Take SpringCloud as an example, hope the service will generate a dynamic instance ID based on some information after startup

That isapplication.yamlConfigured inEurekaConfiguration

eureka:
  instance:
    instance-id: ID

If we want to randomly generate one when the service startsinstance-id, First find

can useBeanPostProcessorModify Bean after instantiationeureka.instanceThe Bean to which this property is bound is passed inapplication.yaml Hold downCtril + left buttonClick to findorg.springframework.cloud.netflix.eureka.EurekaInstanceConfigBean。

Then use the post processor to adjust the attributes after instantiation

@Component
public class EurekaConfigBeanPostProcessor implements BeanPostProcessor  {
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof EurekaInstanceConfigBean) {
            EurekaInstanceConfigBean properties = (EurekaInstanceConfigBean) bean;
            String instanceId = properties.getInstanceId();
            System.out.println("Old InstanceID:      " + instanceId);
            instanceId =  UUID.randomUUID().toString();
            // modify ID
            properties.setInstanceId(instanceId);
        }
        return null;
    }
}

In this way, we can see our customized ID in the registry.

Here is mainly to find the Config object corresponding to the configuration in the configuration file.

The following is an example of SpringCloud consul dynamically modifying the instance ID, the configuration example of Consul isorg.springframework.cloud.consul.discovery.ConsulDiscoveryPropertiesclass:

@Component
public class ConsulConfigPostProcessorDemo implements BeanPostProcessor  {

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof ConsulDiscoveryProperties) {
            
            ConsulDiscoveryProperties properties = (ConsulDiscoveryProperties) bean;
            String instanceId = properties.getInstanceId();
            System.out.println("InstanceID:      " + instanceId);
            instanceId += "__MODIFY";
            properties.setInstanceId(instanceId);
        }
        return null;
    }
}

reference

[1]. Spring BeanpostProcessor interface implementation Demo