解决办法：
到官网下载cloidbees-folder.hpi，放到 /usr/local/tomcat/webapps/jenkins/WEB-INF/detached-plugins目录下，重启tomcat即可
[[email protected] ~]# cd /usr/local/tomcat/webapps/jenkins/WEB-INF/detached-plugins
[[email protected] detached-plugins]# wget http://ftp.icm.edu.pl/packages/jenkins/plugins/cloudbees-folder/latest/cloudbees-folder.hpi
--2018-10-19 15:43:03-- http://ftp.icm.edu.pl/packages/jenkins/plugins/cloudbees-folder/latest/cloudbees-folder.hpi
[[email protected] detached-plugins]# /usr/local/tomcat/bin/startup.sh
Using CATALINA_BASE: /usr/local/tomcat
Using CATALINA_HOME: /usr/local/tomcat
Using CATALINA_TMPDIR: /usr/local/tomcat/temp
Using JRE_HOME: /usr/local/java
Using CLASSPATH: /usr/local/tomcat/bin/bootstrap.jar:/usr/local/tomcat/bin/tomcat-juli.jar
Tomcat started.