Add OTel gRPC protocol

[zyy17]

What type of enhancement is this?

API improvement

What does the enhancement do?

The current GreptimeDB supports ingesting OTel data by HTTP with protocol-encoded data. To make the OTel ingestion more general, we can add the OTel gRPC protocol. Users can use both HTTP and gRPC to ingest OTel data.

Implementation challenges

No response

[shuiyisong]

greptimedb/src/frontend/src/server.rs

Line 162 in c19a56c

.otlp_handler(self.instance.clone(), user_provider)

We have an OTLP handler in the gRPC server, though it might need some updates.