Eureka never unregisters a service

Question

I\'m currently facing an issue where Eureka does not unregister a registered service. I\'ve pulled the Eureka server example straight from git hub and made only one change,

Answer 1

I realized that self preservation mode was never actually being disabled. It turns out the actual property is

eureka.server.enableSelfPreservation=false

(See DefaultEurekaServerConfig Code), which I haven't found documented anywhere. This resolved my issue.

Answer 2

I made service de-registration work by setting the below values

Eureka server application.yml

eureka:
  server:
    enableSelfPreservation: false

Service application.yml

eureka:
  instance:
    leaseRenewalIntervalInSeconds: 1
    leaseExpirationDurationInSeconds: 2

The full example is here https://github.com/ExampleDriven/spring-cloud-eureka-example

Answer 3

After struggling a lot, finally I got solution if any service unregistered from Eureka server due to some issue. It will notify to the Admin by extending the HealthCallback of Eureka-Server APIs. Let Say Service-A register with Eureka. Hence Eureka Client is integrate with Service-A and Implement following Callbacks in Service A.

Service-A [Eureka-Client] Add following properties in properties files.

#Eureka Configuration
eureka.client.eureka-server-port=8761
eureka.client.register-with-eureka=true
eureka.client.healthcheck.enabled=false
eureka.client.prefer-same-zone-eureka=true
eureka.client.fetchRegistry=true
eureka.client.serviceUrl.defaultZone=${eurekaServerURL1}, ${eurekaServerURL2}
eureka.client.eureka.service-url.defaultZone=${eurekaServerURL1}, ${eurekaServerURL2}
eureka.instance.hostname=${hostname}
eureka.client.lease.duration=30
eureka.instance.lease-renewal-interval-in-seconds=30
eureka.instance.lease-expiration-duration-in-seconds=30

Add following java files.

@Component
public class EurekaHealthCheckHandler implements HealthCheckHandler, ApplicationContextAware, InitializingBean {


    static Logger logger = LoggerFactory.getLogger(EurekaHealthCheckHandler.class);

    private static final Map<Status, InstanceInfo.InstanceStatus> healthStatuses = new HashMap<Status, InstanceInfo.InstanceStatus>() {{
        put(Status.UNKNOWN, InstanceInfo.InstanceStatus.UNKNOWN);
        put(Status.OUT_OF_SERVICE, InstanceInfo.InstanceStatus.OUT_OF_SERVICE);
        put(Status.DOWN, InstanceInfo.InstanceStatus.DOWN);
        put(Status.UP, InstanceInfo.InstanceStatus.UP);
    }};

@Autowired
ComunocationService comunocationService ;
    private final CompositeHealthIndicator healthIndicator;

    private ApplicationContext applicationContext;

    public EurekaHealthCheckHandler(HealthAggregator healthAggregator) {
        Assert.notNull(healthAggregator, "HealthAggregator must not be null");
        this.healthIndicator = new CompositeHealthIndicator(healthAggregator);

        Health health = healthIndicator.health();
        logger.info(" =========== Testing =========== {}", health.toString() );
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    @Override
    public void afterPropertiesSet() throws Exception {

        final Map<String, HealthIndicator> healthIndicators = applicationContext.getBeansOfType(HealthIndicator.class);
        for (Map.Entry<String, HealthIndicator> entry : healthIndicators.entrySet()) {
            logger.info("======"+ entry.getKey() +"============= "+entry.getValue());
            healthIndicator.addHealthIndicator(entry.getKey(), entry.getValue());
        }
    }

    @Override
    public InstanceInfo.InstanceStatus getStatus(InstanceInfo.InstanceStatus instanceStatus) {
        logger.info("============== Custome Eureka Implementation ==================="+ getHealthStatus());
        return getHealthStatus();
    }

    protected InstanceInfo.InstanceStatus getHealthStatus() {
        final Status status = healthIndicator.health().getStatus();
        return mapToInstanceStatus(status);
    }

    protected InstanceInfo.InstanceStatus mapToInstanceStatus(Status status) {
        logger.info("============== Test Custome Eureka Implementation ==================={}", status);
        if(status.equals(InstanceInfo.InstanceStatus.UP)) {
            // Send mail after configured times
              comunocationService.sendEmail("ServiceName");
        }
        if(!healthStatuses.containsKey(status)) {
            return InstanceInfo.InstanceStatus.UNKNOWN;
        }
        return healthStatuses.get(status);
    }

    public void getstatusChangeListner() {
        ApplicationInfoManager.StatusChangeListener statusChangeListener = new ApplicationInfoManager.StatusChangeListener() {
            @Override
            public String getId() {
                return "statusChangeListener";
            }
            @Override
            public void notify(StatusChangeEvent statusChangeEvent) {
                if (InstanceStatus.DOWN == statusChangeEvent.getStatus() ||
                        InstanceStatus.DOWN == statusChangeEvent.getPreviousStatus()) {
                    // log at warn level if DOWN was involved
                    logger.warn("Saw local status change event {}", statusChangeEvent);
                } else {
                    logger.info("Saw local status change event {}", statusChangeEvent);
                }

            }
        };
    }


}

and

@Configuration
public class EurekaHealthCheckHandlerConfiguration {

    @Autowired(required = false)
    private HealthAggregator healthAggregator = new OrderedHealthAggregator();

    @Bean
    @ConditionalOnMissingBean
    public EurekaHealthCheckHandler eurekaHealthCheckHandler() {
        return new EurekaHealthCheckHandler(healthAggregator);
    }
}

This is absolutely working and well tested code