部署Eureka的时候出现一个很莫名其妙的问题，自定义端口后会一直报下面这个错误，但是用默认的8761端口又没有问题
2021-12-07 15:59:45.057 ERROR 20599 --- [get_localhost-9] c.n.e.cluster.ReplicationTaskProcessor : Network level connection to peer localhost; retrying after delay com.sun.jersey.api.client.ClientHandlerException: java.net.ConnectException: Connection refused (Connection refused) at com.sun.jersey.client.apache4.ApacheHttpClient4Handler.handle(ApacheHttpClient4Handler.java:187) ~[jersey-apache-client4-1.19.1.jar!/:1.19.1] at com.netflix.eureka.cluster.DynamicGZIPContentEncodingFilter.handle(DynamicGZIPContentEncodingFilter.java:48) ~[eureka-core-1.9.13.jar!/:1.9.13] at com.netflix.discovery.EurekaIdentityHeaderFilter.handle(EurekaIdentityHeaderFilter.java:27) ~[eureka-client-1.9.13.jar!/:1.9.13] at com.sun.jersey.api.client.Client.handle(Client.java:652) ~[jersey-client-1.19.1.jar!/:1.19.1] at com.sun.jersey.api.client.WebResource.handle(WebResource.java:682) ~[jersey-client-1.19.1.jar!/:1.19.1] at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74) ~[jersey-client-1.19.1.jar!/:1.19.1] at com.sun.jersey.api.client.WebResource$Builder.post(WebResource.java:570) ~[jersey-client-1.19.1.jar!/:1.19.1] at com.netflix.eureka.transport.JerseyReplicationClient.submitBatchUpdates(JerseyReplicationClient.java:117) ~[eureka-core-1.9.13.jar!/:1.9.13] at com.netflix.eureka.cluster.ReplicationTaskProcessor.process(ReplicationTaskProcessor.java:80) ~[eureka-core-1.9.13.jar!/:1.9.13] at com.netflix.eureka.util.batcher.TaskExecutors$BatchWorkerRunnable.run(TaskExecutors.java:193) [eureka-core-1.9.13.jar!/:1.9.13] at java.lang.Thread.run(Thread.java:748) [na:1.8.0_292] Caused by: java.net.ConnectException: Connection refused (Connection refused) at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_292] at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_292] at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_292] at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_292] at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_292] at java.net.Socket.connect(Socket.java:607) ~[na:1.8.0_292] at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:121) ~[httpclient-4.5.10.jar!/:4.5.10] at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180) ~[httpclient-4.5.10.jar!/:4.5.10] at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:144) ~[httpclient-4.5.10.jar!/:4.5.10] at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:134) ~[httpclient-4.5.10.jar!/:4.5.10] at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:605) ~[httpclient-4.5.10.jar!/:4.5.10] at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:440) ~[httpclient-4.5.10.jar!/:4.5.10] at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:835) ~[httpclient-4.5.10.jar!/:4.5.10] at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:118) ~[httpclient-4.5.10.jar!/:4.5.10] at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) ~[httpclient-4.5.10.jar!/:4.5.10] at com.sun.jersey.client.apache4.ApacheHttpClient4Handler.handle(ApacheHttpClient4Handler.java:173) ~[jersey-apache-client4-1.19.1.jar!/:1.19.1] ... 10 common frames omitted
几经周折感觉这个问题出的蛮扯淡，记录一下帮遇到同样问题的人避避坑。
原来我的配置(就是会报上述错误的配置)：
spring: application: name: eureka server: port: 7000 eureka: client: register-with-eureka: false fetch-registry: false
修改后不报错的配置：
spring: application: name: eureka server: port: 7000 eureka: instance: hostname: localhost client: register-with-eureka: false fetch-registry: false
就是添加了 hostname 这项配置。比较搞人的地方是这个地方只能配 localhost，配成其他值一样会报上述错误。
参考：
（2）使用Spring Cloud更改Eureka服务器的默认端口
