Add online and offline sessions metrics

README.md

@@ -333,6 +333,25 @@ This counter counts the number of response errors (responses where the http stat
 keycloak_response_errors{code="500",method="GET",} 1
 ```
 
+##### keycloak_online_sessions
+This gauge indicates the number of online sessions.
+
+```c
+# HELP keycloak_online_sessions Total online sessions
+# TYPE keycloak_online_sessions gauge
+keycloak_online_sessions{realm="test",client_id="application1",} 1.0
+```
+
+##### keycloak_offline_sessions
+This gauge indicates the number of offline sessions.
+
+```c
+# HELP keycloak_offline_sessions Total offline sessions
+# TYPE keycloak_offline_sessions gauge
+keycloak_offline_sessions{realm="test",client_id="application1",} 1.0
+```
+
+
 #### Metrics URI
 The URI can be added to the metrics by setting the environment variable ```URI_METRICS_ENABLED``` to `true`. 
 This will output a consolidated realm URI value to the metrics. The realm value is replaced with a generic `{realm}` value

pom.xml

@@ -64,6 +64,17 @@
             <version>1.19.0</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>4.4</version>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>4.11.0</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
     <build>
         <resources>

src/main/java/org/jboss/aerogear/keycloak/metrics/MetricsEventListener.java

@@ -4,23 +4,35 @@
 import org.keycloak.events.Event;
 import org.keycloak.events.EventListenerProvider;
 import org.keycloak.events.admin.AdminEvent;
+import org.keycloak.models.KeycloakSession;
 
 public class MetricsEventListener implements EventListenerProvider {
 
     public final static String ID = "metrics-listener";
 
     private final static Logger logger = Logger.getLogger(MetricsEventListener.class);
 
+    private final KeycloakSession keycloakSession;
+
+    public MetricsEventListener(KeycloakSession keycloakSession) {
+        this.keycloakSession = keycloakSession;
+    }
+
     @Override
     public void onEvent(Event event) {
         logEventDetails(event);
 
         switch (event.getType()) {
             case LOGIN:
                 PrometheusExporter.instance().recordLogin(event);
+                PrometheusExporter.instance().recordSessions(event, keycloakSession);
                 break;
             case CLIENT_LOGIN:
                 PrometheusExporter.instance().recordClientLogin(event);
+                PrometheusExporter.instance().recordSessions(event, keycloakSession);
+                break;
+            case LOGOUT:
+                PrometheusExporter.instance().recordSessions(event, keycloakSession);
                 break;
             case REGISTER:
                 PrometheusExporter.instance().recordRegistration(event);

src/main/java/org/jboss/aerogear/keycloak/metrics/MetricsEventListenerFactory.java

@@ -10,7 +10,7 @@ public class MetricsEventListenerFactory implements EventListenerProviderFactory
 
     @Override
     public EventListenerProvider create(KeycloakSession session) {
-        return new MetricsEventListener();
+        return new MetricsEventListener(session);
     }
 
     @Override

src/main/java/org/jboss/aerogear/keycloak/metrics/PrometheusExporter.java

@@ -2,15 +2,20 @@
 
 import io.prometheus.client.CollectorRegistry;
 import io.prometheus.client.Counter;
+import io.prometheus.client.Gauge;
 import io.prometheus.client.Histogram;
 import io.prometheus.client.exporter.PushGateway;
 import io.prometheus.client.exporter.common.TextFormat;
 import io.prometheus.client.hotspot.DefaultExports;
+import org.apache.commons.collections4.MapUtils;
 import org.jboss.logging.Logger;
 import org.keycloak.events.Event;
 import org.keycloak.events.EventType;
 import org.keycloak.events.admin.AdminEvent;
 import org.keycloak.events.admin.OperationType;
+import org.keycloak.models.ClientModel;
+import org.keycloak.models.KeycloakSession;
+import org.keycloak.models.RealmModel;
 
 import java.io.BufferedWriter;
 import java.io.IOException;
@@ -60,6 +65,8 @@ public final class PrometheusExporter {
     final Counter responseTotal;
     final Counter responseErrors;
     final Histogram requestDuration;
+    final Gauge totalOnlineSessions;
+    final Gauge totalOfflineSessions;
     final PushGateway PUSH_GATEWAY;
 
     private PrometheusExporter() {
@@ -149,6 +156,18 @@ private PrometheusExporter() {
             .labelNames("realm", "provider", "error", "client_id")
             .register();
 
+        totalOnlineSessions = Gauge.build()
+            .name("keycloak_online_sessions")
+            .help("Total online sessions")
+            .labelNames("realm", "provider", "client_id")
+            .register();
+
+        totalOfflineSessions = Gauge.build()
+            .name("keycloak_offline_sessions")
+            .help("Total offline sessions")
+            .labelNames("realm", "provider", "client_id")
+            .register();
+
         final boolean URI_METRICS_ENABLED = Boolean.parseBoolean(System.getenv("URI_METRICS_ENABLED"));
         if (URI_METRICS_ENABLED){
             responseTotal = Counter.build()
@@ -274,6 +293,25 @@ public void recordLogin(final Event event) {
         pushAsync();
     }
 
+    public void recordSessions(final Event event, final KeycloakSession keycloakSession) {
+        final String provider = getIdentityProvider(event);
+        final RealmModel realmModel = keycloakSession.realms().getRealm(event.getRealmId());
+        final ClientModel clientModel = keycloakSession.clients().getClientByClientId(realmModel, event.getClientId());
+
+        if(clientModel != null) {
+            final Map<String, Long> onlineClientSessionStats = keycloakSession.sessions().getActiveClientSessionStats(realmModel, false);
+            final Optional<Long> onlineSessionCount = Optional.ofNullable(MapUtils.emptyIfNull(onlineClientSessionStats).get(clientModel.getId()));
+
+            final Map<String, Long> offlineClientSessionStats = keycloakSession.sessions().getActiveClientSessionStats(realmModel, true);
+            final Optional<Long> offlineSessionCount = Optional.ofNullable(MapUtils.emptyIfNull(offlineClientSessionStats).get(clientModel.getId()));
+
+            totalOnlineSessions.labels(nullToEmpty(event.getRealmId()), provider, nullToEmpty(event.getClientId())).set(onlineSessionCount.orElse(0L));
+            totalOfflineSessions.labels(nullToEmpty(event.getRealmId()), provider, nullToEmpty(event.getClientId())).set(offlineSessionCount.orElse(0L));
+
+            pushAsync();
+        }
+    }
+
     /**
      * Increase the number registered users
      *