In this scenario, only Eureka discovery client is present in the classpath of the app-demo project, the spring-cloud-starter-consul-discovery artifact is commented out in build.gradle. The Eureka discovery client is enabled (eureka.client.enabled=true). The app starts successfully as expected.
In the eureka project, start the Eurka server :
gradle clean bootRun
In the config-server project, launch the config server that will register itself with the Eureka server :
gradle clean bootRun
In the app-demo project, launch the demo app
gradle clean bootRun