Can't export message field when exporting tracing, is it because message field is a special field?

Question

Rust event macros do not export correctly using the message field

Here's the rust code that I defined the export with

pub fn init_otlp_tracing(endpoint: &str) -> Result<sdktrace::Tracer, TraceError> {
    let tracer = new_pipeline()
        .tracing()
        .with_exporter(
            opentelemetry_otlp::new_exporter()
                .tonic()
                .with_endpoint(endpoint),
        )
        .with_trace_config(
            opentelemetry_sdk::trace::config().with_resource(Resource::new(vec![
                opentelemetry::KeyValue::new(
                    opentelemetry_semantic_conventions::resource::SERVICE_NAME,
                    "example-otlp",
                ),
            ])),
        )
        .install_batch(opentelemetry_sdk::runtime::Tokio)?;

    Ok(tracer)
}

This is my event macro

event!(target: "target", Level::INFO, name = "xxxx", severity = "severity", message="hello");

I have also conducted the following tests

let message = "hello";
event!(target: "target", Level::INFO, name = "xxxx", severity = "severity", message);
event!(target: "target", Level::INFO, name = "xxxx", severity = "severity", message = message);
event!(target: "target", Level::INFO, name = "xxxx", severity = "severity", message = %message);

But nothing has been gleaned from Collector about this. There are only two attributes, name and severity.

Answer 1

Yes, message is a special field.

When you log with a tracing macro that uses println!-style content, it will be stored as a "message" attribute. The following are equivalent:

info!("now shaving {} yaks", 5);
info!(message = format!("now shaving {} yaks", 5));

In your tests though, you aren't using the former syntax and your own message attribute gets passed as-is.

When bridging from a tracing Event to an opentelemetry Event, the tracing-opentelemetry bidge will interpret the "message" tracing attribute as the opentelemetry event name. I don't know what this means for the OLTP collector you are using, but it will likely appear separately from the rest of the attributes.