我在同一台服务器上运行Jenkins Master& 。K8s-MasterJenkins 通过 tomcat Apache 运行（不在 K8s 集群上）。我有另一台服务器K8s-Worker-Node，在安装的两个服务器CentOS-8操作系统上。我已经配置Jenkins Kubernetes Plugin version - 1.26.4但是在运行管道作业时我总是遇到错误，下面是 K8s 集群 Jenkins 代理 pod 日志。
[root@K8s-Master /]# kubectl logs -f pipeline-test-33-sj6tl-r0clh-g559d -c jnlp
Aug 08, 2020 8:37:21 AM hudson.remoting.jnlp.Main createEngine
INFO: Setting up agent: pipeline-test-33-sj6tl-r0clh-g559d
Aug 08, 2020 8:37:21 AM hudson.remoting.jnlp.Main$CuiListener <init>
INFO: Jenkins agent is running in headless mode.
Aug 08, 2020 8:37:21 AM hudson.remoting.Engine startEngine
INFO: Using Remoting version: 4.3
Aug 08, 2020 8:37:21 AM org.jenkinsci.remoting.engine.WorkDirManager initializeWorkDir
INFO: Using /home/jenkins/agent/remoting as a remoting work directory
Aug 08, 2020 8:37:21 AM org.jenkinsci.remoting.engine.WorkDirManager setupLogging
INFO: Both error and output logs will be printed to /home/jenkins/agent/remoting
Aug 08, 2020 8:37:21 AM hudson.remoting.jnlp.Main$CuiListener status
INFO: Locating server among [http://jenkins-serverjenkins/]
Aug 08, 2020 8:37:41 AM hudson.remoting.jnlp.Main$CuiListener error
SEVERE: Failed to connect to http://jenkins-server/jenkins/tcpSlaveAgentListener/: jenkins-server
java.io.IOException: Failed to connect to http://jenkins-serverjenkins/tcpSlaveAgentListener/: jenkins-server
at org.jenkinsci.remoting.engine.JnlpAgentEndpointResolver.resolve(JnlpAgentEndpointResolver.java:217)
at hudson.remoting.Engine.innerRun(Engine.java:693)
at hudson.remoting.Engine.run(Engine.java:518)
Caused by: java.net.UnknownHostException: jenkins-server
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:607)
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:1226)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1162)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1056)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:990)
at org.jenkinsci.remoting.engine.JnlpAgentEndpointResolver.resolve(JnlpAgentEndpointResolver.java:214)
... 2 more
以下设置配置已启用。
Manage Jenkins --> Configure Global Security --> Agents Random [Enabled]
我能够成功地从我的 Jenkins 通信到 K8s 主集群（在 Jenkins Cloud 部分验证）。
即使在 K8s master 中，所有命名空间 pod 都在运行。weave-net安装了 CNI，不知道在通过 Jenkins 进行代理配置时导致问题的原因。
我的 Jenkins/K8s master & K8s-Worker-Node/etc/hosts如下。
# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
75.76.77.5 jenkins-server jenkins-server.company.domain.com
75.76.77.6 k8s-node-1 k8s-node-1.company.domain.com
下面是进入 K8s-Worker 节点的输出。从 K8s-worker 节点连接 jenkins-master 看起来没有问题。
# curl -I http://jenkins-server/jenkins/tcpSlaveAgentListener/
HTTP/1.1 200
Server: nginx/1.14.1
Date: Fri, 28 Aug 2020 06:13:34 GMT
Content-Type: text/plain;charset=UTF-8
Connection: keep-alive
Cache-Control: private
Expires: Thu, 01 Jan 1970 00:00:00 GMT
X-Content-Type-Options: nosniff
X-Hudson-JNLP-Port: 40021
X-Jenkins-JNLP-Port: 40021
X-Instance-Identity: MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnkgz8Av2x8R9R2KZDzWm1K11O01r7VDikW48rCNQlgw/pUeNSPJu9pv7kH884tOE65GkMepNdtJcOFQFtY1qZ0sr5y4GF5TOc7+U/TqfwULt60r7OQlKcrsQx/jJkF0xLjR+xaJ64WKnbsl0AiZhd8/ynk02UxFXKcgwkEP2PGpGyQ1ps5t/yj6ueFiPAHX2ssK8aI7ynVbf3YyVrtFOlqhnTy11mJFoLAZnpjYRCJsrX5z/xciVq5c2XmEikLzMpjFl0YBAsDo7JL4eBUwiBr64HPcSKrsBBB9oPE4oI6GkYUCAni8uOLfzoNr9B1eImaETYSdVPdSKW/ez/OeHjQIDAQAB
X-Jenkins-Agent-Protocols: JNLP4-connect, Ping
X-Remoting-Minimum-Version: 3.14
# curl http://jenkins-server:40021/
Jenkins-Agent-Protocols: JNLP4-connect, Ping
Jenkins-Version: 2.235.3
Jenkins-Session: 4455fd45
Client: 75.76.77.6
Server: 75.76.77.5
Remoting-Minimum-Version: 3.14
看起来 Kubernetes DNS 没有解析名称。因此，任何解决此问题的指针都会有所帮助。谢谢。