log4j2 queue/topic configuration by spring - database

Question

Are there any way to configure log4j2 to read Appender attributes from for example a spring bean? I am curious especially in JmsAppender to dynamically set it's target destination based on a parameter read from database and not from JNDI context.
BR
Zoltán

Answer 1

Your best chance is to extend the JMSAppender and override the append methods in the logger. A good example is here
This case , the class extends and uses AMQ to post these messages into. You should be able to extend this from the DB and use API's to get a handle to the Queue or Topic and start appending messages into it. This assumes that you have the right client libraries and permissions to connect to the messaging provider (e.g. in WMQ you may need the QM Name , Queue , Host, port) from the DB (in your case). The extended JMS appender can then be used in your LOG4J2 configuration for sending log messages.

Answer 2

It seems that i found a hybrid soution which is very useful, custom JmsAppender combined with spring context:
#Plugin(name = "OwnJmsAppender", category = "Core", elementType = "appender", printObject = true)
public class OwnJmsAppender extends AbstractAppender {
private final Lock lock = new ReentrantLock();
private Session session;
private Connection connection;
private Destination destination;
private MessageProducer producer;
protected OwnJmsAppender(String name, Filter filter, Layout<? extends Serializable> layout, final boolean ignoreExceptions) {
super(name, filter, layout, ignoreExceptions);
init();
}
#Override
public void append(LogEvent le) {
this.lock.lock();
try {
if (connection == null) {
init();
}
byte[] bytes = getLayout().toByteArray(le);
TextMessage message = session.createTextMessage(new String(bytes, Charset.forName("UTF-8")));
producer.send(message);
} catch (JMSException e) {
LOGGER.error(e);
} finally {
this.lock.unlock();
}
}
#Override
public void stop() {
super.stop();
try {
session.close();
connection.close();
} catch (JMSException e) {
LOGGER.error(e);
}
}
/**
* Reading attributes from log4j2.xml configuration by {#link PluginElement}
* annotation. Also initiates the logger.
*
* #param name
* #param layout
* #param filter
* #return
*/
#PluginFactory
public static OwnJmsAppender createAppender(#PluginAttribute("name") String name,
#PluginElement("PatternLayout") Layout<? extends Serializable> layout, #PluginElement("Filter") final Filter filter) {
if (name == null) {
LOGGER.error("No name provided for OwnJmsAppender");
return null;
}
return new OwnJmsAppender(name, filter, getLayout(layout), true);
}
private static Layout<? extends Serializable> getLayout(Layout<? extends Serializable> layout) {
Layout<? extends Serializable> finalLayout = layout;
if (finalLayout == null) {
finalLayout = PatternLayout.createDefaultLayout();
}
return finalLayout;
}
private void init() {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(CommonDbConfig.class);
ParameterStorage parameterStorage = (DatabaseParameterStorage) context.getBean("databaseParameterStorage");
// the parameterStorage springbean reads params from database
String brokerUri = parameterStorage.getStringValue("broker.url");
String queueName = "logQueue";
context.close();
try {
ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory(brokerUri);
connection = connectionFactory.createConnection();
connection.start();
session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
destination = session.createQueue(queueName);
producer = session.createProducer(destination);
producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);
} catch (JMSException e) {
LOGGER.error(e);
}
}
}
And call it from log4j2.xml:
<Configuration>
<Appenders>
<OwnJmsAppender name="jmsQueue">
<PatternLayout pattern="%maxLen{%d{DEFAULT} [%p] - %m %xEx%n}{500}" />
</OwnJmsAppender>
</Appenders>
<Loggers>
<Logger name="com.your.package" level="info" additivity="false">
<AppenderRef ref="jmsQueue" />
</Logger>
</Loggers>
</Configuration>