Count users in keycloak_count_users metric

README.md

@@ -195,6 +195,15 @@ This counter counts the number of response errors (responses where the http stat
 keycloak_response_errors{code="500",method="GET",} 1
 ```
 
+##### keycloak_count_users
+This gauge records the count of users.
+
+```c
+# HELP keycloak_count_users Count users
+# TYPE keycloak_count_users gauge
+keycloak_count_users{realm="test",} 1.0
+```
+
 ## Grafana Dashboard
 
 You can use this dashboard or create yours https://grafana.com/dashboards/10441

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

@@ -4,13 +4,23 @@
 import org.keycloak.events.Event;
 import org.keycloak.events.EventListenerProvider;
 import org.keycloak.events.admin.AdminEvent;
+import org.keycloak.events.admin.ResourceType;
+import org.keycloak.events.admin.OperationType;
+import org.keycloak.models.KeycloakSession;
+import org.keycloak.models.RealmModel;
 
 public class MetricsEventListener implements EventListenerProvider {
 
     public final static String ID = "metrics-listener";
 
     private final static Logger logger = Logger.getLogger(MetricsEventListener.class);
 
+    private KeycloakSession session;
+
+    public MetricsEventListener (KeycloakSession session) {
+        this.session = session;
+    }
+
     @Override
     public void onEvent(Event event) {
         logEventDetails(event);
@@ -21,6 +31,7 @@ public void onEvent(Event event) {
                 break;
             case REGISTER:
                 PrometheusExporter.instance().recordRegistration(event);
+                countUsers(session.realms().getRealm(event.getRealmId()));
                 break;
             case REGISTER_ERROR:
                 PrometheusExporter.instance().recordRegistrationError(event);
@@ -37,9 +48,18 @@ public void onEvent(Event event) {
     public void onEvent(AdminEvent event, boolean includeRepresentation) {
         logAdminEventDetails(event);
 
+        if (event.getResourceType() == ResourceType.USER && ( event.getOperationType() == OperationType.CREATE || event.getOperationType() == OperationType.DELETE)) {
+            countUsers(session.realms().getRealm(event.getRealmId()));
+        }
+
         PrometheusExporter.instance().recordGenericAdminEvent(event);
     }
 
+    private void countUsers(RealmModel realm) {
+        int count = session.users().getUsersCount(realm);
+        PrometheusExporter.instance().recordCountUsers(realm.getId(), count);
+    }
+
     private void logEventDetails(Event event) {
         logger.infof("Received user event of type %s in realm %s",
                 event.getType().name(),

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

@@ -2,6 +2,7 @@
 
 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;
@@ -39,6 +40,7 @@ public final class PrometheusExporter {
     final Counter totalRegistrationsErrors;
     final Counter responseErrors;
     final Histogram requestDuration;
+    final Gauge countUsers;
     final PushGateway PUSH_GATEWAY;
 
     private PrometheusExporter() {
@@ -91,6 +93,12 @@ private PrometheusExporter() {
             .labelNames("method")
             .register();
 
+        countUsers = Gauge.build()
+            .name("keycloak_count_users")
+            .help("Count users")
+            .labelNames("realm")
+            .register();
+
         // Counters for all user events
         for (EventType type : EventType.values()) {
             if (type.equals(EventType.LOGIN) || type.equals(EventType.LOGIN_ERROR) || type.equals(EventType.REGISTER)) {
@@ -250,6 +258,17 @@ private String getIdentityProvider(Event event) {
         return identityProvider;
     }
 
+    /**
+     * Set count of users 
+     *
+     * @param realmId The realm
+     * @param count Count users 
+     */
+    public void recordCountUsers(final String realmId, int count) {        
+        countUsers.labels(nullToEmpty(realmId)).set(count);
+        pushAsync();
+    }
+
     /**
      * Write the Prometheus formatted values of all counters and
      * gauges to the stream

src/test/java/org/jboss/aerogear/keycloak/metrics/PrometheusExporterTest.java

@@ -177,6 +177,12 @@ public void shouldCorrectlyRecordResponseErrors() throws IOException {
         assertGenericMetric("keycloak_response_errors", 1, tuple("code", "500"), tuple("method", "POST"));
     }
 
+    @Test
+    public void shouldCorrectlyRecordCountUsers() throws IOException {
+        PrometheusExporter.instance().recordCountUsers(DEFAULT_REALM, 5);
+        assertGenericMetric("keycloak_count_users", 5, tuple("realm", DEFAULT_REALM));
+    }
+
     @Test
     public void shouldTolerateNullLabels() throws IOException {
         final Event nullEvent = new Event();