[DylanRussell]

Truncate bytes and bytearray attribute values to max_value_length in _clean_attribute_value as mandated by the OpenTelemetry Attribute Limits Specification. Mutable bytearray values are also converted to immutable bytes to preserve attribute immutability.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

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

• I am a human and not a bot
• I have run tox -e precommit
• I have run tox -e typecheck
• I have run the relevant tests and linting tox environments

[opentelemetry-pr-dashboard]

Pull request dashboard status

Waiting on maintainers · refreshed 2026-11-02 18:50 UTC

Merge when ready.

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[Copilot]

🟡 Changes recommended

Byte-array attribute cleaning can emit multiple limit warnings for a single record, violating the specification’s requirement of at most one limit diagnostic per record.

1 open issue

• Emit at most one limit warning per record · New

What changed in this PR

This PR extends the API’s attribute cleaner to apply value-length limits to byte arrays and convert mutable bytearray values to immutable bytes.

Changes:

• Truncate byte-array values, including those nested in sequences and mappings.
• Add tests for truncation and immutable conversion.
• Update parameter documentation and add a changelog entry.

File	Description
opentelemetry-api/​tests/​attributes/​test_attributes.py	Adds byte-array truncation, conversion, and nested-value tests.
opentelemetry-api/​src/​opentelemetry/​attributes/​__init__.py	Applies length limits to byte arrays and converts bytearray to bytes.
.changelog/​5855.fixed	Documents the byte-array truncation fix.

_{Review effort: Balanced}