Spring Boot + React + Keycloak after login 返回 No Access-Controll-Allow-Origin header 存在

Question

I am trying to add a frontend to my SpringBoot application. I also have a users provider connected perfectly, because if I did a CURL it works.

The problem begins when connecting react to Keycloak to do a login, it shows the login page, but when the login is OK it returns
Access to XMLHttpRequest at 'http://localhost:18080/auth/realms/Realm/protocol/openid-connect/token' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

It still problem of Keycloak because it is working by CURL, but I could not reach to configure it well.

I add a * in Web Origins of the Client also.

Answer 1

You won't reproduce CORS problem with curl cause it is browser conventions.

Basically, the browser considers a request as a CORS when a client request contains:

headers:
    Origin: 127.0.0.1
    Set-Fetch-Mode: cors

And server response must contain: Access-Control-Allow-Origin: * where * can be changed for specific resources.

See article about CORS and @CrossOrigin annotation inside Spring