How to add custom ApplicationContextInitializer to a spring boot application?

One way to add custom ApplicationContextInitializer to spring web application is to add it in the web.xml file as shown below.

<context-param>
    <param-name>contextInitializerClasses</param-name>
    <param-value>somepackage.CustomApplicationContextInitializer</param-value>
</context-param>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

But since I am using spring boot, is there any way I don't have to create web.xml just to add CustomApplicationContextInitializer?

You can register them in META-INF/spring.factories

org.springframework.context.ApplicationContextInitializer=\
com.example.YourInitializer

You can also add them on your SpringApplication before running it

application.addInitializers(YourInitializer.class);
application.run(args);

Or on the builder

new SpringApplicationBuilder(YourApp.class)
    .initializers(YourInitializer.class);
    .run(args);

It wasn't obvious from the doc at first glance so I opened #5091 to check.