Spring Data Rest and Cors

Question

I am developing a Spring Boot application with a Rest interface and a dart fronted.

The XMLHttpRequest does execute a OPTIONS request which is handled totally correct. After this, the final GET ("/products") request is issued and fails:

No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:63343' is therefore not allowed access.

After some debugging I have found the following: The AbstractHandlerMapping.corsConfiguration is populated for all Subclasses except RepositoryRestHandlerMapping. In the RepositoryRestHandlerMapping no corsConfiguration is present / set at creation time and so it won't get recognized as cors path / resource.
=> No CORS headers attached
Could that be the problem? How can I set it?

Configuration classes:

@Configuration
public class RestConfiguration extends RepositoryRestMvcConfiguration {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**").allowCredentials(false).allowedOrigins("*").allowedMethods("PUT", "POST", "GET", "OPTIONS", "DELETE").exposedHeaders("Authorization", "Content-Type");
    }

   ...
}

I even tried to set the Cors per annotation:

@CrossOrigin( methods = RequestMethod.GET, allowCredentials = "false")
public interface ProductRepository extends CrudRepository<Product, String> {


}

Raw request headers:

GET /products HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
authorization: Basic dXNlcjpwYXNzd29yZA==
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/43.0.2357.130 Chrome/43.0.2357.130 Safari/537.36
Content-Type: application/json
Accept: */*
Referer: http://localhost:63343/inventory-web/web/index.html
Accept-Encoding: gzip, deflate, sdch
Accept-Language: de-DE,de;q=0.8,en-US;q=0.6,en;q=0.4

Raw response headers:

HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Type: application/hal+json;charset=UTF-8
Transfer-Encoding: chunked
Date: Thu, 30 Jul 2015 15:58:03 GMT

Versions used: Spring Boot 1.3.0.M2 Spring 4.2.0.RC2

What do I miss?

Answer 1

Indeed, before Spring Data REST 2.6 (Ingalls) only HandlerMapping instances created by Spring MVC WebMvcConfigurationSupport and controllers annotated with @CrossOrigin were CORS aware.

But now that DATAREST-573 has been fixed, RepositoryRestConfiguration now exposes a getCorsRegistry() for global setup and @CrossOrigin annotations on repositories are also recognized so this is the recommended approach. See https://stackoverflow.com/a/42403956/1092077 answer for concrete examples.

For people that have to stick to Spring Data REST 2.5 (Hopper) or previous versions, I think the best solution is to use a filter based approach. You could obviously use Tomcat, Jetty or this one, but be aware that Spring Framework 4.2 also provides a CorsFilter that use the same CORS processing logic that @CrossOrigin and addCorsMappings(CorsRegistry registry) approaches. By passing an UrlBasedCorsConfigurationSource instance to the CorsFilter constructor parameter, you could easily get something as powerful as Spring native CORS global support.

If you are using Spring Boot (which supports Filter beans), it could be something like:

@Configuration
public class RestConfiguration {

    @Bean
    public FilterRegistrationBean corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        CorsConfiguration config = new CorsConfiguration().applyPermitDefaultValues();
        source.registerCorsConfiguration("/**", config);
        FilterRegistrationBean bean = new FilterRegistrationBean(new CorsFilter(source));
        bean.setOrder(0);
        return bean;
    }
}