Persistence-related fixes and improvements

Add a configuration option to use message persistence. The default is to
not use persistence; if set to "true" in-memory persistence will be
used.
Fix the client using the default file persistence for admin messages,
resulting in errors in deployments where temporary files could not be
opened - typically in containers.
Document deployment steps for quarkus-based versions of Keycloak.

Change-Id: I8430b4b9c8aad536a6f53090a1a14aea7fad5546

README.md

@@ -2,6 +2,10 @@
 
 A Keycloak SPI that publishes events to a MQTT broker.
 
+This SPI has been deployed successfully on a containerized Keycloak 15.0.2
+and on a Keycloak 19.0 server on a kubernetes cluster. It should therefore
+work properly on any version of Keycloak above 15.0.2.
+
 # Build
 
 ```
@@ -10,6 +14,8 @@ mvn clean install
 
 # Deploy
 
+## Keycloak on Wildfly
+
 * Copy target/event-listener-mqtt-jar-with-dependencies.jar to {KEYCLOAK_HOME}/standalone/deployments
 * Edit standalone.xml to configure the MQTT service settings. Find the following
   section in the configuration:
@@ -29,11 +35,27 @@ And add below:
             <property name="username" value="mqtt_user"/>
             <property name="password" value="mqtt_password"/>
             <property name="topic" value="my_topic"/>
+            <property name="usePersistence" value="true">
         </properties>
     </provider>
 </spi>
 ```
 Leave username and password out if the service allows anonymous write access.
 If unset, the default message topic is "keycloak/events".
+By default, the SPI won't use persistence. If set to true, messages will be persisted in memory.
 
 * Restart the keycloak server.
+
+## Keycloak on Quarkus
+
+* Copy the jar archive to /opt/keycloak/providers/ in the keycloak container.
+* run keycloak with the following options:
+
+```
+kc.sh start
+  --spi-events-listener-mqtt-server-uri "tcp://your.mqtt.server:port" \
+  --spi-events-listener-mqtt-username mqtt_user \
+  --spi-events-listener-mqtt-password mqtt_password \
+  --spi-events-listener-mqtt-topic my_topic
+  --spi-events-listener-mqtt-user-persistence true
+```

src/main/java/org/softwarefactory/keycloak/providers/events/mqtt/MQTTEventListenerProvider.java

@@ -47,14 +47,16 @@ public class MQTTEventListenerProvider implements EventListenerProvider {
     private String password;
     public static final String publisherId = "keycloak";
     public String TOPIC;
+    public boolean usePersistence;
 
-    public MQTTEventListenerProvider(Set<EventType> excludedEvents, Set<OperationType> excludedAdminOperations, String serverUri, String username, String password, String topic) {
+    public MQTTEventListenerProvider(Set<EventType> excludedEvents, Set<OperationType> excludedAdminOperations, String serverUri, String username, String password, String topic, boolean usePersistence) {
         this.excludedEvents = excludedEvents;
         this.excludedAdminOperations = excludedAdminOperations;
         this.serverUri = serverUri;
         this.username = username;
         this.password = password;
         this.TOPIC = topic;
+        this.usePersistence = usePersistence;
     }
 
     @Override
@@ -65,7 +67,10 @@ public void onEvent(Event event) {
         } else {
             String stringEvent = toString(event);
             try {
-                MemoryPersistence persistence = new MemoryPersistence();
+                MemoryPersistence persistence = null;
+                if (this.usePersistence == true) {
+                    persistence = new MemoryPersistence();
+                }
                 MqttClient client = new MqttClient(this.serverUri ,publisherId, persistence);
                 MqttConnectOptions options = new MqttConnectOptions();
                 options.setAutomaticReconnect(true);
@@ -84,7 +89,7 @@ public void onEvent(Event event) {
                 client.disconnect();
             } catch(Exception e) {
                 // ?
-                System.out.println("UH OH!! " + e.toString());
+                System.out.println("Caught the following error: " + e.toString());
                 e.printStackTrace();
                 return;
             }
@@ -99,7 +104,11 @@ public void onEvent(AdminEvent event, boolean includeRepresentation) {
         } else {
             String stringEvent = toString(event);
             try {
-                MqttClient client = new MqttClient(this.serverUri ,publisherId);
+                MemoryPersistence persistence = null;
+                if (this.usePersistence == true) {
+                    persistence = new MemoryPersistence();
+                }
+                MqttClient client = new MqttClient(this.serverUri ,publisherId, persistence);
                 MqttConnectOptions options = new MqttConnectOptions();
                 options.setAutomaticReconnect(true);
                 options.setCleanSession(true);
@@ -117,7 +126,7 @@ public void onEvent(AdminEvent event, boolean includeRepresentation) {
                 client.disconnect();
             } catch(Exception e) {
                 // ?
-                System.out.println("UH OH!! " + e.toString());
+                System.out.println("Caught the following error: " + e.toString());
                 e.printStackTrace();
                 return;
             }

src/main/java/org/softwarefactory/keycloak/providers/events/mqtt/MQTTEventListenerProviderFactory.java

@@ -40,10 +40,11 @@ public class MQTTEventListenerProviderFactory implements EventListenerProviderFa
     private String username;
     private String password;
     private String topic;
+    private boolean usePersistence;
 
     @Override
     public EventListenerProvider create(KeycloakSession session) {
-        return new MQTTEventListenerProvider(excludedEvents, excludedAdminOperations, serverUri, username, password, topic);
+        return new MQTTEventListenerProvider(excludedEvents, excludedAdminOperations, serverUri, username, password, topic, usePersistence);
     }
 
     @Override
@@ -68,6 +69,7 @@ public void init(Config.Scope config) {
         username = config.get("username", null);
         password = config.get("password", null);
         topic = config.get("topic", "keycloak/events");
+        usePersistence = config.getBoolean("usePersistence", false);
     }
 
     @Override