RabbitMQ Target for popular NLog logging tool

New in vNEXT: The RabbitMQ target is now fully asynchronous! Logging to RabbitMQ no longer blocks your application threads, resulting in improved performance and reliability, especially under high load or when the broker is slow/unavailable.

• Non-blocking logging: your app remains responsive even if RabbitMQ is slow or down.
• Improved throughput and scalability.
• More robust error handling and buffering.

• The target itself is now async; you do not need to wrap it in <targets async="true"> (though you still can for extra safety).
• Buffering and message discarding now happen inside the RabbitMQ target. See maxBuffer for configuration.
• If you previously relied on the sync behavior, review your error handling and shutdown logic.
• No breaking changes to configuration, but you may want to tune maxBuffer and Timeout for your workload.

<targets>
  <target name="RabbitMqTarget"
      xsi:type="RabbitMq"
      useJSON="true"
      layout="${message}" />
</targets>

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

  <extensions>
    <add assembly="Nlog.RabbitMQ.Target" />
  </extensions>

  <targets async="true">
    <target name="RabbitMqTarget"
        xsi:type="RabbitMq"
        useJSON="true"
        layout="${message}" />
  </targets>

  <rules>
    <logger name="*" minlevel="Trace" writeTo="RabbitMqTarget"/>
  </rules>

</nlog>

Remember to mark your NLog.config file to be copied to the output directory!

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

	<extensions>
		<add assembly="Nlog.RabbitMQ.Target" />
	</extensions>

	<targets>
		<!-- these are the defaults (except 'topic' and 'appid'): -->
		<target name="RabbitMq"
				xsi:type="RabbitMq"
				appid="NLog.RabbitMq.DemoApp"
				correlationId=""
				messageType=""
				topic="DemoApp.Logging.${level}"
				username="guest"
				password="guest"
				hostname="localhost"
				exchange="app-logging"
				exchangeType="topic"
				clientProvidedName=""
				port="5672"
				vhost="/"
				maxBuffer="10240"
				heartBeatSeconds="3"
				Timeout="3000"
				layout="${message}"
				messageSource="nlog://${hostname}/${logger}"
				contentType="text/plain"
				UseJSON="false"
				UseSsl="false"
				SslCertPath=""
				SslCertPassphrase=""
				Compression="None"
				DeliveryMode="NonPersistent">
			<field key="threadid" layout="${threadid}" />
			<field key="hostname" layout="${hostname}" />
		</target>
	</targets>

	<rules>
		<logger name="*" minlevel="Trace" writeTo="RabbitMQTarget"/>
	</rules>

</nlog>

Recommendation - async wrapper target

Make the targets tag look like this: <targets async="true"> ... </targets> so that a failure of communication with RabbitMQ doesn't slow the application down. With this configuration an overloaded message broker will have 10000 messages buffered in the logging application before messages start being discarded. A downed message broker will have its messages in the inner target (i.e. RabbitMQ-target), not in the async buffer (as the RabbitMQ-target will not block which is what AsyncWrapperTarget buffers upon).

Note: As of vNEXT, the RabbitMQ target is itself asynchronous. Wrapping in <targets async="true"> is optional and may provide additional buffering, but is no longer required for non-blocking logging.

Because NLog doesn't expose a single method for shutting everything down (but loads automatically by static properties - the loggers' first invocation to the framework) - you need to add this code to the exit of your application!

LogManager.Shutdown();

Make sure you are using the flag useJSON='true' in your configuration, then you download logstash! Place it in a folder, and add a file that you call 'logstash.conf' next to it:

input {
  amqp {
    durable => true
    exchange => "app-logging"
    exclusive => false
    format => "json_event"
    host => "localhost"
    key => "#"
    name => ""
    passive => false
    password => "guest"
    port => 5672
    prefetch_count => 10
    ssl => false
    # tags => ... # array (optional)
    type => "nlog"
    user => "guest"
    verify_ssl => false
    vhost => "/"
  }
}

output {
  # Emit events to stdout for easy debugging of what is going through
  # logstash.
  stdout { }

  # This will use elasticsearch to store your logs.
  # The 'embedded' option will cause logstash to run the elasticsearch
  # server in the same process, so you don't have to worry about
  # how to download, configure, or run elasticsearch!
  elasticsearch { embedded => true }
}

You then start the monolithic logstash: java -jar logstash-1.1.0-monolithic.jar agent -f logstash.conf -- web. Now you can surf to http://127.0.0.1:9292 and search your logs that you're generating