docs(otel-v2): document client metrics and shared cardinality filter

[yassin-berriai]

Relevant issues

Documents the v2 OpenTelemetry metrics work landing in BerriAI/litellm (v2 OTEL now emits the six gen_ai.client.* metrics with the shared attribute cardinality filter).

What changed

Adds a "Metrics" section to the OTel v2 page (docs/observability/opentelemetry_v2.md) covering three things. First, v2 now emits GenAI client metrics when LITELLM_OTEL_INTEGRATION_ENABLE_METRICS=true (default off, so default behavior is unchanged), shipped through the same OTEL_EXPORTER / OTEL_ENDPOINT / OTEL_HEADERS exporter selection that traces already use. Second, the six emitted instruments with their exact names and units, matching v1 one-for-one so a dashboard built for either reads the other. Third, the metric attribute cardinality filter, which v2 reads from the same callback_settings.otel.attributes surface as v1 (mutually exclusive include_list / exclude_list, metrics-only scope, gen_ai.token.type never filtered out).

It also documents the v2-specific behavior confirmed against the implementation. The filter lives under callback_settings.otel without adding otel to callbacks, since that key would turn on the separate v1 integration while v2 stays driven by LITELLM_OTEL_V2. v2 has no per-instance attributes field, so the global block is the only source, and it resolves lazily on the first recorded metric rather than at startup; a bad config surfaces on that first request and edits take effect only after a restart. The filter applies only on the default OTLP path; preset destinations (arize, arize_phoenix, langfuse_otel, ...) emit with the full attribute set, the same as v1. The config-reference row for LITELLM_OTEL_INTEGRATION_ENABLE_METRICS now links to the new section.

Type

📖 Documentation

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Jun 12, 2026 10:50pm