Implement non-utf8 string to bytes in OTLP exporters.

[owent]

Fixes ##3491

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]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.33%. Comparing base (264d972) to head (abd6f54).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3991      +/-   ##
==========================================
+ Coverage   90.32%   90.33%   +0.02%     
==========================================
  Files         230      230              
  Lines        7299     7299              
==========================================
+ Hits         6592     6593       +1     
+ Misses        707      706       -1     

see 1 file with indirect coverage changes

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[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.

[dbarker]

Most of the changes appear to be new formatting only. Can these format only changes be easily reverted?

[dbarker]

Is this separate target and otlp_utf8_validity package still needed?

[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]

Is there any way to opt-out and NOT perform UTF-8 validation on every string ?

My concern is with performance overhead.

Symbol ENABLE_OTLP_UTF8_VALIDITY is defined if the proper protobuf library is found, but this is not something a end user can control with a CMake option like WITH_OTLP_UTF8_VALIDITY.

[marcalff]

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.

[ThomsonTan]

Link to utf8_range::utf8_validity with PRIVATE should be sufficient?

[ThomsonTan]

Consider add a CHANGELOG entry for this feature work.