Add log attribute limit configuration (open-telemetry#2861)

Fixes open-telemetry#2860 Adds log attribute limit configuration. These new environment variables bring more consistency between spans and logs.
carlosalberto · Jan 27, 2023 · 970a403 · 970a403
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -210,6 +210,9 @@ release.
 
 - Specify handling of invalid numeric environment variables
   ([#2963](https://github.com/open-telemetry/opentelemetry-specification/pull/2963))
+- Add log-specific attribute limit configuration and clarify that general
+  attribute limit configuration also apply to log records.
+  ([#2861](https://github.com/open-telemetry/opentelemetry-specification/pull/2861))
 
 ### Telemetry Schemas
 

diff --git a/specification/common/README.md b/specification/common/README.md
@@ -91,11 +91,11 @@ limits programmatically. Names of the configuration options SHOULD be the same a
 in the list below.
 
 An SDK MAY implement model-specific limits, for example
-`SpanAttributeCountLimit`. If both a general and a model-specific limit are
-implemented, then the SDK MUST first attempt to use the model-specific limit, if
-it isn't set, then the SDK MUST attempt to use the general limit. If neither are
-defined, then the SDK MUST try to use the model-specific limit default value,
-followed by the global limit default value.
+`SpanAttributeCountLimit` or `LogRecordAttributeCountLimit`. If both a general
+and a model-specific limit are implemented, then the SDK MUST first attempt to
+use the model-specific limit, if it isn't set, then the SDK MUST attempt to use
+the general limit. If neither are defined, then the SDK MUST try to use the
+model-specific limit default value, followed by the global limit default value.
 
 #### Configurable Parameters
 

diff --git a/specification/logs/sdk.md b/specification/logs/sdk.md
@@ -14,6 +14,7 @@
 - [Additional LogRecord interfaces](#additional-logrecord-interfaces)
   * [ReadableLogRecord](#readablelogrecord)
   * [ReadWriteLogRecord](#readwritelogrecord)
+- [LogRecord Limits](#logrecord-limits)
 - [LogRecordProcessor](#logrecordprocessor)
   * [LogRecordProcessor operations](#logrecordprocessor-operations)
     + [OnEmit](#onemit)
@@ -127,6 +128,34 @@ information
 that was added to the `LogRecord` (as with
 [ReadableLogRecord](#readablelogrecord)).
 
+## LogRecord Limits
+
+`LogRecord` attributes MUST adhere to the [common rules of attribute limits](../common/README.md#attribute-limits).
+
+If the SDK implements attribute limits it MUST provide a way to change these
+limits, via a configuration to the `LoggerProvider`, by allowing users to
+configure individual limits like in the Java example below.
+
+The options MAY be bundled in a class, which then SHOULD be called
+`LogRecordLimits`.
+
+```java
+public interface LogRecordLimits {
+  public int getAttributeCountLimit();
+
+  public int getAttributeValueLengthLimit();
+}
+```
+
+**Configurable parameters:**
+
+* [all common options applicable to attributes](../common/README.md#configurable-parameters)
+
+There SHOULD be a message printed in the SDK's log to indicate to the user
+that an attribute was discarded due to such a limit.
+To prevent excessive logging, the message should not be printed once per
+`LogRecord` or per discarded attribute.
+
 ## LogRecordProcessor
 
 `LogRecordProcessor` is an interface which allows hooks for `LogRecord`

diff --git a/specification/sdk-environment-variables.md b/specification/sdk-environment-variables.md
@@ -157,6 +157,17 @@ See the SDK [Span Limits](trace/sdk.md#span-limits) section for the definition o
 | OTEL_EVENT_ATTRIBUTE_COUNT_LIMIT       | Maximum allowed attribute per span event count | 128     |       |
 | OTEL_LINK_ATTRIBUTE_COUNT_LIMIT        | Maximum allowed attribute per span link count  | 128     |       |
 
+## LogRecord Limits
+
+**Status**: [Experimental](document-status.md)
+
+See the SDK [LogRecord Limits](logs/sdk.md#logrecord-limits) section for the definition of the limits.
+
+| Name                                        | Description                                | Default  | Notes |
+| ------------------------------------------- | -------------------------------------------| -------- | ----- |
+| OTEL_LOGRECORD_ATTRIBUTE_VALUE_LENGTH_LIMIT | Maximum allowed attribute value size       | no limit |       |
+| OTEL_LOGRECORD_ATTRIBUTE_COUNT_LIMIT        | Maximum allowed log record attribute count | 128      |       |
+
 ## OTLP Exporter
 
 See [OpenTelemetry Protocol Exporter Configuration Options](./protocol/exporter.md).