Add event name and severity considerations to log-based exception events

.chloggen/exception-log-severity.yaml

@@ -0,0 +1,6 @@
+change_type: enhancement
+component: exception
+note: >
+  Improve exception event definition: add guidance on how to set event name and
+  severity.
+issues: [3311]

docs/exceptions/exceptions-logs.md

@@ -4,7 +4,7 @@ linkTitle: Logs
 
 # Semantic conventions for exceptions in logs
 
-**Status**: [Stable][DocumentStatus]
+**Status**: [Stable, except where otherwise specified][DocumentStatus]
 
 This document defines semantic conventions for recording exceptions on
 [logs](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.55.0/specification/logs/api.md#emit-a-logrecord)
@@ -13,7 +13,16 @@ emitted through the [Logger API](https://github.com/open-telemetry/opentelemetry
 <!-- toc -->
 
 - [Recording an exception](#recording-an-exception)
-- [Attributes](#attributes)
+  - [When not to record exceptions](#when-not-to-record-exceptions)
+  - [Event name](#event-name)
+  - [Severity](#severity)
+    - [FATAL severity](#fatal-severity)
+    - [ERROR severity](#error-severity)
+    - [WARN severity](#warn-severity)
+    - [INFO severity](#info-severity)
+    - [DEBUG severity](#debug-severity)
+    - [TRACE severity](#trace-severity)
+  - [Attributes](#attributes)
   - [Stacktrace representation](#stacktrace-representation)
 
 <!-- tocstop -->
@@ -38,20 +47,139 @@ emitted through the [Logger API](https://github.com/open-telemetry/opentelemetry
 
 ## Recording an exception
 
+> [!NOTE]
+> This document describes how exception events should be recorded and when to avoid
+> recording them. Guidance on when to record exceptions is left to specific
+> semantic conventions authors.
+
+OpenTelemetry Semantic Conventions authors SHOULD define exception events according
+to this document.
+This guidance is also recommended for application developers and instrumentations
+not hosted in OpenTelemetry.
+This document does not apply to logging bridges.
+
 Exceptions SHOULD be recorded as attributes on the
 [LogRecord](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.55.0/specification/logs/data-model.md#log-and-event-record-definition) passed to the [Logger](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.55.0/specification/logs/api.md#logger) emit
-operations. Exceptions MAY be recorded on "logs" or "events" depending on the
-context.
+operations.
+
+Exception events emitted by instrumentations that also record spans for the same
+operation MUST be associated with the corresponding span context.
+
+When language implementations support passing exception instances to the
+[Emit a LogRecord](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.55.0/specification/logs/api.md#emit-a-logrecord) API, instrumentations SHOULD provide the exception instance
+rather than manually setting individual exception attributes.
+
+![Development](https://img.shields.io/badge/-development-blue) Instrumentations
+SHOULD record exceptions as events.
+
+### When not to record exceptions
+
+**Status**: [Development][DocumentStatus]
+
+Some libraries, frameworks, or runtimes generate artificial exceptions for
+operations that end with an unsuccessful error code. When possible,
+instrumentations SHOULD NOT record these artificial exceptions.
+
+For example, FastAPI in Python recommends raising [`HTTPException`](https://fastapi.tiangolo.com/tutorial/handling-errors/#use-httpexception)
+instead of returning a response with an unsuccessful status
+code. Similarly, Spring in Java provides [`ResponseStatusException`](https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/server/ResponseStatusException.html).
+
+### Event name
+
+**Status**: [Development][DocumentStatus]
+
+It is RECOMMENDED to provide an [event name](/docs/general/events.md) that
+describes the instrumented operation with a `.exception` suffix.
+
+For example, [`http.client.request.exception`](/docs/http/http-exceptions.md#http-client-request-exception)
+represents exceptions that occur during an HTTP client request.
+
+Instrumentations that are not specific to a particular operation or domain, such as
+global unhandled exception handlers, SHOULD use the `exception` event name.
+
+### Severity
+
+**Status**: [Development][DocumentStatus]
+
+The severity reflects the expected impact of the exception, not just its presence.
+
+[Severity Number](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.55.0/specification/logs/data-model.md#field-severitynumber)
+SHOULD be provided on all exception events and SHOULD be set based on the context
+in which the exception occurs, following the guidance below.
+
+#### FATAL severity
+
+Exceptions that usually result in application shutdown SHOULD be recorded with
+severity `FATAL` (severity number 21).
 
-To encapsulate proper handling of exceptions API authors MAY provide a
-constructor, `RecordException` method/extension, or similar helper mechanism on
-the `LogRecord` class/structure or wherever it makes the most sense depending on
-the language runtime.
+Examples:
 
-## Attributes
+- The application detects an invalid configuration at startup and shuts down.
+- The application encounters an out-of-memory condition.
+
+> [!NOTE]
+> Instrumentation SHOULD do the best effort to record such errors, but
+> OpenTelemetry SDK and exporters might not have a chance to actually export them.
+
+#### ERROR severity
+
+Exceptions that are unhandled by application code and don't result in application
+shutdown SHOULD be recorded with severity `ERROR` (severity number 17).
+
+Semantic conventions that define `SERVER` or `CONSUMER` spans SHOULD also define
+a corresponding exception event and recommend using `ERROR` severity.
+
+Examples:
+
+- A messaging consumer terminates message processing with an exception.
+- An HTTP server framework error handler catches an exception not handled by the
+  application code.
+
+#### WARN severity
+
+Exceptions that are expected to be handled by application code SHOULD be
+reported with severity `WARN` (severity number 13).
+
+Semantic conventions that define `CLIENT` or `PRODUCER` spans SHOULD also define
+a corresponding exception event and recommend using `WARN` severity.
+
+Examples:
+
+- A connection attempt to a remote service times out.
+- Writing data to a file results in an I/O exception.
+- A client library call fails after exhausting retries because the underlying
+  service is unavailable. The client library instrumentation records a single
+  WARN log; logging of individual retry attempts is left to the lower-level
+  instrumentation.
+
+#### INFO severity
+
+Application developers may use `INFO` severity (number 9) to record exceptions.
+
+#### DEBUG severity
+
+Exceptions that don't indicate an actual issue SHOULD be recorded with severity
+`DEBUG` (severity number 5).
+
+For example, an exception indicating that a request was cancelled on the client
+side is thrown on the server and detected by the server instrumentation.
+
+#### TRACE severity
+
+Application developers may use `TRACE` severity (number 1) to record exceptions.
+Semantic conventions authors SHOULD NOT define exception events with `TRACE`
+severity.
+
+### Attributes
 
 The table below indicates which attributes should be added to the
-[LogRecord](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.55.0/specification/logs/data-model.md#log-and-event-record-definition) and their types.
+[LogRecord](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.55.0/specification/logs/data-model.md#log-and-event-record-definition).
+
+![Development](https://img.shields.io/badge/-development-blue) Instrumentations MAY
+provide additional attributes to describe the context in which the exception occurred.
+Instrumentations that also record spans for the same operation MAY provide a
+configuration option to populate exception events with attributes captured on
+the corresponding span.
 
 <!-- semconv log-exception -->
 <!-- NOTE: THIS TEXT IS AUTOGENERATED. DO NOT EDIT BY HAND. -->

docs/general/recording-errors.md

@@ -111,7 +111,7 @@ public boolean createIfNotExists(String resourceId) throws IOException {
     // we do not set span status to error and the "error.type" attribute
     // as the exception is not an error,
     // but we still log and set attributes that capture additional details
-    logger.withEventName("acme.resource.create.error")
+    logger.withEventName("acme.resource.create.exception")
       .withAttribute("acme.resource.create.status", "already_exists")
       .withException(e)
       .debug();
@@ -124,7 +124,7 @@ public boolean createIfNotExists(String resourceId) throws IOException {
   } catch (IOException e) {
     // this exception is expected to be handled by the caller
     // and could be a transient error
-    logger.withEventName("acme.resource.create.error")
+    logger.withEventName("acme.resource.create.exception")
       .withException(e)
       .warn();
 

docs/how-to-write-conventions/README.md

@@ -219,9 +219,15 @@ When not to define spans:
 
 > [!IMPORTANT]
 >
-> It's a common practice to accompany a span definition with a metric that measures
-> the duration of the same operation. For example, the `http.client.request.duration`
-> metric is recorded alongside the corresponding HTTP client span.
+> It's a common practice to accompany a span definition with:
+>
+> - A metric that measures the duration of the same operation.
+> - An event that records exceptions that prevent this operation from completing
+>   successfully.
+>
+> For example, the `http.client.request.duration` metric and
+> `http.client.request.exception` event are recorded alongside the corresponding
+> HTTP client span.
 
 A span definition should describe the [operation it represents](#what-operation-does-this-span-represent),
 the [naming pattern](#naming-pattern), considerations for setting span [status](#status),