How to generate a ddl creation script with a modern Spring Boot + Data JPA and Hibernate setup?

Ah, right after I posted this question a section of the spring data docs caught my eye:

73.5 Configure JPA properties In addition all properties in spring.jpa.properties.* are passed through as normal JPA properties (with the prefix stripped) when the local EntityManagerFactory is created.

So, to answer my own question: prefix the javax.persistence properties with spring.jpa.properties:

spring.jpa.properties.javax.persistence.schema-generation.create-source=metadata
spring.jpa.properties.javax.persistence.schema-generation.scripts.action=create
spring.jpa.properties.javax.persistence.schema-generation.scripts.create-target=create.sql

After doing this, the schema file was generated automatically in the project root.

This is yml specific configuration for making spring boot generate ddl creation script in root folder:

spring:
  jpa:
    properties:
      javax:
        persistence:
          schema-generation:
            create-source: metadata
            scripts:
              action: create
              create-target: create.sql