The goal is to develop an annotation that marks certain functions to execute predefined logic via an Interceptor such as adding a correlationId to the MDC. I also want to place the code in a shared library so it can be used across multiple services.

Create the annotation and the interceptor

A simple annotation:

@InterceptorBinding  
@Target({METHOD, TYPE})  
@Retention(RUNTIME)  
public @interface AddCorrelationId {  
}

Basic interceptor:

@Interceptor  
@Priority(Interceptor.Priority.APPLICATION)  
@AddCorrelationId  
public class AddCorrelationIdInterceptor {  
  
    @AroundInvoke  
    Object intercept(InvocationContext ctx) throws Exception {  
        try {  
            MDC.put(CORRELATION_ID_MDC_KEY, UUID.randomUUID().toString());  
            return ctx.proceed();  
        } finally {  
            MDC.clear();  
        }    }}

The code above is just plain Java and it is sufficient when the code lives within the service. However, if instead the code lives in a shared library in Quarkus, something extra becomes necessary.

Make it discoverable by Quarkus

Add META-INF/beans.xml

<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee"  
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
       xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_1_1.xsd"
       bean-discovery-mode="all">  
</beans>

Add META-INF/quarkus-extension.yaml. This file is used to define a custom Quarkus extension: it provides metadata about the extension so Quarkus tooling and build processes can recognise it.

name: My Quarkus Commons
description: A collection of shared functions
deployment-artifact: com.alros:my-quarkus-commons