From e110e6cf8dfbcd0c4741a09b99bef5a5a9c07f13 Mon Sep 17 00:00:00 2001
From: Luca Palmieri <lpalmieri@truelayer.com>
Date: Wed, 28 Apr 2021 21:23:53 +0100
Subject: [PATCH] Add error details.

---
 src/root_span_builder.rs | 7 +++++++
 src/root_span_macro.rs   | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/src/root_span_builder.rs b/src/root_span_builder.rs
index da39a3fcd..5b9a39156 100644
--- a/src/root_span_builder.rs
+++ b/src/root_span_builder.rs
@@ -24,6 +24,8 @@ pub trait RootSpanBuilder {
 /// - Request path (`http.target`);
 /// - Status code (`http.status_code`);
 /// - [Request id](crate::RequestId) (`request_id`);
+/// - `Display` (`exception.message`) and `Debug` (`exception.details`) representations of the error, if there was an error;
+/// - [Request id](crate::RequestId) (`request_id`);
 /// - [OpenTelemetry trace identifier](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/overview.md#spancontext) (`trace_id`). Empty if the feature is not enabled;
 /// - OpenTelemetry span kind, set to `server` (`otel.kind`).
 ///
@@ -45,6 +47,11 @@ impl RootSpanBuilder for DefaultRootSpanBuilder {
             }
             Err(error) => {
                 let response_error = error.as_response_error();
+                span.record(
+                    "exception.message",
+                    &tracing::field::display(response_error),
+                );
+                span.record("exception.details", &tracing::field::debug(response_error));
                 let status_code = response_error.status_code();
                 span.record("http.status_code", &status_code.as_u16());
 
diff --git a/src/root_span_macro.rs b/src/root_span_macro.rs
index db6217e50..2b4ee67b0 100644
--- a/src/root_span_macro.rs
+++ b/src/root_span_macro.rs
@@ -90,6 +90,9 @@ macro_rules! root_span {
                 otel.status_code = $crate::root_span_macro::private::tracing::field::Empty,
                 trace_id = $crate::root_span_macro::private::tracing::field::Empty,
                 request_id = %request_id,
+                exception.message = $crate::root_span_macro::private::tracing::field::Empty,
+                // Not proper OpenTelemetry, but their terminology is fairly exception-centric
+                exception.details = $crate::root_span_macro::private::tracing::field::Empty,
                 $($field)*
             );
             std::mem::drop(connection_info);