In today's security landscape, OAuth2 has become a standard for securing APIs, providing a more robust and flexible approach than basic authentication. My journey into this domain began with a critical solution architecture decision: migrating from basic authentication to OAuth2 client credentials for obtaining access tokens. While Spring Security offers strong support for both authentication methods, I encountered a significant challenge. I could not find a declarative approach that seamlessly integrated basic authentication and JWT authentication within the same application.
This gap in functionality motivated me to explore and develop a solution that not only meets the authentication requirements but also supports comprehensive integration testing. This article shares my findings and provides a detailed guide on setting up Keycloak, integrating it with Spring Security and Spring Boot, and utilizing the Spock Framework for repeatable integration tests. By the end of this article, you will clearly understand how to configure and test your authentication mechanisms effectively with Keycloak as an identity provider, ensuring a smooth transition to OAuth2 while maintaining the flexibility to support basic authentication where necessary.