Jenkins启动报错解决

误删Jenkins权限管理插件，导致Jenkins重启直接报错！
如何恢复？且看本篇内容。

前情提要

为了对jenkins任务做权限管理，百度了网上各种教程，说是要安装Role-based Authorization Strategy插件，使用插件管理中project roles可以实现。于是乎下载安装、鼓捣一阵。发现没有project roles这部分内容！难道插件版本有问题？卸载之…接着出大问题，jenkins启不来了！！！

报错内容如下(有部分删减)：

com.thoughtworks.xstream.mapper.CannotResolveClassException: com.michelin.cio.hudson.plugins.rolestrategy.RoleBasedAuthorizationStrategy
	at com.thoughtworks.xstream.mapper.DefaultMapper.realClass(DefaultMapper.java:79)
	at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
	at com.thoughtworks.xstream.mapper.DynamicProxyMapper.realClass(DynamicProxyMapper.java:55)
	at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:30)
	......
Caused: jenkins.util.xstream.CriticalXStreamException: com.michelin.cio.hudson.plugins.rolestrategy.RoleBasedAuthorizationStrategy : com.michelin.cio.hudson.plugins.rolestrategy.RoleBasedAuthorizationStrategy
---- Debugging information ----
message             : com.michelin.cio.hudson.plugins.rolestrategy.RoleBasedAuthorizationStrategy
cause-exception     : com.thoughtworks.xstream.mapper.CannotResolveClassException
cause-message       : com.michelin.cio.hudson.plugins.rolestrategy.RoleBasedAuthorizationStrategy
class               : hudson.model.Hudson
required-type       : hudson.model.Hudson
converter-type      : hudson.util.RobustReflectionConverter
path                : /hudson/authorizationStrategy
line number         : 9
version             : not available
-------------------------------
	......
	at hudson.util.XStream2.unmarshal(XStream2.java:162)
	at hudson.util.XStream2.unmarshal(XStream2.java:133)
	at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1173)
	at hudson.XmlFile.unmarshal(XmlFile.java:180)
Caused: java.io.IOException: Unable to read C:\Users\Administrator\.jenkins\config.xml
	at hudson.XmlFile.unmarshal(XmlFile.java:183)
	at hudson.XmlFile.unmarshal(XmlFile.java:163)
	......
Caused: org.jvnet.hudson.reactor.ReactorException
	at org.jvnet.hudson.reactor.Reactor.execute(Reactor.java:282)
	at jenkins.InitReactorRunner.run(InitReactorRunner.java:48)
	......
Caused: hudson.util.HudsonFailedToLoad
	at hudson.WebAppMain$3.run(WebAppMain.java:250)

解决方案

（此处省略一万字的因为Jenkins启动失败导致的心理活动描写）内心平静下后，仔细观察报错内容，进行分析：

1. CannotResolveClassException: 无法对这个类com.michelin.cio.hudson.plugins.rolestrategy.RoleBasedAuthorizationStrategy做正确的处理
2. CriticalXStreamException: XStream？？ 这是在解析什么？？ 解析文件？？
3. Unable to read C:\Users\Administrator\.jenkins\config.xml： XStream在解析[config.xml]时遇到了无法处理的类[RoleBasedAuthorizationStrategy]

此时你可能不会想到一个问题，就是config.xml里面有什么内容？不好意思，我就打开了这个文件观察了一下，结果恍然大悟。

config.xml文件的内容是下面这个样子的，你有没有发现什么呢？

<?xml version='1.1' encoding='UTF-8'?>
<hudson>
  <disabledAdministrativeMonitors/>
  <version>2.204.1</version>
  <installStateName>RUNNING</installStateName>
  <numExecutors>2</numExecutors>
  <mode>NORMAL</mode>
  <useSecurity>true</useSecurity>
  <authorizationStrategy class="com.michelin.cio.hudson.plugins.rolestrategy.RoleBasedAuthorizationStrategy">
    <roleMap type="globalRoles">
      <role name="admin" pattern=".*">
        <permissions>
          <permission>hudson.model.Hudson.Read</permission>
          <permission>hudson.model.View.Delete</permission>
          <permission>hudson.model.Computer.Connect</permission>
          <permission>hudson.model.Item.Create</permission>
          <permission>hudson.model.Item.Workspace</permission>
          <permission>hudson.model.Computer.Create</permission>
          <permission>hudson.model.View.Configure</permission>
          <permission>hudson.model.Computer.Provision</permission>
          <permission>hudson.model.Computer.Build</permission>
          <permission>hudson.model.Item.Configure</permission>
          <permission>hudson.model.View.Read</permission>
          <permission>hudson.model.View.Create</permission>
          <permission>hudson.model.Hudson.Administer</permission>
          <permission>hudson.model.Item.Cancel</permission>
          <permission>hudson.model.Item.Delete</permission>
          <permission>hudson.model.Item.Read</permission>
          <permission>hudson.model.Computer.Configure</permission>
          <permission>hudson.model.Computer.Delete</permission>
          <permission>hudson.model.Item.Build</permission>
          <permission>hudson.model.Computer.Disconnect</permission>
          <permission>hudson.model.Item.Discover</permission>
        </permissions>
        <assignedSIDs>
          <sid>admin</sid>
        </assignedSIDs>
      </role>
      <role name="tester" pattern=".*">
        <permissions>
          <permission>hudson.model.Hudson.Read</permission>
        </permissions>
        <assignedSIDs/>
      </role>
    </roleMap>
    <roleMap type="slaveRoles"/>
    <roleMap type="projectRoles"/>
  </authorizationStrategy>
  <securityRealm class="hudson.security.HudsonPrivateSecurityRealm">
    <disableSignup>true</disableSignup>
    <enableCaptcha>false</enableCaptcha>
  </securityRealm>
  <disableRememberMe>false</disableRememberMe>
  <projectNamingStrategy class="jenkins.model.ProjectNamingStrategy$DefaultProjectNamingStrategy"/>
  <workspaceDir>${JENKINS_HOME}/workspace/${ITEM_FULL_NAME}</workspaceDir>
  <buildsDir>${ITEM_ROOTDIR}/builds</buildsDir>
  <markupFormatter class="hudson.markup.EscapedMarkupFormatter"/>
  <jdks/>
  <viewsTabBar class="hudson.views.DefaultViewsTabBar"/>
  <myViewsTabBar class="hudson.views.DefaultMyViewsTabBar"/>
  <clouds/>
  <scmCheckoutRetryCount>0</scmCheckoutRetryCount>
  <views>
    <hudson.model.AllView>
      <owner class="hudson" reference="../../.."/>
      <name>all</name>
      <filterExecutors>false</filterExecutors>
      <filterQueue>false</filterQueue>
      <properties class="hudson.model.View$PropertyList"/>
    </hudson.model.AllView>
  </views>
  <primaryView>all</primaryView>
  <slaveAgentPort>-1</slaveAgentPort>
  <label></label>
  <crumbIssuer class="hudson.security.csrf.DefaultCrumbIssuer">
    <excludeClientIPFromCrumb>false</excludeClientIPFromCrumb>
  </crumbIssuer>
  <nodeProperties/>
  <globalNodeProperties/>
</hudson>

从文件内容可以看出，这里面有权限插件模块的部分定义，你会发现报错的类就在xml定义了。
因为插件被卸载，这部分定义内容还在，所以启动也就出大问题。
只需要删除<authorizationStrategy>...</authorizationStrategy>这部分内容，jenkins就可以重新启动起来啦。

问题解决了，继续权限管理的设置，详情请看下篇文章~