Just to quote Boot Docs:
You can set
spring.data.mongodb.uriproperty to change the url, or alternatively specify ahost/port. For example, you might declare the following in yourapplication.properties:
spring.data.mongodb.host=mongoserver
spring.data.mongodb.port=27017
All available options for spring.data.mongodb prefix are fields of MongoProperties:
private String host;
private int port = DBPort.PORT;
private String uri = "mongodb://localhost/test";
private String database;
private String gridFsDatabase;
private String username;
private char[] password;