One microservice or two?

Question

RESTful API

Authentication microservice and user microservice. Should they be one service?

Login and password are sent to the authentication service. Next, he must send a post or get request to the user service to determine the correctness of the entered password.

Answer 1

One or two - depends on the factors specific to your situation. But if there are two, then it is more reasonable to store the login and password in the authentication service.

Answer 2

user authentication occurs in user microservices, the issuance of authorization tokens can occur on another microservice.
You can authorize not only users, but also other applications (if the request is, for example, backend - backend).

Answer 3

there is such an approach: to look at how much the entities with which you have to work intersect, and the terminology specific to the work - it seems to me that there is a complete intersection to the point of confusion - so I would do it as one service.