I'm planning to run our own Spring Initializr instance. Is there a way to have a set of application properties get written (to application.yml) when a certain option is chosen, ideally in a separate section for each of a set of predefined profiles? I've looked into customising the project-generation process in Initializr and at creating a custom starter. I've come across auto-configuration for starters, but that seems to be about what configuration to default to when this has not been provided by properties, whereas I am after generating the properties. I've also come across an example of a custom Spring Initializr instance generating files, but I need it to modify application.yml without clobbering any other modifications that may have been made to it.
Spring Initializr (the library behind start.spring.io) does not have yaml support and does not allow you to write such file automatically when the project is generated.
It's easy enough for you to add that feature though. The way it works is through a model that contributors would tune + a writer that transform the model into the target output. An analogy of this would be MavenBuild and MavenBuildWriter that generates Maven's pom.xml.
Auto-configuration is indeed completely unrelated to code/configuration generation so no need to look there.