Support gRPC in the OTEL sink

[pront]

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Use Cases

Many OpenTelemetry collectors and backends (e.g., Jaeger, Tempo, Grafana Cloud) expect gRPC as the primary transport protocol on port 4317. Users wanting to send data to these systems currently cannot use Vector's OpenTelemetry sink directly.

Attempted Solutions

No response

Proposal

Perhaps we can reuse code from the Vector sink which already supports gRPC. But this is not a must.

References

• https://opentelemetry.io/docs/specs/otlp/ - Official OTLP protocol specification
• https://github.com/open-telemetry/opentelemetry-proto/blob/main/docs/specification.md#otlpgrpc - gRPC transport details
• https://github.com/vectordotdev/vector/blob/master/src/sinks/vector/config.rs - Existing gRPC implementation in Vector that can be referenced
• https://github.com/vectordotdev/vector/tree/master/lib/opentelemetry-proto - Vector already includes OTLP protobuf definitions

Version

No response

[dogukancagatay]

There's a recent PR for the gRPC support. #24972