CROS problem with ALB

Hi jjshen,

Please go through the below steps i hope it will helps to resolve your issue.

Configure CORS in Spring Boot:

• Ensure your Spring Boot application includes CORS headers.

@RestController
public class MyController {

    @CrossOrigin(origins = "https://mydns.com")
    @RequestMapping("/course/listAllCourse")
    public ResponseEntity<?> listAllCourses() {
        // Your code here
    }
}

CORS Configuration Class (if needed):

• Add a global CORS configuration if individual controllers are not sufficient.

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOrigins("https://mydns.com")
                .allowedMethods("GET", "POST", "PUT", "DELETE")
                .allowedHeaders("*")
                .allowCredentials(true);
    }
}

Check ALB Listener Rules:

• Ensure the ALB listener is correctly forwarding HTTPS traffic to the Spring Boot backend.
• ALB itself doesn't manage CORS, but ensure SSL/TLS termination is correctly set up.

Validate SSL/TLS:

• Verify that your certificates are correctly imported and configured on both the ALB and the Spring Boot application.

Testing:

• Test the CORS configuration by making an API request from your Vue.js application to ensure the Access-Control-Allow-Origin header is correctly returned.