Wicket Error pages with Spring boot application

[tkruse]

Hi,
we struggle getting our error pages configured using Spring Boot(1.1.4.RELEASE) and wicket 6 with java-based configuration (no web-xml). We use the DispatcherServlet to provide additional REST endpoints

Our filter-chain config looks like this:

 @Bean
    public FilterRegistrationBean wicketFilter() {
        FilterRegistrationBean bean = new FilterRegistrationBean();
        WicketFilter filter = new WicketFilter(ourApplication());
        filter.setFilterPath("");
        bean.setFilter(filter);
        bean.addUrlPatterns("/*");
        return bean;
    }

    @Bean
    public ServletRegistrationBean dispatcherRegistration(DispatcherServlet dispatcherServlet) {
        ServletRegistrationBean registration = new ServletRegistrationBean(dispatcherServlet);
        // since servlets come after filters, wicket gets first chance to handle requests
        registration.addUrlMappings("/*");
        return registration;
    }

What we want are error pages that are served by wicket, e.g. we have a page mounted at /404 that should be used for 404 pages. However we currently only get the "Whitelabel Error Page" provided by Spring boot, saying: "This application has no explicit mapping for /error, so you are seeing this as a fallback.".
We tried different approaches, like http://sporcic.org/2014/05/custom-error-pages-with-spring-boot/, but this does not do true browser redirects it seems (our /404 mounted page is not used, instead the dispatcherServlet reports a failure to find a mapping for /404).

When trying to write a custom Controller for "/error", we get this eror which seems to be cause by Spring boot eagerly mounting the whitelabel error page:

Ambiguous mapping found. Cannot map 'basicErrorController' bean method 
public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
to {[/error],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already 'errorController' bean method
public void de.gulp.backend.rest.ErrorController.error() mapped.
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1553)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)

When using the DispatcherServlet only for urls Mappings "/rest/*", the wicket mechanism for providing 404 page still does not work.

Any idea?

[dsyer]

I haven't got much insight into how wicket generates and maps error pages. Your last effort failed because your controller didn't implement ErrorController, so fixing that might be an option. Registering ErrorPages in the container (like in the link you mentioned) ought to work as well though, as long as there actually is a 404 status in the response, and your filter knows how to render the /404 endpoint (I suspect an error in that last step).

[tkruse]

Thanks for The ErrorController pointer. So it seems we can get something hacked like this:

@Controller
public class CustomErrorController implements ErrorController {

    private static final Logger LOGGER = LoggerFactory.getLogger(RestExceptionHandlingController.class);

    @RequestMapping(value = "/error")
    public void error(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.sendRedirect("/404");
    }


    @Override
    public String getErrorPath() {
        return "/error";
    }
}

which we can further improve.

Regarding the other approach, we can invoke http://localhost:8080/404, so that step works fine.

$ curl -IL localhost:8080/404
HTTP/1.1 302 Found
... (looks fine in the browser)

The filter just never seems to be invoked even when registering an Error page like in the link.
Log shows:

11:51:40,747  WARN springframework.web.servlet.PageNotFound:1114 [] - No mapping found for HTTP request with URI [/foo/bar] in DispatcherServlet with name 'dispatcherServlet'
11:51:40,754  WARN springframework.web.servlet.PageNotFound:1114 [] - No mapping found for HTTP request with URI [/404] in DispatcherServlet with name 'dispatcherServlet'

Also in the browser I see no redirect from the original broken url to /404, so it seems to me the filter chain is not traversed again.

[dsyer]

Maybe the filter is opting out on the forward (it might be marking itself as already executed or something)?

[tkruse]

So, I still have not found a satisfactory solution to this. The error controller is clumsy to mount different pages for different error types, with useful error messages.

I set up a small sample project here:
https://github.com/tkruse/wicket-boot
based on the wicket-quickstart template.

It has a spring Application starter, and the following ULRs work:

• http://localhost:8080/home
• http://localhost:8080/404
• http://localhost:8080/rest/foo

But I don't know how to get a redirect to the 404 page for other urls.

I understand this is not a wicket forum, but I am stuck here.

[dsyer]

Since your Filter is going to have to handle the /404 (and other errors I guess if that's your plan of attack), you need to register it with an explicit DispatcherType.ERROR. It isn't registered that way by default so when the 404 comes to the container it omits your Filter from the chain. Example:

        filterRegistration.setDispatcherTypes(EnumSet.allOf(DispatcherType.class));

Plus you need to register error pages (as already mentioned above) in the container. If the container is embedded you do it with a customizer, e.g.

    @Bean
    public EmbeddedServletContainerCustomizer containerCustomizer() {
        return new EmbeddedServletContainerCustomizer() {
            @Override
            public void customize(ConfigurableEmbeddedServletContainer container) {
                container.addErrorPages(new ErrorPage(HttpStatus.NOT_FOUND, "/404"));
            }
        };
    }

and if it's not embedded you need to add a web.xml.

[tkruse]

Thanks for looking into this, I would never have found that solution. I confirm this works (embedded). Will see how to make this run in war, maybe will add a web.xml to my example, if ServletConfiguration does not work. So far we managed to avoid having a web.xml, thanks to spring-boot.