[Service Representation] Document precedence order of peer attributes (…

…#26520) * document precedence order of peer attributes * Apply suggestions from code review Co-authored-by: Esther Kim <[email protected]> --------- Co-authored-by: Esther Kim <[email protected]>
DataDog · Nov 27, 2024 · 9e93684 · 9e93684
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diff --git a/content/en/tracing/services/inferred_services.md b/content/en/tracing/services/inferred_services.md
@@ -137,6 +137,20 @@ Peer Tag | Source Attributes
 
 **Note**: Peer attribute values that match IP address formats (for example, 127.0.0.1) are modified and redacted with `blocked-ip-address` to prevent unnecessary noise and tagging metrics with high-cardinality dimensions. As a result, you may encounter some `blocked-ip-address` services appearing as downstream dependencies of your instrumented services.
 
+#### Precedence of peer tags
+
+To assign the name to inferred entities, Datadog uses a specific order of precedence between peer tags, when entities are defined by a combination of multiple tags. 
+
+Entity type | Order of precedence
+-----------|----------------
+Database | `peer.db.name` > `peer.aws.s3.bucket` (For AWS S3) / `peer.aws.dynamodb.table` (For AWS DynamoDB) / `peer.cassandra.contact.points` (For Cassandra) / `peer.couchbase.seed.nodes` (For Couchbase) > `peer.hostname` > `peer.db.system`
+Queue | `peer.messaging.destination` > `peer.kafka.bootstrap.servers` (for Kafka) / `peer.aws.sqs.queue` (for AWS SQS) / `peer.aws.kinesis.stream` (For AWS Kinesis) > `peer.messaging.system`
+Inferred service | `peer.service` > `peer.rpc.service` > `peer.hostname`
+
+If the highest priority tag, such as `peer.db.name`, is not captured as part of the instrumentation, Datadog uses the second highest priority tag, like `peer.hostname`, and continue in that order.
+
+**Note**: Datadog never sets the `peer.service` for inferred databases and queues. `peer.service` is the highest priority peer attribute. If set, it take precedence over all other attributes.
+
 ## Migrate to global default service naming
 
 With inferred services, service dependencies are automatically detected from existing span attributes. As a result, changing service names (using the `service` tag) is not required to identify these dependencies.