Skip lazy initialization of beans that explicitly set the lazy attribute to false

[jhaeyaert]

Hi,

The suspected issue described below is related to the version 2.2.0.M1 of Spring Boot.

It appears that the management endpoints are not reachable when using the new lazy initialization feature with actuator endpoints exposed on another port than the default one.

Steps to reproduce :

• Create a new project from spring initializr with the new Spring Boot 2.2.0.M1 version
• Add Reactive Web and Actuator dependencies
• Set the properties management.server.port=8081 and spring.main.lazy-initialization=true

Hit the endpoint http://localhost:8081/actuator/health and you'll get a connection refused.

Switch off the lazy initialization and the actuator endpoints will be back again.
Note that actuator endpoints are working correctly if I switch on the lazy initialization and do not change the management port.

Is something I didn't understand or is there a little bug in the lazy initialization feature ?

By the way, thank you for this feature that I have been waiting for a long time!

[wilkinsona]

Thanks for trying out the milestone. This sounds like a bug to me. We caught a similar one that switched off DevTools restart just before we released but this one slipped through.

[wilkinsona]

Adding the following bean to your app should work around the problem for now:

@Bean
static BeanFactoryPostProcessor ensureEagerManagementServerInitializationPostProcessor() {
	return (beanFactory) -> {
		String namePrefix = ManagementContextAutoConfiguration.class.getName() + "$";
		for (String definitionName : beanFactory.getBeanDefinitionNames()) {
			if (definitionName.startsWith(namePrefix)) {
				beanFactory.getBeanDefinition(definitionName).setLazyInit(false);
			}
		}
	};
}

This will ensure that the logic that creates the child context for the management server is not lazy and that the server is created and started.

There's a secondary problem here. The beans in the separate management context that's used when the management port does not match the server port are all initialised eagerly. They should be lazy like the main context so that the server is created and listening for requests but, for example, the endpoints are not created until a request is received.

[wilkinsona]

We're going to explore the possibility of looking at the bean's class via the bean definition or the metadata available from the definition and not setting the lazy init flag if, for example, the bean implements SmartInitializingSingleton.

[tkvangorder]

Is it possible to skip any bean definitions that explicitly set their lazy attribute to false? @Lazy(false)

[philwebb]

@tkvangorder That's a really nice idea, but I think we might need a framework change to be able to do it. Currently AbstractBeanDefinition.lazyInit is a boolean so we don't know if the value is false because that's the default, or if it's because setLazyInit has been called.

[jhoeller]

We could turn this into a Boolean field indeed and provide a Boolean getLazyInit() accessor on AbstractBeanDefinition... allowing Boot to check whether the flag has been set at all before trying to override it. If this sounds feasible for your purposes, please create a spring-framework issue for it.