Sending Logback logs to LogStash via RabbitMQ using JSON Encoder (Spring) - spring-boot

Question

I am using Spring Boot (1.5.4). I wish to send (logback) logs from my services to Logstash via RabbitMQ in a JSON format rather than plain text. This will save me from having to set up a filter on the Logstash side so that formatting can be controlled on the application side (using a Logback Encoder).
I am aware of the Spring logback AMQP Appender for RabbitMQ org.springframework.amqp.rabbit.logback.AmqpAppender however this uses a Layout (plain text) rather than formatted JSON. I would like to use the LogStash Encoder net.logstash.logback.encoder.LogstashEncoder. I would like to use the Appender with the Encoder (I want it all :").

Answer 1

I first extended the AMQPAppender to add the Encoder like so:-
package nz.govt.mpi.util;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.logback.AmqpAppender;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.encoder.Encoder;
import lombok.Getter;
import lombok.Setter;
public class AmqpLogbackAppender extends AmqpAppender {
#Getter
#Setter
private Encoder<ILoggingEvent> encoder;
/**
* We remove the default message layout and replace with the JSON {#link Encoder}
*/
#Override
public Message postProcessMessageBeforeSend(Message message, Event event) {
return new Message(this.encoder.encode(event.getEvent()), message.getMessageProperties());
}
#Override
public void start() {
super.start();
encoder.setContext(getContext());
if (!encoder.isStarted()) {
encoder.start();
}
}
#Override
public void stop() {
super.stop();
encoder.stop();
}
}
And then I set up the logback-spring.xml configuration file like so:-
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<springProperty scope="context" name="rabbitMQHost" source="logback.amqp.host" defaultValue="localhost"/>
<springProperty scope="context" name="rabbitMQPort" source="logback.amqp.port" defaultValue="5672"/>
<springProperty scope="context" name="rabbitMQUsername" source="spring.rabbitmq.username" />
<springProperty scope="context" name="rabbitMQPassword" source="spring.rabbitmq.password" />
<springProperty scope="context" name="rabbitMQExchangeName" source="logback.amqp.exchange.name" defaultValue="mpi.tradedev"/>
<springProperty scope="context" name="rabbitMQRoutingKey" source="logback.amqp.routing.key" defaultValue="mpi.tradedev.logging"/>
<springProperty scope="context" name="serviceName" source="spring.application.name" />
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread, %X{X-B3-TraceId:-},%X{X-B3-SpanId:-}] %-5level %logger{36} - %msg%n</pattern>
</encoder>
</appender>
<appender name="AMQP" class="nz.govt.mpi.util.AmqpLogbackAppender">
<!-- layout is required but ignored as using the encoder for the AMQP message body -->
<layout><pattern><![CDATA[ %level ]]></pattern></layout>
<encoder class="net.logstash.logback.encoder.LogstashEncoder">
<customFields>{"serviceName": "${serviceName}"}</customFields>
</encoder>
<!-- RabbitMQ connection -->
<host>${rabbitMQHost}</host>
<port>${rabbitMQPort}</port>
<username>${rabbitMQUsername}</username>
<password>${rabbitMQPassword}</password>
<exchangeName>${rabbitMQExchangeName}</exchangeName>
<routingKeyPattern>${rabbitMQRoutingKey}</routingKeyPattern>
<declareExchange>true</declareExchange>
<exchangeType>topic</exchangeType>
<generateId>true</generateId>
<charset>UTF-8</charset>
<durable>true</durable>
<deliveryMode>PERSISTENT</deliveryMode>
</appender>
<root level="info">
<appender-ref ref="STDOUT" />
<appender-ref ref="AMQP" />
</root>
</configuration>
I lastly added the required properties to the application.properties file like so:-
spring.application.name=my-app
logback.amqp.host=localhost
logback.amqp.port=5672
logback.amqp.exchange.name=ex_logstash
logback.amqp.routing.key=my-app.logging
spring.rabbitmq.username=rquser
spring.rabbitmq.password=rqpass
I also had to set up the necessary user account in RabbitMQ. When the application runs it creates the topic (ex_logstash) but you must create a queue (qu_logstash) that is bound to that topic with the routing key match (my-app.*).
You then create a logstash configuration to match the queue name.
ex_logstash -> qu_logstash
The logstash.json configuration file example:-
input {
rabbitmq {
host => "localhost"
queue => "qu_logstash"
durable => true
exchange => "ex_logstash"
key => "my-app.*"
threads => 10
type => "topic"
prefetch_count => 200
port => 5672
user => "rquser"
password => "rqpass"
}
}
On the application side you will need the required dependencies in your pom.xml. These are the ones I am using that cover the required classes YMMV:-
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-stream-rabbit</artifactId>
</dependency>
<dependency>
<groupId>net.logstash.logback</groupId>
<artifactId>logstash-logback-encoder</artifactId>
<version>4.9</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.3</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>1.2.3</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<scope>provided</scope>
</dependency>