19:13

pellared requested a review from Copilot June 10, 2026 14:21

Copilot started reviewing on behalf of pellared June 10, 2026 14:21 View session

Copilot AI reviewed Jun 10, 2026

View reviewed changes

Comment thread exporters/otlp/otlptrace/otlptracehttp/client.go Outdated

Comment thread exporters/otlp/otlpmetric/otlpmetrichttp/client.go Outdated

Comment thread exporters/otlp/otlplog/otlploghttp/client.go Outdated

pellared reviewed Jun 10, 2026

View reviewed changes

Comment thread exporters/otlp/otlplog/otlploghttp/client.go Outdated

pellared reviewed Jun 10, 2026

View reviewed changes

Comment thread exporters/otlp/otlplog/otlploghttp/config.go Outdated

pellared requested a review from Copilot June 12, 2026 16:24

Copilot started reviewing on behalf of pellared June 12, 2026 16:25 View session

Copilot AI reviewed Jun 12, 2026

View reviewed changes

pellared requested a review from Copilot June 12, 2026 17:40

Copilot started reviewing on behalf of pellared June 12, 2026 17:40 View session

Copilot AI reviewed Jun 12, 2026

View reviewed changes

pellared added this to the v1.45.0 milestone Jul 2, 2026

AbhiPrasad added 5 commits July 2, 2026 14:38

fix: keep OTLP response size config HTTP-only

8169d3f

fix(otlphttp): limit response bodies without MaxBytesReader

9df4221

test(otlphttp): cover disabled response body limit

8b173cc

docs(otlphttp): clarify response body size option

8bf0d7b

AbhiPrasad and others added 3 commits July 2, 2026 14:38

fix(otlphttp): avoid response body limit overflow

628bc01

Apply suggestions from code review

fd8962f

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

chore: update generated OTLP config

5a23b9e

AbhiPrasad force-pushed the abhi-feat-otlp-response-body-limit branch from 8cfe8b7 to 5a23b9e Compare July 2, 2026 18:44

pellared reviewed Jul 2, 2026

View reviewed changes

Comment thread internal/shared/otlp/otlpmetric/oconf/options.go.tmpl Outdated

chore: format OTLP config templates

23dab0a

AbhiPrasad force-pushed the abhi-feat-otlp-response-body-limit branch from 9ba2a00 to 23dab0a Compare July 6, 2026 15:40

Merge branch 'main' into abhi-feat-otlp-response-body-limit

c8bd6a5

pellared requested a review from Copilot July 9, 2026 12:15

Copilot started reviewing on behalf of pellared July 9, 2026 12:16 View session

Copilot AI reviewed Jul 9, 2026

View reviewed changes

pellared approved these changes Jul 9, 2026

View reviewed changes

MrAlias reviewed Jul 9, 2026

View reviewed changes

pellared requested changes Jul 15, 2026

View reviewed changes

MrAlias modified the milestones: v1.45.0, v1.46.0 Jul 23, 2026

coderabbitai Bot mentioned this pull request Aug 4, 2026

ci(renovate): fix lookup failures found by debug run + config audit enix/x509-certificate-exporter#673

Merged

MrAlias added the response needed Waiting on user input before progress can be made label Aug 11, 2026

dashpole reviewed Aug 13, 2026

View reviewed changes

Uh oh!

Conversation

AbhiPrasad commented Jun 9, 2026

Uh oh!

codecov Bot commented Jun 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

pellared commented Jun 9, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

pellared commented Jun 12, 2026

Uh oh!

AbhiPrasad commented Jun 12, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

pellared commented Jun 12, 2026

Uh oh!

AbhiPrasad commented Jun 12, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

pellared commented Jul 2, 2026

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

pellared commented Jul 9, 2026

Uh oh!

MrAlias left a comment

Choose a reason for hiding this comment

Uh oh!

MrAlias Jul 9, 2026

Choose a reason for hiding this comment

Uh oh!

pellared Jul 15, 2026

Choose a reason for hiding this comment

Uh oh!

dashpole commented Jul 9, 2026

Uh oh!

pellared left a comment

Choose a reason for hiding this comment

Uh oh!

MrAlias commented Aug 11, 2026

Uh oh!

dashpole Aug 13, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

codecov Bot commented Jun 9, 2026 •

edited

Loading