Spring (Test)RestTemplate with subdomain throws UnknownHostException

Question

I want to create a test with a subdomain call, but it is not working, I'm getting this exception:

org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://test.localhost:4081/test": test.localhost; nested exception is java.net.UnknownHostException: test.localhost
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:744)
...
Caused by: java.net.UnknownHostException: test.localhost
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
...

Calling only localhost without subdomain works and calling localhost with subdomain using external tool (rest api tester) is also working. I tried to use IPv4 stack (-Djava.net.preferIPv4Stack=true), but I got the same exception. Do I need to set something to get it working? The test looks like this (the code is simplified):

@RunWith(SpringRunner.class)
@SpringBootTest(classes = {...}, webEnvironment=SpringBootTest.WebEnvironment.RANDOM_PORT)
@ActiveProfiles("test")
public class SubdomainTest {

    @Autowired
    private RestTemplateBuilder restTemplateBuilder;

    private int localPort;

    @Override
    public void onApplicationEvent(final ServletWebServerInitializedEvent event) {
        localPort = event.getWebServer().getPort();
    }

    @Test
    public void subdomainTest() throws Exception {
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        converter.setSupportedMediaTypes(
                Arrays.asList(new MediaType[]{MediaType.APPLICATION_JSON, MediaType.APPLICATION_OCTET_STREAM}));
        TestRestTemplate restTemplate = new TestRestTemplate(
                restTemplateBuilder.rootUri("http://test.localhost:"+localPort).additionalMessageConverters(converter)
                , "test"
                , "test");
        ResponseEntity<String> response = restTemplate.getForEntity("/test", String.class); // throws exception
    }

}

score 0 · Answer 1 · answered Nov 03 '20 at 14:24

0

I found a partial solution - add it to hosts file (Windows)

127.0.0.1   test.localhost

But this makes the test setup more complicated for my colleagues... It would be great to have it OS independent.

answered Nov 03 '20 at 14:24

Michal

614
8
20

You can only call a subdomain that actually exists, otherwise you will just have to use localhost in your code instead of test.localhost – Mark Rotteveel Nov 04 '20 at 14:32
I'm just curious, because browsers and http testing tools are able to deal with local subdomains without any change in hosts file. – Michal Nov 05 '20 at 17:10
That would indicate that those tools do their own fallback logic by (recursively?) stripping of the subdomains and trying again. Java only does a lookup of the domain provided, and if neither the hosts file or the DNS returns an IP address, it will fail. – Mark Rotteveel Nov 05 '20 at 19:06

Spring (Test)RestTemplate with subdomain throws UnknownHostException

1 Answers1