报错信息：

root@2324d2daa74d:~/jenkins# java -jar agent.jar -jnlpUrl http://192.168.1.18:8080/computer/k8s-node2/jenkins-agent.jnlp -secret d1f55f9ffd189eaaf4b8897b5cf92c263fb2e8724139d42e59ac275284a82643 -workDir "/root/jenkins"
Error: Unable to access jarfile agent.jar
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解决办法：

 1.复制jenkins页面的agent.jar包下载链接，先下载下来再执行启动命令

root@2324d2daa74d:~/jenkins# wget http://192.168.1.18:8080/jnlpJars/agent.jar
bash: wget: command not found
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 很有可能出现上面的情况，就是jenkins容器中没有内置wget等命令。

 2.通过Jenkins宿主机下载agent.jar包，拷贝至Jenkins容器中，再执行启动命令。

[root@k8s-master ~]# wget http://192.168.1.18:8080/jnlpJars/agent.jar
--2021-11-27 00:45:07--  http://192.168.1.18:8080/jnlpJars/agent.jar
正在连接 192.168.1.18:8080... 已连接。
已发出 HTTP 请求，正在等待回应... 200 OK
长度：1507326 (1.4M) [application/java-archive]
正在保存至: “agent.jar”

100%[===============================================================>] 1,507,326   --.-K/s 用时 0.03s

2021-11-27 00:45:07 (52.6 MB/s) - 已保存 “agent.jar” [1507326/1507326])

[root@k8s-master ~]# docker cp /root/agent.jar jenkins:/root/jenkins     //拷贝至Jenkins容器的/root/jenkins目录下
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3.在Jenkins容器中查看agent.jar包并执行启动命令

[root@k8s-master ~]# docker exec -it --user root jenkins /bin/bash

root@2324d2daa74d:~/jenkins# cd /root/jenkins

root@2324d2daa74d:~/jenkins# ls
agent.jar  

root@2324d2daa74d:~/jenkins# java -jar agent.jar -jnlpUrl http://192.168.1.18:8080/computer/k8s-node2/jenkins-agent.jnlp -secret d1f55f9ffd189eaaf4b8897b5cf92c263fb2e8724139d42e59ac275284a82643 -workDir "/root/jenkins"
Nov 26, 2021 4:50:25 PM org.jenkinsci.remoting.engine.WorkDirManager initializeWorkDir
INFO: Using /root/jenkins/remoting as a remoting work directory
Nov 26, 2021 4:50:25 PM org.jenkinsci.remoting.engine.WorkDirManager setupLogging
INFO: Both error and output logs will be printed to /root/jenkins/remoting
Nov 26, 2021 4:50:25 PM hudson.remoting.jnlp.Main createEngine
INFO: Setting up agent: k8s-node2
Nov 26, 2021 4:50:25 PM hudson.remoting.jnlp.Main$CuiListener <init>
INFO: Jenkins agent is running in headless mode.
Nov 26, 2021 4:50:25 PM hudson.remoting.Engine startEngine
INFO: Using Remoting version: 4.10
Nov 26, 2021 4:50:25 PM org.jenkinsci.remoting.engine.WorkDirManager initializeWorkDir
INFO: Using /root/jenkins/remoting as a remoting work directory
Nov 26, 2021 4:50:25 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Locating server among [http://192.168.1.18:8080/]
Nov 26, 2021 4:50:25 PM org.jenkinsci.remoting.engine.JnlpAgentEndpointResolver resolve
INFO: Remoting server accepts the following protocols: [JNLP4-connect, Ping]
Nov 26, 2021 4:50:25 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Agent discovery successful
  Agent address: 192.168.1.18
  Agent port:    50000
  Identity:      f0:e1:b2:8d:35:66:e5:34:1e:7f:4b:9c:0c:06:a1:f0
Nov 26, 2021 4:50:25 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Handshaking
Nov 26, 2021 4:50:25 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Connecting to 192.168.1.18:50000
Nov 26, 2021 4:50:25 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Trying protocol: JNLP4-connect
Nov 26, 2021 4:50:25 PM org.jenkinsci.remoting.protocol.impl.BIONetworkLayer$Reader run
INFO: Waiting for ProtocolStack to start.
Nov 26, 2021 4:50:25 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Remote identity confirmed: f0:e1:b2:8d:35:66:e5:34:1e:7f:4b:9c:0c:06:a1:f0
Nov 26, 2021 4:50:26 PM hudson.remoting.jnlp.Main$CuiListener status
INFO: Connected      //连接成功
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----->在执行jenkins节点启动命令时，应该换成nohup 启动命令 &的方式，这样可以让它后台运行，不至于占用终端。

 现在Jenkins的node节点已经成功添加了！

↓↓↓↓↓↓

 最近刚申请了个微信公众号，上面也会分享一些运维知识，大家点点发财手关注一波，感谢大家。 【原创公众号】：非著名运维 【福利】：公众号回复 “资料” 送运维自学资料大礼包哦！