Spring Boot - How to create a standalone authenthication MICROSERVICE? - spring-boot

Question

I wrote my first backend spring boot application.
I also created a seperate frontend application.
I would like to create a standalone basic authentication microservice.
The authentication thechnology is currently not relevant. It can use JWT, OUTH2, OKTA, whatever.
I emphsize the MICROSERVICE, rather than adding classes to an application code.
This is because all that I could find on the web and in several books was adding this authentication part as an embedded code in a whole spring boot application.
I would like to build an authentication seperate microservice, such the my other microservices (currently I have only one SP, but there will be more), will be able to use it in order to authenticate the users.
I hope I explained myself right :)
Could you please give me pointer for the correct implementation, or some updated tutorial which can help me accomplish this task?
UPDATE:
I have found a really great and up to date tutorial:
https://dzone.com/articles/step-by-step-a-simple-spring-boot-microservices-ba
Enjoy!
Thanks!

Answer 1

As you need an authentication service, you could work on validating the token generated by the authentication microservice.
You could:
Return a token from your authentication microservice;
Create a token validation service in your main microservice
The link below shows how to implement the authentication application in a manner that it works like an authentication gateway through JWT:
https://medium.com/#mool.smreeti/microservices-with-spring-boot-authentication-with-jwt-and-spring-security-6e10155d9db0
Alternatively, you could add a 3rd party solution to be linked to Spring Security. For this option, something like the code bellow in application.yml should work:
spring:
security:
oauth2:
client:
registration:
sts:
provider: sts
client-id: ${STS_CLIENT_ID}
client-secret: ${STS_SECRET_ID}
client-authentication-method: post
authorization-grant-type: client_credentials
provider:
sts:
token-uri: ${STS_URL}
In my opinion, both ways are valid. It depends on your context and scope.