Question about sending big error messages via "grpc-status-details-bin"

[Denis Babochenko]

Hello everyone! I couldn't find a solution on google so I'm posting here:

We have a project which uses grpc-web for handling requests to a Java server from a browser client (this decision was driven by usage of Protobuf for api code generation). Therefore, requests and responses are wrapped into HTTP/2. Whenever server throws an exception, I wrap it into a Status (https://github.com/googleapis/googleapis/.../status.proto), where details is an exception wrapped into Any. This is usually a complex exception with multiple links to different entities and so on.

An error in the response is sent not in the body, but in the "grpc-status-details-bin" header, which is why, if the error is a long binary string (>4Kb), total header size gets too large, and I assume that grpc-web cuts the message down, as It says at https://github.com/grpc/grpc/.../PROTOCOL-HTTP2.md:

> Servers may limit the size of Request-Headers, with a default of 8 KiB suggested. Implementations are encouraged to compute total header size like HTTP/2's SETTINGS_MAX_HEADER_LIST_SIZE: the sum of all header fields, for each field the sum of the uncompressed field name and value lengths plus 32, with binary values' lengths being post-Base64.

So, the question is: is there any known workaround for responding with big error messages? I've thought about streaming chunked errors, but the OK response is not streamed in most cases

[Denis Babochenko]

Sorry, I forgot to mention that we route requests to grpc endpoints nginx, which means that Nginx itself probably fails to send response with >4Kb of headers. So a more precise question would be: is it possible to send an error in response body rather than in header?