AppendCustomErrorHeader sets a CustomErrorMetadataKey gRPC header on the passed in context, using the passed in error data as the header's value.

AppendHeaders parses the provided GRPC headers and attaches them to the provided context.

LogRequests logs the gRPC backend as well as request duration when the log level is set to debug or higher.

LogStream prints the method at DEBUG level at the start of the stream.

CustomErrorMetadataKey is the name of the metadata key storing additional error information.

HttpCodeMetadataKey is the key to use when setting custom HTTP status codes in gRPC metadata.