Instrumentation of Spring Applications

Depending on the circumstances, spring applications can be monitored with different configurations: - Spring interceptors can be used if solely spring endpoints should be monitored. This is described in Java Servlet Container Example - Spring applications without Sprinng Boot can be instrumented as any other Java application. This is described in AspectJ Instrumentation Example - Spring applications with Spring Boot use a different classloader. Therefore, their instrumentation is described here.

Instrumenting Spring Boot Applications

The instrumentation of Spring Boot requires 3 steps:

• Specification of the instrumentation aspects in the aop.xml (equivalent to AspectJ Instrumentation Example)

• Adaption of the configuration: To adapt the configuration, the annotation @EnableLoadTimeWeaving needs to be added to the spring config. Furthermore, it needs to be specified that the InstrumentationLoadTimeWeaver is used. Therefore, an example configuration can look like this:

  @Configuration
  @EnableLoadTimeWeaving
  public class AppConfig implements LoadTimeWeavingConfigurer {
  
      @Override
      public LoadTimeWeaver getLoadTimeWeaver() {
       return new InstrumentationLoadTimeWeaver();
      }
  }
  

• Configuring the CLI call: While regular applications are called using java -javaagent:kieker-$KIEKERVERSION-aspectj.jar, Spring Boot applications should not be instrumented directly, but instead, the things loaded by the Spring Boot classloader should be instrumented. Therefore, spring-instrument-$SPRINGVERSION.jar needs to be added as an agent before the Kieker agent. Furthermore, the default aop configuration should be disabled for multi-classloader environments, using -Dkieker.monitoring.skipDefaultAOPConfiguration=true. Overall, the call will look like

  java -Dkieker.monitoring.skipDefaultAOPConfiguration=true \
  -javaagent:spring-instrument-$SPRINGVERSION.jar \
  -javaagent:lib/kieker-$KIEKERVERSION-aspectj.jar -jar MyJar.jar
  

A full example can be found in https://github.com/kieker-monitoring/kieker/tree/main/examples/monitoring/probe-spring-boot