nacos 1.4.1版本，在k8s里面，用一段时间就断开注册中心

[bingju328]

问题描述

1. 没有并发
2. 没有大文件传输
3. 网络会不稳定

当前的情况

过一两天就会断开连接，需要手动重启java服务，nacos服务一直正常运行，也没有日志

期望

可以配置，即使断开了，等正常的时候自动注册上去，就不用每次都重启应用了。

服务启动后注册成功，过一段时间，java应用就断开，在注册中心也看不到注册的服务了，然后必须重启java应用才会重新注册，java应用日志报错如下：

[mogu-admin:10.244.3.112:8080] [,] 2021-06-05 04:10:48.780 ERROR 1 [com.alibaba.nacos.client.Worker.longPolling.fixed-nacos.gulimall.svc.cluster.local_8848] com.alibaba.nacos.client.config.impl.ClientWorker [fixed-nacos.gulimall.svc.cluster.local_8848] [check-update] get changed dataId exception

java.net.UnknownHostException: nacos.gulimall.svc.cluster.local
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:589)
	at sun.net.NetworkClient.doConnect(NetworkClient.java:175)
	at sun.net.www.http.HttpClient.openServer(HttpClient.java:463)
	at sun.net.www.http.HttpClient.openServer(HttpClient.java:558)
	at sun.net.www.http.HttpClient.<init>(HttpClient.java:242)
	at sun.net.www.http.HttpClient.New(HttpClient.java:339)
	at sun.net.www.http.HttpClient.New(HttpClient.java:357)
	at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1220)
	at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1156)
	at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1050)
	at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:984)
	at sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(HttpURLConnection.java:1334)
	at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1309)
	at com.alibaba.nacos.common.http.client.request.JdkHttpClientRequest.execute(JdkHttpClientRequest.java:106)
	at com.alibaba.nacos.common.http.client.InterceptingHttpClientRequest.execute(InterceptingHttpClientRequest.java:53)
	at com.alibaba.nacos.common.http.client.NacosRestTemplate.execute(NacosRestTemplate.java:482)
	at com.alibaba.nacos.common.http.client.NacosRestTemplate.postForm(NacosRestTemplate.java:407)
	at com.alibaba.nacos.client.config.http.ServerHttpAgent.httpPost(ServerHttpAgent.java:155)
	at com.alibaba.nacos.client.config.http.MetricsHttpAgent.httpPost(MetricsHttpAgent.java:68)
	at com.alibaba.nacos.client.config.impl.ClientWorker.checkUpdateConfigStr(ClientWorker.java:441)
	at com.alibaba.nacos.client.config.impl.ClientWorker.checkUpdateDataIds(ClientWorker.java:408)
	at com.alibaba.nacos.client.config.impl.ClientWorker$LongPollingRunnable.run(ClientWorker.java:596)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

环境

spring配置

spring:
  application:
    name: mogu_web
  cloud:
    nacos:
      discovery:
        server-addr: ${nacos_config_discovery}
        heart-beat-timeout: 30000
        #        server-addr: nacos.gulimall.svc.cluster.local:8848
      config:
        server-addr: ${nacos_config}
        timeout: 30000
        #        server-addr: nacos.gulimall.svc.cluster.local:8848

其他配置

//k8s
1.15
//spring boot
<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.2.RELEASE</version>
        <relativePath/>
</parent>
//spring cloud alibaba
<parent>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-alibaba-starters</artifactId>
    <version>2.2.4.RELEASE</version>
</parent>
//nacos
<dependency>
      <groupId>com.alibaba.nacos</groupId>
      <artifactId>nacos-client</artifactId>
      <version>1.4.1</version>
      <scope>compile</scope>
</dependency>

问题排查

1. 先查了nacos日志，没有任何日志。
2. coredns 当时的日志

2021-06-04T23:23:39.938Z [ERROR] plugin/errors: 2 maya-apiserver-576587998d-7vpsj. AAAA: read udp 10.244.1.191:56724->192.168.8.1:53: i/o timeout
2021-06-04T23:25:39.971Z [ERROR] plugin/errors: 2 maya-apiserver-576587998d-7vpsj. AAAA: read udp 10.244.1.191:57593->192.168.8.1:53: i/o timeout

3. 然后dig cluster 发现正常，如下

root@hp:/# dig -t A nacos.gulimall.svc.cluster.local. @10.244.0.176
; <<>> DiG 9.11.3-1ubuntu1.15-Ubuntu <<>> -t A nacos.gulimall.svc.cluster.local. @10.244.0.176
;; global options: +cmd
;; Got answer:
;; WARNING: .local is reserved for Multicast DNS
;; You are currently testing what happens when an mDNS query is leaked to DNS
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49827
;; flags: qr rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: 8a69c8768d24fd61 (echoed)
;; QUESTION SECTION:
;nacos.gulimall.svc.cluster.local. IN	A

;; ANSWER SECTION:
nacos.gulimall.svc.cluster.local. 24 IN	A	10.97.100.187

;; Query time: 0 msec
;; SERVER: 10.244.0.176#53(10.244.0.176)
;; WHEN: Sat Jun 05 12:42:51 CST 2021
;; MSG SIZE  rcvd: 121