Spring Cloud Netflix Eureka client no longer registers proper port when server.port set to random (ie 0)

Describe the bug Like already described in Issue3294 this issue still remains in newer versions.

Sample You can check my github repository if you need a further test.

spring-boot-starter-parent: 2.3.1.RELEASE spring-cloud-starter-netflix-eureka-server: 2.2.3.RELEASE spring-cloud: Hoxton.SR6

spring-boot-starter-parent: 2.3.1.RELEASE spring-cloud-netflix-eureka-client: 2.2.3.RELEASE.jar spring-cloud.version: Hoxton.SR6

Comment From: spencergibb

Can you describe what "no longer registers proper port" means? What does /eureka/apps say?

Comment From: kleenxcoder

Sure!

Assuming I make use of random port assignment for my eureka client, my application.properties hast set "server.port=0". In my current case the service uses port 49270.

Looking at eureka sever I can see one registered service "UP (1) - ..local:hello-service:0" under section "Instances currently registered with Eureka" I would expect to see "UP (1) - ..local:hello-service:49270" this what happens when I set server.port=49270 manually.

When I start the service a second time and runs on port 49271 the eureka server does not display a second registered server.

Hope this helps

Comment From: blueiceprj

Hi,

I have also this problem on my project.

server.port=${random.int(5000,5100)} // -> 5095

But the gateway and the registery services looking at this address : http://XXXXXXXX:5062

Comment From: blueiceprj

I found a solution about that issue and helped me.

https://www.javacodemonk.com/setting-a-random-port-in-spring-boot-application-at-startup-87022e01

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.SocketUtils;
import org.springframework.util.StringUtils;

public class SpringBootUtil {
    final static Logger log = LoggerFactory.getLogger(SpringBootUtil.class);

    public static void setRandomPort(int minPort, int maxPort) {
        try {
            final String userDefinedPort = System.getProperty("server.port", System.getenv("SERVER_PORT"));
            if(StringUtils.isEmpty(userDefinedPort)) {
                final int port = SocketUtils.findAvailableTcpPort(minPort, maxPort);  
                System.setProperty("server.port", String.valueOf(port));
                log.info("Random Server Port is set to {}.", port);
            }
        } catch( final IllegalStateException e) {
            log.warn("No port available in range 5000-5100. Default embedded server configuration will be used.");
        }
    }
}

And

SpringBootUtil.setRandomPort(5000, 5500); 
final SpringApplication app = new SpringApplication(DemoServiceApp.class);

Comment From: kleenxcoder

Seems like this is not an issue and works as designed. My solution/workaround is setting eureka instance-id manually eureka.instance.instanceId=${spring.cloud.client.hostname}:${spring.application.name}:${spring.application.instance_id:${random.value}}

Comment From: yongschoi

// random server port server.port = 0

// application name spring.application.name = app-xxx

// random eureka instance name eureka.instance.instanceId = ${spring.application.name}:${random.value}