如何将自定义 restTemplate 实例添加到 RestTemplateEurekaHttpClient

Question

My intention is to replace Jersey implementation of eureka client with the one provided with a Spring restTemplate.

Then, replace the standard implementation of the rest template with one that trust all certificates (i know it's not raccomanded but it doesn't matter right now) in order to register my service to a secure (https) eureka server.

I'm using Spring boot 2.2.1-RELEASE and Spring cloud Hoxton.RC2.

According to the official documentation in a spring boot project declaring eureka client this way

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>com.sun.jersey</groupId>
                    <artifactId>jersey-client</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.sun.jersey</groupId>
                    <artifactId>jersey-core</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.sun.jersey.contribs</groupId>
                    <artifactId>jersey-apache-client4</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

force the application to use a RestTemplate as the Eureka Client.

I Already have a custom RestTemplate implementation in my application, lets call it RestTemplateImpl , i'll omit implementation code cause it's irrelevant.

When the application start i was expectin my RestTemplateImpl to be injected as the deafault eureka client implementation, but it wasn't.

As the exception says

org.springframework.web.client.ResourceAccessException: I/O error on POST request for "https://localhost:3000/eureka/apps/MY-API": java.security.cert.CertificateException: No name matching localhost found; nested exception is javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: No name matching localhost found
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:751) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:677) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:586) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.cloud.netflix.eureka.http.RestTemplateEurekaHttpClient.register(RestTemplateEurekaHttpClient.java:73) ~[spring-cloud-netflix-eureka-client-2.2.0.RC2.jar:2.2.0.RC2]
    at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$1.execute(EurekaHttpClientDecorator.java:59) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.RedirectingEurekaHttpClient.executeOnNewServer(RedirectingEurekaHttpClient.java:118) ~[eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.RedirectingEurekaHttpClient.execute(RedirectingEurekaHttpClient.java:79) ~[eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.register(EurekaHttpClientDecorator.java:56) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$1.execute(EurekaHttpClientDecorator.java:59) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.RetryableEurekaHttpClient.execute(RetryableEurekaHttpClient.java:120) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.register(EurekaHttpClientDecorator.java:56) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$1.execute(EurekaHttpClientDecorator.java:59) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.SessionedEurekaHttpClient.execute(SessionedEurekaHttpClient.java:77) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.register(EurekaHttpClientDecorator.java:56) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.DiscoveryClient.register(DiscoveryClient.java:847) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.InstanceInfoReplicator.run(InstanceInfoReplicator.java:121) [eureka-client-1.9.13.jar:1.9.13]
    at com.netflix.discovery.InstanceInfoReplicator$1.run(InstanceInfoReplicator.java:101) [eureka-client-1.9.13.jar:1.9.13]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_212]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_212]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_212]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [na:1.8.0_212]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_212]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_212]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_212]

Spring uses a RestTemplateEurekaHttpClient .

Looking into the source code i found no way to inject my RestTemplateImpl in favor of the one existing.

public class RestTemplateTransportClientFactory implements TransportClientFactory {

    @Override
    public EurekaHttpClient newClient(EurekaEndpoint serviceUrl) {
        return new RestTemplateEurekaHttpClient(restTemplate(serviceUrl.getServiceUrl()),
                serviceUrl.getServiceUrl());
    }

    private RestTemplate restTemplate(String serviceUrl) {
        RestTemplate restTemplate = new RestTemplate();
        try {
            URI serviceURI = new URI(serviceUrl);
            if (serviceURI.getUserInfo() != null) {
                String[] credentials = serviceURI.getUserInfo().split(":");
                if (credentials.length == 2) {
                    restTemplate.getInterceptors().add(new BasicAuthorizationInterceptor(
                            credentials[0], credentials[1]));
                }
            }
        }
        catch (URISyntaxException ignore) {

        }

        restTemplate.getMessageConverters().add(0, mappingJacksonHttpMessageConverter());
        restTemplate.setErrorHandler(new ErrorHandler());

        return restTemplate;
    }

    .....

Please...help me solve this problem...

Answer 1

This can be done in the following way, though it's not recommended for production use

have your custom RestTemplateTransportClientFactory implementation, for example use the following code, (used eureka-client-1.9.17 and spring 2.2.2.RELEASE)

@Bean
public RestTemplateDiscoveryClientOptionalArgs discoveryClientOptionalArgs() throws Exception {
    RestTemplateDiscoveryClientOptionalArgs args = new RestTemplateDiscoveryClientOptionalArgs();
    args.setHostnameVerifier(NoopHostnameVerifier.INSTANCE);
    args.setTransportClientFactories(new CustomRestTemplateTransportClientFactories());
    return args;
}

public class CustomRestTemplateTransportClientFactories extends RestTemplateTransportClientFactories {

    @Override
    public TransportClientFactory newTransportClientFactory(final EurekaClientConfig clientConfig,
            final Collection<Void> additionalFilters, final InstanceInfo myInstanceInfo,
            final Optional<SSLContext> sslContext, final Optional<HostnameVerifier> hostnameVerifier) {
        return new CustomRestTemplateTransportClientFactory();
    }
}

public class CustomRestTemplateTransportClientFactory extends RestTemplateTransportClientFactory {

    @Override
    public EurekaHttpClient newClient(EurekaEndpoint serviceUrl) {
        try {
            return new RestTemplateEurekaHttpClient(restTemplate(serviceUrl.getServiceUrl()),
                    serviceUrl.getServiceUrl());
        }
        catch (HttpClientException e) {
            e.printStackTrace();
        }
        return null;
    }

    private RestTemplate restTemplate(String serviceUrl) throws HttpClientException {
        /*
         * Inject your custom rest template
         */
        RestTemplate restTemplate = restTemplateConfig.restTemplate(null);
        try {
            URI serviceURI = new URI(serviceUrl);
            if (serviceURI.getUserInfo() != null) {
                String[] credentials = serviceURI.getUserInfo().split(":");
                if (credentials.length == 2) {
                    restTemplate.getInterceptors()
                            .add(new BasicAuthenticationInterceptor(credentials[0], credentials[1]));
                }
            }
        }
        catch (URISyntaxException ignore) {

        }

        restTemplate.getMessageConverters().add(0, mappingJacksonHttpMessageConverter());
        restTemplate.setErrorHandler(new ErrorHandler());

        return restTemplate;
    }
}

class ErrorHandler extends DefaultResponseErrorHandler {

    @Override
    protected boolean hasError(HttpStatus statusCode) {
        /**
         * When the Eureka server restarts and a client tries to sent a
         * heartbeat the server will respond with a 404. By default
         * RestTemplate will throw an exception in this case. What we want
         * is to return the 404 to the upstream code so it will send another
         * registration request to the server.
         */
        if (statusCode.is4xxClientError()) {
            return false;
        }
        return super.hasError(statusCode);
    }

}

Hope this will be helpful. Thanks.