[BUG]: gRPC metadata becomes span attributes, not a safe default?

[guisehn]

Tracer Version(s)

2.30.0

Ruby Version(s)

Any version

Relevent Library and Version(s)

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Bug Report

Datadog's gRPC client interceptor automatically adds the RPC metadata as span attributes. This happens here:

dd-trace-rb/lib/datadog/tracing/contrib/grpc/datadog_interceptor/client.rb

Line 53 in 716872e

span.set_tags(metadata)

Metadata in gRPC is analogous to HTTP headers. One of the use cases is authentication, e.g. transferring API keys, user authentication data, etc. More info

For this reason, blindly sending metadata fields as span attributes doesn't seem to be a safe default.

Additionally, passing things in metadata seems to be the only way to add custom client span attributes at the moment, but anything in metadata is also transferred through the network to the gRPC server. Could we have a way to pass span attributes without adding them to the metadata?

Reproduction Code

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Configuration Block

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Error Logs

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Operating System

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