Deploy Spring-based web app in Undertow - spring

Question

I am trying to migrate our Spring-based web app from Tomcat 8 to Undertow.
We use Spring's WebApplicationInitializer for the programmatic configuration of Spring-MVC and HibernateTransactionManager.
There is a ServletContainerInitializerInfo class (Javadoc) that seems to serve my purpose, e.g I can instantiate it and then follow the steps given in Undertow docs (link) to start the server:
ServletContainerInitializerInfo sciInfo =
new ServletContainerInitializerInfo(containerInitializerClass,
instanceFactory, handlesTypes);
DeploymentInfo servletBuilder = Servlets.deployment()
.addServletContainerInitalizer(sciInfo);
DeploymentManager manager = Servlets.defaultContainer()
.addDeployment(servletBuilder);
manager.deploy();
PathHandler path = Handlers.path(Handlers.redirect("/myapp"))
.addPrefixPath("/myapp", manager.start());
Undertow server = Undertow.builder()
.addHttpListener(8080, "localhost")
.setHandler(path)
.build();
server.start();
The problem is that I don't know what to substitute for instanceFactory and handlesTypes arguments in call to ServletcontainerInitializerInfo constructor. In addition, the name of the addServletContainerInitalizer method is mis-spelled (should be Initializer instead of Initalizer).
Can someone please help?
Thanks!

Answer 1

Undertow uses InstanceFactory<T> as an extension point for dependency injection or other customization of an instance of a given class after instantiation.
The handlesTypes argument would be the set of all classes corresponding to the #HandlesTypes annotation on your servlet container initializer.
If your initializer has no #HandlesTypes and does not require dependency injection, you can simply try this:
MyInitializer initializer = new MyInitializer();
InstanceFactory<MyInitializer> instanceFactory
= new ImmediateInstanceFactory<>(initializer);
ServletContainerInitializerInfo sciInfo =
new ServletContainerInitializerInfo(MyInitializer.class,
instanceFactory, new HashSet<Class<?>>());