Metrics changed from SmallRye to Micrometer

keycloak/keycloak#15234

release_notes/index.adoc

@@ -13,6 +13,10 @@ include::topics/templates/document-attributes-community.adoc[]
 :release_header_latest_link: {releasenotes_link_latest}
 include::topics/templates/release-header.adoc[]
 
+== {project_name_full} 21.0.0
+include::topics/21_0_0.adoc[leveloffset=2]
+
+
 == {project_name_full} 20.0.0
 include::topics/20_0_0.adoc[leveloffset=2]
 

release_notes/topics/21_0_0.adoc

@@ -0,0 +1,7 @@
+= Keycloak uses Micrometer for metrics
+
+Keycloak provides an optional a metrics endpoint which exports metrics in the Prometheus format.
+In this release the implementation to provide this data switched from SmallRye to Micrometer.
+Due to this change, metrics have been renamed.
+
+See the migration guide for details.

upgrading/topics/keycloak/changes-21_0_0.adoc

@@ -0,0 +1,27 @@
+= Keycloak uses Micrometer for metrics
+
+Keycloak provides an optional a metrics endpoint which exports metrics in the Prometheus format.
+In this release the implementation to provide this data switched from SmallRye to Micrometer, which is the https://quarkus.io/guides/micrometer[recommended metrics library for Quarkus].
+
+Due to this change, metrics have been renamed.
+The following table shows some examples.
+
+Before upgrading it is recommended to review all metrics returned from the endpoint before and after the change, and update their usage in dashboards and alerts.
+
+.Examples of changed metrics names
+|===
+|Old metric name |New metric name
+
+|`base_gc_total`
+|`jvm_gc_pause_seconds_count`
+
+|`base_gc_time_total_seconds`
+|`jvm_gc_pause_seconds_sum`
+
+|`base_thread_count`
+|`jvm_threads_live_threads`
+
+|`vendor_agroal_*`
+|`agroal_*`
+
+|===

upgrading/topics/keycloak/changes.adoc

@@ -1,5 +1,9 @@
 == Migration Changes
 
+=== Migrating to 21.0.0
+
+include::changes-21_0_0.adoc[leveloffset=3]
+
 === Migrating to 20.0.0
 
 include::changes-20_0_0.adoc[leveloffset=3]