How to utilize spring security annotations in conjunction with keycloak?

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Spring Security is a widely used security framework that provides various security features for applications built on the Spring Framework. Keycloak is an open-source identity and access management solution that provides authentication and authorization services for applications. Let's see how to use Spring Security annotations in conjunction with Keycloak.

Step 1: Configure Keycloak

Before we start using annotations provided by Spring Security, we need to configure Keycloak in our project. We can do this by adding Keycloak dependencies to our project and configuring the Keycloak server URL, realm, and client ID in our application.properties or application.yml file. We also need to create a Keycloak client and add the necessary scopes and roles to allow access to our application.

Step 2: Add Spring Security dependencies

Next, we need to add Spring Security dependencies to our project. We can do this by adding the following dependency to our pom.xml file:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>

Step 3: Configure Spring Security

We need to configure Spring Security to use Keycloak as the authentication and authorization provider. We can do this by creating a SecurityConfig class and annotating it with @EnableWebSecurity and @KeycloakConfiguration. In this class, we need to override configure(HttpSecurity http) method to specify the security rules for our application. We can use annotations provided by Spring Security to restrict access to certain endpoints of our application based on roles and scopes.

For example, the following code restricts access to an endpoint called "/api/secure" to users who have the "user" role:

@Configuration
@EnableWebSecurity
@KeycloakConfiguration
public class SecurityConfig extends KeycloakWebSecurityConfigurerAdapter {

    @Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
        KeycloakAuthenticationProvider provider = keycloakAuthenticationProvider();
        provider.setGrantedAuthoritiesMapper(new SimpleAuthorityMapper());
        auth.authenticationProvider(provider);
    }

    @Bean
    public KeycloakSpringBootConfigResolver keycloakConfigResolver() {
        return new KeycloakSpringBootConfigResolver();
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        super.configure(http);
        http.authorizeRequests()
                .antMatchers("/api/secure").hasRole("user")
                .anyRequest().permitAll();
    }
}

Step 4: Use Spring Security annotations

Now that we have configured Spring Security to use Keycloak, we can use annotations provided by Spring Security to restrict access to endpoints based on roles and scopes. We can use @PreAuthorize, @Secured, and @RolesAllowed annotations to achieve this.

For example, the following code allows only users with the "user" role to access a method:

@RestController
@RequestMapping("/api")
public class MyController {

    @GetMapping("/secure")
    @PreAuthorize("hasRole('user')")
    public String secureMethod() {
        return "This is a secure method";
    }
}

Conclusion

In this article, we learned how to use Spring Security annotations in conjunction with Keycloak. We configured Keycloak as the authentication and authorization provider for our application and used Spring Security annotations to restrict access to certain endpoints based on roles and scopes.