feat(otel): Add spec for converting otel exceptions to sentry errors (#837)

Author: AbhiPrasad

develop-docs/sdk/performance/opentelemetry.mdx

@@ -113,6 +113,8 @@ class SentrySpanProcessor implements SpanProcessor {
       return;
     }
 
+    generateSentryErrorsFromOtelSpan(otelSpan);
+
     if (sentrySpan instanceof Transaction) {
       updateTransactionWithOtelData(sentrySpan, otelSpan);
       finishTransactionWithContextFromOtelData(sentrySpan, otelSpan);
@@ -361,6 +363,38 @@ if (instrumenter === 'otel') {
 
 You are also free to do both, or an alternative method, the only requirement is that we don't double instrument.
 
+### Step 7: Define `generateSentryErrorsFromOtelSpan`
+
+In OpenTelemetry, spans can have [exception events](https://opentelemetry.io/docs/reference/specification/trace/semantic_conventions/exceptions/). These have a stacktrace, message, and type. We want to convert these to Sentry errors and attach them to the trace.
+
+```ts
+function generateSentryErrorsFromOtelSpan(otelSpan) {
+  otelSpan.events.forEach(event => {
+    // Only convert exception events to Sentry errors.
+    if (event.name !=== 'exception') {
+      return;
+    }
+
+    const attributes = event.attributes;
+
+    const message = attributes[SemanticAttributes.EXCEPTION_MESSAGE];
+    const syntheticError = new Error(message);
+    syntheticError.stack = attributes[SemanticAttributes.EXCEPTION_STACKTRACE];
+    syntheticError.name = attributes[SemanticAttributes.EXCEPTION_TYPE];
+
+    Sentry.captureException(syntheticError, {
+      contexts: {
+        trace: {
+          trace_id: otelSpan.spanContext().traceId,
+          span_id: otelSpan.spanContext().spanId,
+          parent_span_id: otelSpan.parentSpanId,
+        },
+      },
+    });
+  });
+}
+```
+
 ## Span Protocol
 
 Below describe the transformations between an OpenTelemetry span and a Sentry Span. Related: [the interface for a Sentry Span](https://develop.sentry.dev/sdk/event-payloads/span/), [the Relay spec for a Sentry Span](https://github.com/getsentry/relay/blob/master/relay-general/src/protocol/span.rs) and the spec for an [OpenTelemetry span](https://github.com/open-telemetry/opentelemetry-proto/blob/724e427879e3d2bae2edc0218fff06e37b9eb46e/opentelemetry/proto/trace/v1/trace.proto#L80-L256).