opentelemetry-process-context: implement process context publishing (OTEP-4719)

[herin049]

Description

External profilers and observability tools (such as the OpenTelemetry eBPF Profiler) operate outside the instrumented process and have no access to resource attributes configured inside OpenTelemetry SDKs. OTEP-4719 (Process Context Sharing) introduces a standard mechanism for OpenTelemetry SDKs to publish resource attributes for access by out-of-process readers

This PR introduces the opentelemetry-process-context package as a Rust backed Python extension (built with maturin/pyo3) that implements the process outlined in OTEP-4719. It publishes the SDK's resource attributes to
a memory region that any external reader with access to /proc/<pid>/maps and /proc/<pid>/mem can discover.

Python API

The introduced Python API has a very light surface area, consisting of two methods to publish and unpublish the process context.

def publish_context(resource: Resource) -> None: ...
def unpublish_context() -> None: ...

Compatability

The original OTEP explicitly mentions that this functionality is Linux only. However, I have tried to implement this package in such a way that limited testing/development can be performed natively on any Posix compatible system (e.g. MacOS). However, the full functionality of OTEP-4719 is only available on Linux and Windows is explicitly not supported.

Feature	Linux	macOS
Backing region	memfd_create("OTEL_CTX") -> mmap(MAP_PRIVATE)	Anonymous mmap
Reader discoverability	/proc/<pid>/maps shows memfd:OTEL_CTX	Not discoverable (no /proc)
Fork protection	madvise(MADV_DONTFORK)	Skipped
Mapping name	prctl(PR_SET_VMA_ANON_NAME, "OTEL_CTX")	Skipped
Publish timestamp clock	CLOCK_BOOTTIME	CLOCK_MONOTONIC
Production use	Fully supported	Development/testing only

Fixes #5291

Type of change

Please delete options that are not relevant.

• 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

How Has This Been Tested?

uv run tox -e py314-test-opentelemetry-process-context

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

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

[ocelotl]

Key components of this PR are written in Rust, reviewers of this repo may not be experts in this language. I suggest adding comments to all the rust files for ease of understanding:

publish.rs.txt
proto.rs.txt
lib.rs.txt
convert.rs.txt
build.rs.txt

[ocelotl]

I found a few things that may be required in the OTEP but missing here. If so, they are all very small changes to this PR.

A few other things are minor but also worth of considering.

[ocelotl]

Some more automatic review comments ✌️

[herin049]

@ocelotl I've switched from pulling the proto files in the build.rs to creating a bash script in scripts/ which generates the Rust files, so they're included in the sdist. This should no longer require network access for building.

Also, I've combined publish_context/update_context into a single Python function, so the API now just contains publish_context and unpublish_context methods.

[ocelotl]

Looks good!

Just a question

[Copilot]

Pull request overview

This PR adds a new opentelemetry-process-context package to the OpenTelemetry Python monorepo. The package is a Rust-backed (PyO3/maturin) Python extension that publishes the SDK Resource into a discoverable process memory region for out-of-process readers, following the mechanism described in OTEP-4719.

Changes:

• Introduces the opentelemetry-process-context package (Python API + Rust implementation + tests).
• Adds CI coverage (tox envs + GitHub Actions) and release workflow steps to build/upload native wheels and sdist.
• Adds a maintainer script to regenerate the embedded Rust prost code for the process-context protobufs.

Reviewed changes

Copilot reviewed 23 out of 30 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
uv.lock	Adds the new workspace member and editable dependency entry.
tox.ini	Adds test/lint envs for the new package and constrains tests to Linux.
scripts/proto_codegen_process_context.sh	New script to regenerate Rust prost code from upstream protos.
pyproject.toml	Adds the new package to the workspace dependencies/members and tool config.
opentelemetry-process-context/tests/test_process_context.py	Adds lifecycle + cross-process /proc validation tests.
opentelemetry-process-context/tests/init.py	Test package marker.
opentelemetry-process-context/test-requirements.in	Adds test dependency input for uv compilation.
opentelemetry-process-context/test-requirements.txt	Compiled test dependency lock for the package tests.
opentelemetry-process-context/src/opentelemetry/process_context/init.py	Public API re-export of the extension functions.
opentelemetry-process-context/src/opentelemetry/process_context/version.py	Package version constant.
opentelemetry-process-context/src/opentelemetry/process_context/py.typed	Marks the package as typed.
opentelemetry-process-context/src/opentelemetry/process_context/_rs/init.pyi	Type stubs for the Rust extension module.
opentelemetry-process-context/rust/src/lib.rs	PyO3 module entrypoint exposing publish/unpublish.
opentelemetry-process-context/rust/src/context.rs	Core shared-memory publication logic.
opentelemetry-process-context/rust/src/convert.rs	Converts Python Resource attributes into protobuf AnyValue/Resource.
opentelemetry-process-context/rust/src/proto.rs	Rust module wiring for checked-in generated prost code.
opentelemetry-process-context/rust/src/generated/opentelemetry.proto.common.v1.rs	Generated protobuf types used for encoding attributes.
opentelemetry-process-context/rust/src/generated/opentelemetry.proto.resource.v1.rs	Generated protobuf types for Resource.
opentelemetry-process-context/rust/src/generated/opentelemetry.proto.processcontext.v1development.rs	Generated protobuf types for ProcessContext.
opentelemetry-process-context/rust/Cargo.toml	Rust crate configuration for the extension.
opentelemetry-process-context/rust/Cargo.lock	Rust dependency lockfile for reproducible builds.
opentelemetry-process-context/pyproject.toml	Defines the Python package (maturin backend) and build metadata.
opentelemetry-process-context/README.rst	Package README scaffold.
opentelemetry-process-context/LICENSE	Package license file.
.github/workflows/test.yml	Adds Ubuntu test jobs for the new tox envs.
.github/workflows/lint.yml	Adds lint job for the new package.
.github/workflows/release.yml	Adds wheel/sdist build jobs for the native extension and downloads artifacts into dist/.
.github/workflows/generate_workflows.py	Updates workflow generator to respect tox platform constraints.
.codespellrc	Skips Rust target artifacts and ignores “crate”.
.changelog/5337.added	Adds changelog entry for the new feature/package.

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