try to add jetty 12 session metrics (failing)

Author: SylvainJuge

instrumentation/jmx-metrics/library/src/main/resources/jmx/rules/jetty.yaml

@@ -34,7 +34,7 @@ rules:
         metric: queue.size
         desc: The current job queue size
 
-  # Thread metrics for Jetty 11 and earlier
+  # Thread metrics for Jetty 9 to 11
   - bean: org.eclipse.jetty.util.thread:type=queuedthreadpool,id=*
     prefix: jetty.thread.
     unit: "{thread}"
@@ -79,10 +79,36 @@ rules:
         unit: "{operation}"
         desc: The number of select calls
 
+  # Session metrics for Jetty 12
+  - bean: org.eclipse.jetty.session:context=*,type=defaultsessioncache,id=*
+    # org.eclipse.jetty.session:context=ROOT,type=defaultsessioncache,id=0
+    prefix: jetty.session.
+    unit: "{session}"
+    metricAttribute:
+      # 'context' corresponds to the webapp context path
+      jetty.context: param(context)
+      # 'id' is a "technical ID" with a single '0' value by default
+      jetty.session.cache.id: param(id)
+    mapping:
+      # jetty.session.count
+      sessionsCurrent:
+        metric: count
+        type: updowncounter
+        desc: Current number of active sessions
+      # jetty.session.count.max
+      sessionsMax:
+        metric: count.max
+        # gauge because it can't be aggregated
+        type: gauge
+        desc: Maximum number of active sessions
+
+  # Session metrics for Jetty 9 to 11
   - bean: org.eclipse.jetty.server.session:context=*,type=sessionhandler,id=*
     prefix: jetty.session.
     metricAttribute:
+      # 'context' corresponds to the webapp context path
       jetty.context: param(context)
+      # 'id' is a "technical ID" with a single '0' value by default
       jetty.session.handler.id: param(id)
     mapping:
       # jetty.session.created.count

instrumentation/jmx-metrics/library/src/test/java/io/opentelemetry/instrumentation/jmx/rules/JettyIntegrationTest.java

@@ -11,8 +11,11 @@
 import io.opentelemetry.instrumentation.jmx.rules.assertions.AttributeMatcherGroup;
 import java.time.Duration;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 import org.testcontainers.containers.GenericContainer;
@@ -35,13 +38,13 @@ void testCollectedMetrics(int jettyMajorVersion) {
     jvmArgs.add(javaAgentJvmArgument());
     jvmArgs.addAll(javaPropertiesToJvmArgs(otelConfigProperties(yamlFiles)));
 
-    String jettyModules = "jmx,http,";
+    Set<String> jettyModules = new HashSet<>(Arrays.asList("jmx", "http"));
     if (jettyMajorVersion >= 12) {
-      jettyModules += "statistics";
+      jettyModules.add("statistics");
     } else {
-      jettyModules += "stats";
+      jettyModules.add("stats");
     }
-    String addModulesArg = "--add-to-startd=" + jettyModules;
+    String addModulesArg = "--add-to-startd=" + String.join(",", jettyModules);
 
     GenericContainer<?> container =
         new GenericContainer<>(
@@ -132,7 +135,31 @@ private static MetricsVerifier createMetricsVerifier(int jettyMajorVersion) {
                                 attributeWithAnyValue("jetty.selector.id"),
                                 attributeWithAnyValue("jetty.selector.context"))));
 
-    if (jettyMajorVersion < 12) {
+    if (jettyMajorVersion >= 12) {
+      verifier
+          .add(
+              "jetty.session.count",
+              metric ->
+                  metric
+                      .isUpDownCounter()
+                      .hasDescription("Current number of active sessions")
+                      .hasUnit("{session}")
+                      .hasDataPointsWithAttributes(
+                          attributeGroup(
+                              attributeWithAnyValue("jetty.context"),
+                              attributeWithAnyValue("jetty.session.cache.id"))))
+          .add(
+              "jetty.session.count.max",
+              metric ->
+                  metric
+                      .isUpDownCounter()
+                      .hasDescription("Maximum number of active sessions")
+                      .hasUnit("{session}")
+                      .hasDataPointsWithAttributes(
+                          attributeGroup(
+                              attributeWithAnyValue("jetty.context"),
+                              attributeWithAnyValue("jetty.session.cache.id"))));
+    } else {
       verifier
           .add(
               "jetty.session.created.count",
@@ -179,7 +206,6 @@ private static MetricsVerifier createMetricsVerifier(int jettyMajorVersion) {
                               attributeWithAnyValue("jetty.context"),
                               attributeWithAnyValue("jetty.session.handler.id"))));
     }
-
     return verifier;
   }
 }