Customise WebServer to programmatically generate KeyConfig for Helidon MP

Question

I am trying to write a CDI extension which can customise WebServer object to programmatically generate KeyConfig. But the extension is not getting executed in the order I expect.

I wrote a extension class like below

public final class CustomWebServerExtension implements Extension {
    public CustomWebServerExtension() {}
    private void onStartup(@Observes @Priority(11) @Initialized(ApplicationScoped.class) Object event,
                   BeanManager beanManager) {
        ServerCdiExtension server = beanManager.getExtension(ServerCdiExtension.class);
        server.serverBuilder().port(9000).build();
    }
}

I am referring to https://github.com/helidon-io/helidon/issues/3727#issuecomment-993535342 to write this bean class.

When I try to run my server, I see that server.serverBuilder() is null. It seems ServerCdiExtension.startServer is getting executed before code is executed. Any pointers how I can fix this?

Answer 1

This was answered in comments, I will add a summary here.

1. When writing an extension, it must be visible to ServiceLoader (either by creating a file META-INF/services/jakarta.enterprise.inject.spi.Extension with the implementation class a line in the file, or by using module system and adding provides Extension with CustomWebServerExtension)
2. Make sure the imports are from the correct packages:

import jakarta.annotation.Priority;
import jakarta.enterprise.context.ApplicationScoped;
import jakarta.enterprise.context.Initialized;
import jakarta.enterprise.event.Observes;
import jakarta.enterprise.inject.spi.BeanManager;
import jakarta.enterprise.inject.spi.Extension;