Adding rule file when configuring kie module programmatically in drools

I'm new to Drools and trying to create a Drools based java app. I have decided to create a Kie Module programmatically instead of writing an XML file. In order to do that, I have below configurations

@Configuration
public class KieContainerConfig {

    private static String drlFile = "com/rules/eligibility.drl";

    @Bean
    public StatelessKieSession kieSession() {

        KieServices kieServices = KieServices.Factory.get();
        KieModuleModel kieModuleModel = kieServices.newKieModuleModel();

        KieBaseModel kieBaseModel1 = kieModuleModel.newKieBaseModel("KBase1 ")
                .setDefault(true)
                .setEqualsBehavior(EqualityBehaviorOption.EQUALITY)
                .setEventProcessingMode(EventProcessingOption.STREAM)
                .addPackage(drlFile); // adding drl file


        kieBaseModel1.newKieSessionModel("KSession1")
                .setDefault(true)
                .setType(KieSessionModel.KieSessionType.STATELESS)
                .setClockType(ClockTypeOption.get("realtime"));

        KieFileSystem kfs = kieServices.newKieFileSystem();

        kfs.writeKModuleXML(kieModuleModel.toXML());

        KieBuilder kieBuilder = kieServices.newKieBuilder(kfs).buildAll();
        List<Message> messages = kieBuilder.getResults().getMessages(Message.Level.ERROR);
        if (!messages.isEmpty()) {

            for (Message err : messages) {
                System.err.println(err);
            }
        }

        KieContainer kieContainer = kieServices.newKieContainer(kieServices.getRepository().getDefaultReleaseId());


        return kieContainer.newStatelessKieSession("KSession1");}

but when I run the code, app emit java.lang.RuntimeException: Unexpected globa error. But when I change the code by removing .addPackage(drlFile); and adding kfs.write(ResourceFactory.newClassPathResource(drlFile)); to the KieFileSystem, Code runs and provide the expected results.

Why I cannot mention the package when creating Kie Base Model instead of using Kie File System's write method?

Solution

Per the Javadoc for KieBaseModel, the addPackage method takes a pattern. Most commonly it's used like this:

KieBaseModel model = ...
    .addPackage("*");

But if you have your rules organized into packages, you could add a package into the model like this:

KieBaseModel model = ...
    .addPackage("org.mycompany.rules");

Your alternative, using classpath resources, is how you'd go about adding individual files.

(I recommend using the XML to configure your system. I too have built Spring and Spring-Boot apps with drools, and have never seen the need to over-complicate my life by doing these things manually that Drools does for you from a config file.)