从 Spring Boot 1.5.9 升级到 2.2.6 时，HATEOAS 链接中未考虑上下文路径

Question

I have recently upgraded an older application, based on Spring Boot, from version 1.5.9 to 2.2.6.

Unfortunately, after upgrading, the urls generated with HATEOAS are changed. Basically the context-path is missing from the Links now.

Example:

Before: https://domain.test.com/service/api/endpoint
Now:    https://domain.test.com/service/endpoint

Right now I am using the following configs in application properties:

server.servlet.context-path: /api
server.forward-headers-strategy: FRAMEWORK
spring.data.rest.basePath: /api

(With none, the host is totally different(because of the x-forwarded-host. I have also tried with native, but same behavior)

I have also created a ForwardedHeaderFilter bean.

    @Bean
    public ForwardedHeaderFilter forwardedHeaderFilter() {
        return new ForwardedHeaderFilter();
    }

Is there anything I can do to bypass this issue? Am I doing something wrong?

One alternative would be to adjust the api gateway, but this would be really complicated from a business process perspective so I would prefer a more technical approach.

Thank you !

Answer 1

As a temporary solution, until I have time to really take a deeper look, I have created a new Utility class, that takes care of adjusting the path:

public class LinkUtil {
    private LinkUtil() {
    }

    @SneakyThrows
    public static <T> Link linkTo(T methodOn) {
        String rawPath = WebMvcLinkBuilder.linkTo(methodOn).toUri().getRawPath();
        rawPath = StringUtils.remove(rawPath, "/service");
        BasicLinkBuilder basicUri = BasicLinkBuilder.linkToCurrentMapping().slash("/api").slash(rawPath);

        return new Link(basicUri.toString());
    }
}

Where /api is the context-path.

Then I use it like this:

Link whateverLink = LinkUtil.linkTo(methodOn(WhateverClass.class).whateverMethod(null)).withRel("whatever-rel));

Answer 2

@LoolKovski's temporary solution relies on an existing ServletRequest because of #linkToCurrentMapping. Use the following code if you, too, need to eliminate that restriction:

public class LinkUtil {
    private LinkUtil() {
    }

    @SneakyThrows
    public static <T> Link linkTo(T methodOn) {
        var originalLink = WebMvcLinkBuilder.linkTo(methodOn);
        var rawPathWO = StringUtils.remove(originalLink.toUri().getRawPath(), "/service");
        return originalLink.withHref("/api" + rawPathWO);
    }
}

Actually, in my case the links are generated during one of the RestController beans' initialization, so my real code looks like the following code. I don't need to cut-off some other path part before but only need to prepend a configured context path.

@RestController
public class ExampleController implements ServletContextAware {

@Override
public void setServletContext(ServletContext servletContext) {
    final var executor = Executors.newSingleThreadExecutor();
    executor.submit(() -> {
        someRepository.getExamples().forEach((name, thing) -> {
            Link withRel = linkTo(methodOn(ExampleController.class).getElement(null, name, null))
                    .withSelfRel();
            withRel = withRel.withHref(servletContext.getContextPath() + withRel.toUri().getRawPath());
            thing.add(withRel);
        });
        executor.shutdown();
    });
}

@RequestMapping(path = "/{name}/", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public HttpEntity<Example> getElement(ServletWebRequest req, @PathVariable("name") String name, Principal principal) {
    [...]
}