Instrument fetch (undici) for HTTP client spans

[Jackson Weber (JacksonWeber)]

Summary

Outgoing LLM HTTP calls produced no HTTP client spans. The distro only registered @opentelemetry/instrumentation-http, which patches Node's core http/https modules — but the OpenAI Node SDK used by LangChain (ChatOpenAI / AzureChatOpenAI) issues its requests via the global fetch (undici) on Node 18+, which was never instrumented.

This registers @opentelemetry/instrumentation-undici (enabled by default) so fetch-based HTTP client spans are produced.

Changes

• Add @opentelemetry/instrumentation-undici@^0.29.0 (matches the pinned @opentelemetry/instrumentation@^0.219.0).
• Add undici?: UndiciInstrumentationConfig to InstrumentationOptions; enabled by default.
• Register UndiciInstrumentation in createInstrumentations.
• Add undici to the A365 disabled-by-default instrumentations.
• Guard against self-instrumentation: when the fetch-based A365 exporter is active, a merged undici ignoreRequestHook skips its export origin. (Undici does not honor tracing suppression, so exporter traffic would otherwise be traced as spurious dependency spans on other exporters, e.g. Azure Monitor.)

Tests

• New test/internal/unit/distro/instrumentations.test.ts (10 tests): undici registered by default / disabled on request; ignore-hook filters exporter origins while tracing real fetch; delegates to caller-provided hooks; caller config is cloned not mutated; _resolveA365ExporterOrigins resolution.
• Updated two SDKStats bitmap assertions in main.test.ts (undici bit now auto-included).
• Full unit suite (907) + functional suite (30) pass; build + lint green.
• Verified end-to-end in a sample app: a direct fetch() and a LangChain ChatOpenAI call both emit HTTP client spans (incl. the POST …/chat/completions LLM request); disabling undici reproduces the missing-span behavior.

[Copilot]

Pull request overview

This PR adds Undici (fetch) instrumentation to ensure outgoing HTTP client spans are emitted for fetch-based SDKs (notably the OpenAI Node SDK used by LangChain) on Node 18+ where fetch is backed by Undici and is not covered by the core http/https instrumentation.

Changes:

• Add @opentelemetry/instrumentation-undici and enable it by default via InstrumentationOptions.undici.
• Register UndiciInstrumentation in createInstrumentations, including an optional origin-based ignoreRequestHook to prevent exporter self-instrumentation.
• Add unit tests covering undici registration/config behavior and A365 exporter-origin resolution; update SDKStats bitmap assertions accordingly.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/internal/unit/main.test.ts	Updates SDKStats instrumentation bitmap assertions to include UNDICI and adds coverage for disabling undici via options.
test/internal/unit/distro/instrumentations.test.ts	New unit tests validating undici instrumentation registration/config and A365 exporter-origin resolution logic.
src/types.ts	Adds undici?: UndiciInstrumentationConfig to the public instrumentation options type with explanatory docs.
src/shared/config.ts	Enables undici instrumentation by default in internal defaults and updates the documented list of supported instrumentations.
src/distro/instrumentations.ts	Registers UndiciInstrumentation and composes an ignoreRequestHook when exporter origins should be filtered.
src/distro/distro.ts	Adds undici to A365 “disabled by default” list and resolves exporter origins to avoid tracing exporter traffic via undici.
package.json	Adds @opentelemetry/instrumentation-undici dependency.
package-lock.json	Adds lock entries for @opentelemetry/instrumentation-undici.
CHANGELOG.md	Documents the new fetch/undici instrumentation feature under Unreleased.

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[Radhika Gupta (rads-1996)]

A little confused here, why do we need to do this? I think A365 drops the http spans anyways.

[Radhika Gupta (rads-1996)]

Do you mind sharing a screenshot of the spans?

[Jackson Weber (JacksonWeber)]

Superseded by #191, which includes this PR's exact commit (a3d5558, the undici/fetch HTTP client span instrumentation) as its first commit, plus the LangChain init-race fix, GenAI span-kind corrections, and wrapRunExecution client-span nesting. Closing in favor of #191.