We now skip infrastructure role beans during the processing of beans that could be subject to inter-module interaction observability. Previously, we could accidentally trigger a dependency cycle if the ModuleTracingBeanPostProcessor triggered the initial creation of AutoConfigurationPackages as that would then trigger the PostProcessor in turn which would try to lookup the ACP bean again to determine whether it should post process that to apply observability.
Altered the bean definition to rather only refer to a ListableBeanFactory and only lookup the ApplicationModulesRuntime and ApplicationModuleListeners when the ApplicationStartedEvent is handled.
Moved the message population for the failure analyzer to the exception to be able to give more actionable feedback and educated users on the cause of the problem.
Adds ArchUnit as an explicit dependency to spring-modulith-runtime. Registers auto-configuration that throws an exception in case ArchUnit is missing from the classpath (as it is likely that it's declared as test scope dependency only) and a corresponding failure analyzer to give guidance on how to solve the problem.
We now use an AsyncTaskExecutor to bootstrap the ApplicationModules instance at startup asynchronously and - at the same time - do not block an explicit application shutdown. This also more idiomatic compared to using an ExecutorService directly.
The configuration classes declaring SpringBootApplicationRuntime and ApplicationModulesRuntime beans now describe them as infrastructure beans so that they do not get reported as eagly initialized as their initialization will be triggered when creating the BeanPostProcessors our observability support is based on.
The configuration of the observability support now consistently refer to ApplicationModulesRuntime directly and to the Tracer instance via a supplier as the latter is only needed during the actual component invocation while the former is already needed to decide whether to decorate the instances in the first place. Simplify the inheritance arrangement underneath ModuleTracingSupport.
The logging adapter for ApplicationModuleInitializers now properly unwraps proxy types so that the log output uses the user classes properly.
Application modules can now declare instances of ApplicationModuleInititalizer to execute code upon an ApplicationStartedEvent.
This is achieved by registering a corresponding ApplicationListener in SpringModulithRuntimeAutoConfiguration to invoke all instances of AMI sorted via the Comparator introduced in GH-102. To make sure that the invocation order follows topological order, the runtime module strongly depends on JGraphT.
Introduce Spring Modulith Actuator module to expose the application module structure as Spring Boot actuator. This required a Spring Modulith Runtime module to be extracted from the Spring Modulith Observability one. The former now contains the auto-configured ApplicationRuntime and ApplicationModulesRuntime bean instances to be able to bootstrap a ApplicationModules asynchronously on application startup. The actuator module then contains a Spring Boot @Endpoint implementation consuming the ApplicationModules to render JSON describing the application module structure.
