Java Logging
Logging with Spring AOP (before/after) - work I did in ONAP - https://wiki.onap.org/display/DW/Logging+Developer+Guide
Logback in spring boot - https://www.baeldung.com/spring-boot-logging, https://www.mkyong.com/logging/log4j-hello-world-example/
Logging With Spring AOP
Prototyped AOP advice - minimal client changes - just an aspect bean and annotations required
import javax.servlet.http.HttpServletRequest;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;
@Service("daoFacade")
public class ApplicationService implements ApplicationServiceLocal {
@Override
public Boolean health(HttpServletRequest servletRequest) {
Boolean health = true;
// TODO: check database
// Log outside the AOP framework - to simulate existing component logs between the ENTRY/EXIT markers
LoggerFactory.getLogger(this.getClass()).info("Running /health");
return health;
}
}
Aspect References
package cloud.obrienlabs.demo.logging;
import javax.servlet.http.HttpServletRequest;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import cloud.obrienlabs.logging.LogAdapter;
import org.slf4j.LoggerFactory;
@Aspect
public class LoggingAspect {
@Before("execution(* cloud.obrienlabs.*.*(..))")
public void logBefore(JoinPoint joinPoint) {
Object[] args = joinPoint.getArgs();
Object servletRequest = args[0];
LogAdapter.HttpServletRequestAdapter requestAdapter =
new LogAdapter.HttpServletRequestAdapter((HttpServletRequest)servletRequest);
final LogAdapter adapter = new LogAdapter(
LoggerFactory.getLogger(joinPoint.getTarget().getClass()));
try {
adapter.entering(requestAdapter);
} finally {
}
}
@After("execution(* cloud.obrienlabs.*.*(..))")
public void logAfter(JoinPoint joinPoint) {
final LogAdapter adapter = new LogAdapter(
LoggerFactory.getLogger(joinPoint.getTarget().getClass()));
adapter.exiting();
}
Logging Results
Use Case: Single REST call - with ENTRY/EXIT Markers around in-method log
The key here is that you get logs for free - the entry/exit lines are generated - the line in the middle is from java application code.
ELK Stack
Log ELK Stack Kubernetes Troubleshooting
As an aside - at the Linux Foundation we had a similar issue where the logging system caused cluster instability - this was way back in K8S 1.7 before we used resource limits properly. In our case the ELK stack - specifically the logstash container would saturate it's particular EC2 due to excessive logging from not just healthcheck logs but other rogue containers like ones configured as a daemonset running all cores processing jobs in parallel (essentially using all the cores on the worker nodes). |
