Diego Pacheco Tech blog

@Configuration allows you to distribute your Spring Beans across several classes and even jars.  However, with great power comes great responsibility. IMHO you should avoid as much as possible ship configurations with @Configuration inside jars. Because it creates binary coupling on Pojos instances and that has a huge blast radius. In IMHO is completely fine to have Config beans inside in your own service however we are considering a shared libs landscape thats a completely different question and IMHO the wrong move. Let's take a look how @Configuration behavior in sense of ordering and with multiple jars being loaded to the same application.

 Java Agents are an interesting capability of the JVM. Agents can either be Static(Load when the java app starts with a special flag) or they can be Dynamic(using the dynamic API from java we can dynamically bind to a specific JVM PID. Agents can be used to run any code before the app starts or even to change the bytecode. The cool thing about agents is the fact that is a runtime thing and we do not need to change the source code of the target app. Agents are similar to Aspects but IMHO much better. Mockito uses mocks in order to test difficult scenarios, pretty much all observability solutions for logs and metrics also have agents. Today I want to share 2 pocs, one using a vanilla java app and doing bytecode manipulation, The second using Spring Boot 2.x and running code forever in a background thread as the app also runs. So Let's get started!