Struggling with CORS Configuration in Spring Boot REST API for Staging Environment
I've been banging my head against this for hours. I'm trying to configure Currently developing an MVP for a startup and I've hit a roadblock with CORS in my Spring Boot REST API. For my staging environment, I need to ensure that my frontend application, hosted on a different origin, can communicate with the backend without issues. I've tried adding a simple CORS configuration using the `@CrossOrigin` annotation on my controller, but it doesn’t seem to apply universally: ```java @RestController @RequestMapping("/api/v1") @CrossOrigin(origins = "http://localhost:3000") // React app running on this port public class MyController { @GetMapping("/data") public ResponseEntity<List<MyData>> getData() { List<MyData> data = dataService.getAllData(); return ResponseEntity.ok(data); } } ``` However, requests from my frontend still get blocked due to CORS policy errors in the console. I also attempted to configure a global CORS mapping by implementing `WebMvcConfigurer`, but it appears not to have any effect either: ```java @Configuration public class WebConfig implements WebMvcConfigurer { @Override public void addCorsMappings(CorsRegistry registry) { registry.addMapping("/api/**").allowedOrigins("http://localhost:3000").allowedMethods("GET", "POST", "PUT", "DELETE"); } } ``` I ensured that my application is running on port 8080 and the frontend on 3000. The browser console shows errors like: - `Access-Control-Allow-Origin` is missing. - Preflight requests fail due to a 403 status. Is there any additional configuration or debugging steps I might be overlooking? Are there specific headers or methods I need to allow in my CORS setup that could resolve these issues? Your insights would be highly appreciated as I’m aiming for a smooth deployment for our stakeholders soon. I'm developing on Ubuntu 20.04 with Java. I'm open to any suggestions. Thanks for any help you can provide!