Preserving hostname on HATEOAS Resource with OpenFeign - microservices

Question

I'm trying to add a URI to a resource located in a different microservice using OpenFeign and a ResourceAssembler, while preserving the hostname from the original request.
When making a REST request to a HATEOAS resource in another microservice, the resource.getId() method returns a link where the hostname is the Docker container hash instead of the original hostname used to make the request.
Controller
#RestController
#RequestMapping("/bulletins")
public class BulletinController {
// Autowired dependencies
#GetMapping(produces = MediaTypes.HAL_JSON_VALUE)
public ResponseEntity<PagedResources<BulletinResource>> getBulletins(Pageable pageable) {
Page<Bulletin> bulletins = bulletinRepository.findAll(pageable);
return ResponseEntity.ok(pagedResourceAssembler.toResource(bulletins, bulletinResourceAssembler));
}
}
Assembler
#Component
public class BulletinResourceAssembler extends ResourceAssemblerSupport<Bulletin, BulletinResource> {
private final AdministrationService administrationService;
#Autowired
public BulletinResourceAssembler(AdministrationService administrationService) {
super(BulletinController.class, BulletinResource.class);
this.administrationService = administrationService;
}
#Override
public BulletinResource toResource(Bulletin entity) {
Resource<Site> siteRessource = administrationService.getSiteBySiteCode(entity.getSiteCode());
\\ Set other fields ...
bulletinRessource.add(siteRessource.getId().withRel("site"));
return bulletinRessource;
}
}
Feign Client
#FeignClient(name = "${feign.administration.serviceId}", path = "/api")
public interface AdministrationService {
#GetMapping(value = "/sites/{siteCode}")
Resource<Site> getSiteBySiteCode(#PathVariable("siteCode") String siteCode);
}
Bulletin Resource
#Data
public class BulletinResource extends ResourceSupport {
// fields
}
Expected result
curl http://myhost/api/bulletins
{
"_embedded" : {
"bulletinResources" : [ {
"entityId" : 1,
"_links" : {
"self" : {
"href" : "http://myhost/api/bulletins/1"
},
"site" : {
"href" : "http://myhost/api/sites/000"
}
}
} ]
},
[...]
}
Actual result
curl http://myhost/api/bulletins
{
"_embedded" : {
"bulletinResources" : [ {
"entityId" : 1,
"_links" : {
"self" : {
"href" : "http://myhost/api/bulletins/1"
},
"site" : {
"href" : "http://b4dc1a02586c:8080/api/sites/000"
}
}
} ]
},
[...]
}
Notice the site href is b4dc1a02586c, which is the Docker container id.

Answer 1

The solution was to manually define a RequestInterceptor for the FeignClient and manually add the X-Forwarded-Host header, as well as define a ForwardedHeaderFilter bean in the service the request was made to.
Client Side
public class ForwardHostRequestInterceptor implements RequestInterceptor {
private static final String HOST_HEADER = "Host";
private static final String X_FORWARDED_HOST = "X-Forwarded-Host";
#Override
public void apply(RequestTemplate requestTemplate) {
ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder
.getRequestAttributes();
if (requestAttributes == null) {
return;
}
HttpServletRequest request = requestAttributes.getRequest();
String host = request.getHeader(X_FORWARDED_HOST);
if (host == null) {
host = request.getHeader(HOST_HEADER);
}
requestTemplate.header(X_FORWARDED_HOST, host);
}
}
Producer side
The producer side also required modification as per the discussion on
https://github.com/spring-projects/spring-hateoas/issues/862
which refers to the following documentation
https://docs.spring.io/spring-hateoas/docs/current-SNAPSHOT/reference/html/#server.link-builder.forwarded-headers
which states to add the following bean in order to use forward headers.
#Bean
ForwardedHeaderFilter forwardedHeaderFilter() {
return new ForwardedHeaderFilter();
}