Intermittent 403 Forbidden Errors on REST API with Spring Security and OAuth2
I'm not sure how to approach I'm following best practices but I need help solving I'm sure I'm missing something obvious here, but I'm working with intermittent `403 Forbidden` errors when calling my Spring Boot REST API endpoints that are secured with Spring Security and OAuth2... The scenario seems to arise under heavy load, and it appears to be related to token validation. When I use a tool like Postman, sometimes the request succeeds, but other times it fails with the forbidden behavior, even though the access token should be valid. Here's a snippet of my Spring Security configuration: ```java @Configuration @EnableWebSecurity public class SecurityConfig extends WebSecurityConfigurerAdapter { @Override protected void configure(HttpSecurity http) throws Exception { http .authorizeRequests() .antMatchers("/api/public/**").permitAll() .anyRequest().authenticated() .and() .oauth2ResourceServer() .jwt(); } } ``` I've also set up my application to use JWT tokens. The JWT decoder is configured like this: ```java @Bean public JwtDecoder jwtDecoder() { return NimbusJwtDecoder.withJwkSetUri("https://my-auth-server/.well-known/jwks.json").build(); } ``` When I log the access token, it appears valid most of the time, but during high concurrency scenarios, I've noticed some requests return the `403` status. I attempted to debug using Spring's `@ControllerAdvice` to catch the exceptions and log the details, but the logs don't provide much insight. Here’s the method I added: ```java @ControllerAdvice public class CustomExceptionHandler { @ExceptionHandler(AccessDeniedException.class) public ResponseEntity<String> handleAccessDenied(AccessDeniedException ex) { // Log the exception details here return ResponseEntity.status(HttpStatus.FORBIDDEN).body("Access Denied: " + ex.getMessage()); } } ``` I’ve tried increasing the timeout settings in my API client, but that didn’t help. The tokens are set to expire after 15 minutes and are refreshed automatically, but I'm not clear if the refresh process is causing issues during peak loads. Has anyone experienced similar issues with Spring Security and OAuth2? What could be causing these intermittent `403 Forbidden` responses, and how can I effectively troubleshoot this question? Has anyone else encountered this? I'm working with Java in a Docker container on Linux. Thanks in advance!