Implement non-utf8 string to bytes in OTLP exporters. by owent · Pull Request #3991 · open-telemetry/opentelemetry-cpp

owent · 2026-04-12T15:54:55Z

Changes

Mapping non UTF8 string to bytes in OLTP exporters.

https://github.com/open-telemetry/opentelemetry-specification/blame/v1.55.0/specification/common/attribute-type-mapping.md.
Reimplement #3512 to meet the latest spec.

For significant contributions please make sure you have completed the following items:

CHANGELOG.md updated for non-trivial changes
Unit tests have been added
Changes in public API reviewed

Copilot

Pull request overview

This PR updates the OTLP exporter attribute/value population logic to validate UTF-8 for string-like inputs and encode non-UTF8 values as bytes_value, aligning exporter output with the latest spec’s non-UTF8 mapping guidance. It also introduces a protobuf-sourced UTF-8 validation dependency to support this conversion in both CMake and Bazel builds.

Changes:

Add UTF-8 validation in OtlpPopulateAttributeUtils and convert invalid string inputs to bytes_value.
Remove the allow_bytes parameter from PopulateAnyValue/PopulateAttribute and update all call sites accordingly.
Add a new UTF-8 validity dependency wiring for OTLP (CMake + Bazel) and update OTLP log recordable tests.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
exporters/otlp/src/otlp_populate_attribute_utils.cc	Adds UTF-8 validation and maps invalid strings to `bytes_value`; updates array-string handling similarly.
exporters/otlp/include/opentelemetry/exporters/otlp/otlp_populate_attribute_utils.h	Updates public helper signatures to remove `allow_bytes`.
exporters/otlp/src/otlp_log_recordable.cc	Updates log body/attribute population calls to new helper signatures.
exporters/otlp/src/otlp_recordable.cc	Updates span attribute/event/link attribute population calls to new helper signatures.
exporters/otlp/src/otlp_metric_utils.cc	Updates metric point attribute population calls to new helper signatures.
exporters/otlp/test/otlp_log_recordable_test.cc	Updates tests to assert non-UTF8 `string_view` becomes `bytes_value`.
exporters/otlp/CMakeLists.txt	Adds protobuf-sourced `utf8_range`/validity library integration and links OTLP recordable against it.
exporters/otlp/BUILD	Adds a Bazel helper library to bring in protobuf’s utf8_range/utf8_validity deps and wires it into `otlp_recordable`.

Comments suppressed due to low confidence (1)

exporters/otlp/CMakeLists.txt:149

opentelemetry_otlp_recordable now links against ${OPENTELEMETRY_OTLP_DEP_UTF8_VALIDITY}, but the generated otlp_recordable pkg-config module doesn’t list a corresponding Requires: entry. This can break pkg-config consumers at link time (missing -lopentelemetry_otlp_utf8_validity when the bundled target is used). Consider conditionally adding opentelemetry_otlp_utf8_validity to the opentelemetry_add_pkgconfig(otlp_recordable, ...) requires list when that target is built.

  opentelemetry_add_pkgconfig(
    otlp_recordable
    "OpenTelemetry OTLP - Recordable"
    "OTLP recordable implementation for spans, metrics, and logs."
    "opentelemetry_trace opentelemetry_metrics opentelemetry_logs opentelemetry_resources"
  )

codecov · 2026-04-12T16:17:09Z

Codecov Report

❌ Patch coverage is 80.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.06%. Comparing base (dbf6567) to head (bc87985).

Files with missing lines	Patch %	Lines
...xporters/otlp/src/otlp_populate_attribute_utils.cc	80.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3991      +/-   ##
==========================================
+ Coverage   82.06%   82.06%   +0.01%     
==========================================
  Files         385      385              
  Lines       15891    15900       +9     
==========================================
+ Hits        13039    13047       +8     
- Misses       2852     2853       +1

Files with missing lines	Coverage Δ
...xporters/otlp/src/otlp_populate_attribute_utils.cc	`92.91% <80.00%> (-1.78%)`	⬇️

... 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.

dbarker

Thanks for the feature @owent! Please see my comments below.

dbarker

Looks good. Thanks for the feature. Please see a few minor cleanup questions below.

marcalff

Thanks for the PR.

This PR actually implements the specification, which should be a good thing in general.

In this particular case, and this is an opinion, the spec is a bad idea.

Please consider to add an option to opt-out and not add this extra UTF-8 validation, for applications that are instrumented correctly (strings are string, bytes sequences are binary), which do not need the overhead.

marcalff · 2026-04-20T20:31:00Z

+    }
+    else
+    {
+      proto_value->set_bytes_value(str_value, strlen(str_value));


Here, strlen means the instrumented application can send binary in a string, as long as the binary does not contains a nul character ...

A properly instrumented application will need to provide a sequence of bytes instead of a string anyway, to work properly.

But this change (which faithfully implement the specs) makes every application slower, due to the added UTF-8 validation, to try to accommodate poorly instrumented applications using the wrong types.

We receive a const char* that we assume is null-terminated, but it may contain invalid UTF-8.

Should include <cstring> for strlen then?

ThomsonTan

Consider add a CHANGELOG entry for this feature work.

https://github.com/open-telemetry/opentelemetry-specification/blame/v1.55.0/specification/common/attribute-type-mapping.md

…ory.

Copilot AI review requested due to automatic review settings April 12, 2026 15:55

owent requested a review from a team as a code owner April 12, 2026 15:55

Copilot started reviewing on behalf of owent April 12, 2026 15:55 View session

owent mentioned this pull request Apr 12, 2026

Add bundle version of utf8_range to validate attributes #3512

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5 tasks

owent force-pushed the validate_utf8_string_in_otlp branch from 2299799 to f66b834 Compare April 12, 2026 15:58

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Comment thread exporters/otlp/src/otlp_populate_attribute_utils.cc Outdated

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lalitb reviewed Apr 13, 2026

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owent changed the title ~~Implement non-utf8 string to bytes in OTLP exporters.~~ [WIP] Implement non-utf8 string to bytes in OTLP exporters. Apr 18, 2026

owent force-pushed the validate_utf8_string_in_otlp branch 2 times, most recently from 4ba4995 to 5de988c Compare April 18, 2026 13:52

owent changed the title ~~[WIP] Implement non-utf8 string to bytes in OTLP exporters.~~ Implement non-utf8 string to bytes in OTLP exporters. Apr 19, 2026

dbarker approved these changes Apr 20, 2026

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Comment thread cmake/protobuf.cmake

Comment thread exporters/otlp/CMakeLists.txt Outdated

marcalff reviewed Apr 20, 2026

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marcalff mentioned this pull request Apr 21, 2026

[RELEASE] Release opentelemetry-cpp v1.27.0 #4017

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owent added 3 commits April 26, 2026 16:30

Implement non-utf8 string to bytes in OTLP exporters.

87c085e

https://github.com/open-telemetry/opentelemetry-specification/blame/v1.55.0/specification/common/attribute-type-mapping.md

Fixes include dir of utf8_validity when it's imported as a sub direct…

49895b1

…ory.

Fixes feedbacks

2999fdb

owent force-pushed the validate_utf8_string_in_otlp branch from abd6f54 to 2999fdb Compare April 26, 2026 08:57

owent requested review from ThomsonTan and marcalff April 26, 2026 13:16

Merge branch 'main' into validate_utf8_string_in_otlp

bc87985

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