Spring boot application with embedded tomcat, send access logs to syslog

I have a spring boot application, which runs on AWS EC2 instances.

The deployable is just a jar that has tomcat embedded in it.

I am trying to get the application to send its access log to syslog so that I can use AWS CloudWatch to collect logs from different EC2 instances.

I have tried https://logback.qos.ch/access.html, but it does not work with syslog due to this issue: https://jira.qos.ch/browse/LOGBACK-317

Then I tried CommonsRequestLoggingFilter, this does not seem to send its logs to syslog.

I guess trying to send logs to syslog with Spring boot application is not a rare desire.

Is there any comprehensive way to do this?

Solution

I just implemented this in my application. (For Spring boot 1.5.6)

Make sure your tomcat access logging is on, below is the way access logging is enabled in application.yml -

server: 
 tomcat:
  accesslog:
    enabled: true
    pattern: "<APPNAME> %h %l %u %t \"%r\" %s %b %D"
    prefix: "localhost_access_log"
    suffix: .txt
  basedir: /opt/tomcat

The above will output the access logs in your instances.

Now have your logging defined. For example in application.yml file

logging:
  level:
    org.springframework.web: INFO
    com.project.path : DEBUG
  config: <path to your config xxml>/logback-springboot.xml

The above will get your logback config file from the desired location.

Now, in your code, you need to define your own tomcat access config. For example -

@Configuration
public class AccessValveConfig extends WebMvcConfigurerAdapter implements
 EmbeddedServletContainerCustomizer {

 private static XLogger logger = XLoggerFactory
    .getXLogger(AccessValveConfig.class);


 @Override
  public void customize(ConfigurableEmbeddedServletContainer container) {

     if (container instanceof TomcatEmbeddedServletContainerFactory) {

        TomcatEmbeddedServletContainerFactory factory = 
              (TomcatEmbeddedServletContainerFactory) container;
        AbstractAccessLogValve accessLogValve = new ApiAccessLogValve();
        accessLogValve.setPattern("common");
        factory.addContextValves(accessLogValve);
     } else {
     logger.error("WARNING! this customizer does not support your 
             configured container");
    }
 }
}

public class ApiAccessLogValve extends AbstractAccessLogValve {

  private static XLogger logger = XLoggerFactory
    .getXLogger(ApiAccessLogValve.class);

  public ApiAccessLogValve(){
   super();
  }

 @Override
 protected void log(CharArrayWriter message) {
   synchronized (this) {
    logger.info(message.toString());
   }
 }
}

Now make the necessary configs in your logback xml.

<!--This will print app logs in user facility-->
<appender name="SYSLOG" class="ch.qos.logback.classic.net.SyslogAppender">
 <syslogHost><<your host name>></syslogHost>
 <port>514</port>
 <facility>USER</facility>
 <suffixPattern><<your pattern>></suffixPattern>
</appender>
<!-- This will print your access logs in local0 facility-->
<appender name="LOCAL0" class="ch.qos.logback.classic.net.SyslogAppender">
  <syslogHost><<your host name>></syslogHost>
  <port>514</port>
  <facility>LOCAL0</facility>
  <suffixPattern><<pattern>></suffixPattern>
</appender>

<Logger name="package path to ApiAccessLogValve" level="INFO" 
    additivity="false">
   <appender-ref ref="LOCAL0" />
</Logger>

Now you are all set.