Add consumer_id to identify the consumer

Resolves open-telemetry#1796

CHANGELOG.md

@@ -30,6 +30,8 @@ release.
 
 - Adding alibaba cloud as a cloud provider.
   ([#1831](https://github.com/open-telemetry/opentelemetry-specification/pull/1831))
+- Add `messaging.consumer_id` to differentiate between message consumers.
+  ([#1810](https://github.com/open-telemetry/opentelemetry-specification/pull/1810))
 
 ### Compatibility
 

semantic_conventions/trace/messaging.yaml

@@ -112,6 +112,14 @@ groups:
           [Operation names](#operation-names) section above.
           If the operation is "send", this attribute MUST NOT be set, since the
           operation can be inferred from the span kind in that case.
+      - id: consumer_id
+        type: string
+        brief: >
+          The identifier for the consumer receiving a message. For Kafka, set it to
+          `{messaging.kafka.consumer_group} - {messaging.kafka.client_id}`, if both are present, or only
+          `messaging.kafka.consumer_group`. For brokers, such as RabbitMQ and Artemis, set it to the `client_id`
+          of the client consuming the message.
+        examples: 'mygroup - client-6'
 
   - id: messaging.consumer.synchronous
     prefix: messaging

specification/trace/semantic_conventions/messaging.md

@@ -167,6 +167,7 @@ For message consumers, the following additional attributes may be set:
 | Attribute  | Type | Description  | Examples  | Required |
 |---|---|---|---|---|
 | `messaging.operation` | string | A string identifying the kind of message consumption as defined in the [Operation names](#operation-names) section above. If the operation is "send", this attribute MUST NOT be set, since the operation can be inferred from the span kind in that case. | `receive` | No |
+| `messaging.consumer_id` | string | The identifier for the consumer receiving a message. For Kafka, set it to `{messaging.kafka.consumer_group} - {messaging.kafka.client_id}`, if both are present, or only `messaging.kafka.consumer_group`. For brokers, such as RabbitMQ and Artemis, set it to the `client_id` of the client consuming the message. | `mygroup - client-6` | No |
 
 `messaging.operation` MUST be one of the following: