测试积点老人 发表于 2018-12-20 14:05:24

Jenkins获取JENKINS_HOME过程

JENKINS_HOME是Jenkins的主目录。在Jenkins上查看JENKINS_HOME:系统管理→系统设置→主目录(<JENKINS_URL>/configure页面)如上图帮助文档所示:Jenkins储存所有的数据文件在这个目录下. 你可以通过以下几种方式更改:

[*]使用你Web容器的管理工具设置JENKINS_HOME环境参数.
[*]在启动Web容器之前设置JENKINS_HOME环境变量.
[*](不推荐)更改Jenkins.war(或者在展开的Web容器)内的web.xml配置文件.
这个值在Jenkins运行时是不能更改的. 其通常用来确保你的配置是否生效.查看Jenkins的WEB-INF/web.xml,可以得知Jenkins主对象为hudson.WebAppMain:查看WebAppMain.java的源码,getHomeDir方法即用来确定Jenkins的主目录,其逻辑如下:鉴于Hudson是Jenkins的前身,所以为了兼容Jenkins主目录的名称有:JENKINS_HOME或HUDSON_HOMEprivate static final String[] HOME_NAMES = {"JENKINS_HOME","HUDSON_HOME"};
[*]首先,会在JNDI(可在web.xml配置文件中配置)中查找JENKINS_HOME或HUDSON_HOME
[*]其次会在系统属性中查找JENKINS_HOME或HUDSON_HOME
[*]接着会在环境变量中查找JENKINS_HOME或HUDSON_HOME
[*]最后,如果上述都找不到,会默认选择 $user.home/.jenkins为JENKINS_HOME($user.home/.hudson为HUDSON_HOME)
附:WebAppMain.java的getHomeDir方法源码/**
   * Determines the home directory for Jenkins.
   *
   * <p>
   * We look for a setting that affects the smallest scope first, then bigger ones later.
   *
   * <p>
   * People makes configuration mistakes, so we are trying to be nice
   * with those by doing {@link String#trim()}.
   *
   * <p>
   * @return the File alongside with some description to help the user troubleshoot issues
   */
    public FileAndDescription getHomeDir(ServletContextEvent event) {
      // check JNDI for the home directory first
      for (String name : HOME_NAMES) {
            try {
                InitialContext iniCtxt = new InitialContext();
                Context env = (Context) iniCtxt.lookup("java:comp/env");
                String value = (String) env.lookup(name);
                if(value!=null && value.trim().length()>0)
                  return new FileAndDescription(new File(value.trim()),"JNDI/java:comp/env/"+name);
                // look at one more place. See issue #1314
                value = (String) iniCtxt.lookup(name);
                if(value!=null && value.trim().length()>0)
                  return new FileAndDescription(new File(value.trim()),"JNDI/"+name);
            } catch (NamingException e) {
                // ignore
            }
      }

      // next the system property
      for (String name : HOME_NAMES) {
            String sysProp = System.getProperty(name);
            if(sysProp!=null)
                return new FileAndDescription(new File(sysProp.trim()),"System.getProperty(\""+name+"\")");
      }

      // look at the env var next
      for (String name : HOME_NAMES) {
            String env = EnvVars.masterEnvVars.get(name);
            if(env!=null)
                return new FileAndDescription(new File(env.trim()).getAbsoluteFile(),"EnvVars.masterEnvVars.get(\""+name+"\")");
      }

      // otherwise pick a place by ourselves

      String root = event.getServletContext().getRealPath("/WEB-INF/workspace");
      if(root!=null) {
            File ws = new File(root.trim());
            if(ws.exists())
                // Hudson <1.42 used to prefer this before ~/.hudson, so
                // check the existence and if it's there, use it.
                // otherwise if this is a new installation, prefer ~/.hudson
                return new FileAndDescription(ws,"getServletContext().getRealPath(\"/WEB-INF/workspace\")");
      }

      File legacyHome = new File(new File(System.getProperty("user.home")),".hudson");
      if (legacyHome.exists()) {
            return new FileAndDescription(legacyHome,"$user.home/.hudson"); // before rename, this is where it was stored
      }

      File newHome = new File(new File(System.getProperty("user.home")),".jenkins");
      return new FileAndDescription(newHome,"$user.home/.jenkins");
    }
此外,在Tomcat/logs/stdout_YYYYMMDD.log中有如下日志:Jenkins home directory: F:\JENKINS_HOME found at: EnvVars.masterEnvVars.get("JENKINS_HOME")
这与getHomeDir方法的相应源码对应:System.out.println("Jenkins home directory: "+home+" found at: "+describedHomeDir.description);

Miss_love 发表于 2021-1-5 14:55:20

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