I have an application consisting in microservices: gateway + discovery services + microservices. Rigth now I'm implementing Spring security to the zuul gateway so after a succesful login it returns a JWT with the grants. So the Gateway acts as an authorization and authentication server. I think this ways the ecosistem is secure because the gatweay wont allow any unauthorized access to the endpoints.
I'm applying this flow because I dont want to indivually config every microservice. This is a single secure entry point.
And now, I've read about Oauth and made an implementation in a demo app but I dont understand correctly if Ouath2 will make easier my app or will add unnecesary complexity. I read that Spring Auth Server is not yet implemented so I think I would need to use Okta or Keycloack.
What would be the advantage of implementing Oauth2 vs Gateway + Basic Auth + JWT?
As additional note: The app consists of different apps with different UI's, I will distinguish with user can access to what product by its group.
Thank you so much for your advice.