Hi Ingo,
You need to add one additional dependency “spring-boot-starter-jdbc” otherwise the spring.datasource configuration is ignored. (Note this is not related to camunda spring boot but to spring boot itself.)
For more information please check the following paragraph:
https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-sql.html#boot-features-connect-to-production-database
Best regards,
Yana