Use default collection name is missing

Signed-off-by: michaldo <[email protected]>

Author: michaldo

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/observability/DefaultMongoHandlerObservationConvention.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.mongodb.observability;
 
+import io.micrometer.common.KeyValue;
 import io.micrometer.common.KeyValues;
 
 import org.springframework.data.mongodb.observability.MongoObservation.LowCardinalityCommandKeyNames;
@@ -63,6 +64,8 @@ public KeyValues getLowCardinalityKeyValues(MongoHandlerContext context) {
 		if (!ObjectUtils.isEmpty(context.getCollectionName())) {
 			keyValues = keyValues
 					.and(LowCardinalityCommandKeyNames.MONGODB_COLLECTION.withValue(context.getCollectionName()));
+		} else {
+			keyValues = keyValues.and(LowCardinalityCommandKeyNames.MONGODB_COLLECTION.withValue(KeyValue.NONE_VALUE));
 		}
 
 		if(context.getCommandStartedEvent() == null) {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/observability/MongoObservationCommandListener.java

@@ -105,10 +105,6 @@ public void commandStarted(CommandStartedEvent event) {
 			return; // don't instrument commands like "endSessions"
 		}
 
-		if ("hello".equals(event.getCommandName())) {
-			return; // don't instrument healthcheck
-		}
-
 		RequestContext requestContext = event.getRequestContext();
 
 		if (requestContext == null) {

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/observability/MongoObservationCommandListenerTests.java

@@ -20,6 +20,7 @@
 
 import io.micrometer.common.KeyValues;
 import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Tags;
 import io.micrometer.core.instrument.observation.DefaultMeterObservationHandler;
 import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
 import io.micrometer.observation.Observation;
@@ -99,13 +100,17 @@ void commandStartedShouldNotInstrumentWhenNoParentSampleInRequestContext() {
 	}
 
 	@Test
-	void commandStartedShouldNotInstrumentWhenHello() {
+	void commandStartedShouldIncludeCollectionIfMissing() {
 
 		// when
 		listener.commandStarted(new CommandStartedEvent(new MapRequestContext(), 0, 0, null, "some name", "hello", null));
 
 		// then
-		assertThat(meterRegistry).hasNoMetrics();
+		// although command 'hello' is collection-less, metric must have tag "db.mongodb.collection"
+		assertThat(meterRegistry).hasMeterWithNameAndTags(
+				"spring.data.mongodb.command.active",
+				Tags.of("db.mongodb.collection", "none"));
+
 	}
 
 	@Test