I am trying to create spring cloud microservices and also need to include eureka server and zuul as spring cloud tools. Now I created one module in my one spring boot project. I registered that service with eureka server. And also I created one spring boot project for adding zuul service discovery and also registered with eureka project.
Eureka Server will let you add as many microservices (modules of spring boot projects like you said).
From Spring Cloud landing page:
As long as Spring Cloud Netflix and Eureka Core are on the classpath any Spring Boot application with @EnableEurekaClient will try to contact a Eureka server on http://localhost:8761 (the default value of eureka.client.serviceUrl.defaultZone):
That means that you can use a single eureka server for multiple microservices which are registered as clients to the eureka server.
So yes, it's a One-To-Many relationship.
You will want at one point to look into multiple Eureka servers used in load balancing, for redundancy purposes, but for now you will be fine.