I'm trying to deploy a Spring Boot application that does not do any servlets in a Weblogic 12c server. Normally the main application class would implement WebApplicationInitializer and then Weblogic would take it from there. When I don't do this for my application, Weblogic installs the war file just fine, but then nothing happens.
Is there some other kind of interface my main application class needs to implement in order for Weblogic to start it up?
You can't deploy an artifact which doesn't implement one of the Weblogic/Java EE deployment standards.
According to the documentation Weblogic supports the following deployment units:
Web Application
Enterprise JavaBean
Resource Adapter
Web Service
Java EE Library
Optional Package
JDBC, JMS, and WLDF Modules
Client Application Archive
Which means that you can deploy an artifact if and only if it implements one of above standards.
Spring Boot application implements neither of those. But implementing WebApplicationInitializer makes the Spring Boot application implement Web Application standard so that it can be deployed to a Servlet Container or any other server that supports Servlet standard.
If you don't want to deploy your application as Web Application you have to manually implement one of the listed standards.