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一般我们在使用kbs登陆hadoop服务时都直接在shell中调用kinit命令来获取凭证，这种方式简单直接，只要获取一次凭证之后都可以在该会话过程中重复访问。但是这种方式一个明显的问题就是如果在本次shell中会间隔调用不同的java程序，而这些程序需要访问不同权限的问题，需要在访问前调用各自的ktab文件获得授权。这中场景下情况会变得非常复杂，这时如果把kbs认证的过程移到java程序中就会简单很多，每个java程序中获取各自的凭证，及时多个进程同时运行也不会产生相互影响。我这里介绍两种java中获取kbs凭证的方法，分别使用 org.apache.hadoop.security.SecurityUtil 和 org.apache.hadoop.security.UserGroupInformation 两个类实现。
一、 使用ktab文件简单登录方式
登录操作函数
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/** * 尝试使用kerberos认证登录hfs *@params * conf: 配置，其中带有keytab相关配置属性 * keytab_KEY: 表示conf中代表keytab文件属性的键值 * principal_KEY: 表示conf中代表principal属性的键值 * @throws IOException */ static void tryKerberosLogin(Configuration conf, String keytab_KEY, String principal_KEY) throws IOException { boolean useSec = true; LOG.info("Hadoop Security enabled: " + useSec); if (!useSec) { return; } try { @SuppressWarnings("rawtypes") Class c = Class.forName("org.apache.hadoop.security.SecurityUtil"); // get method login(Configuration, String, String); @SuppressWarnings("unchecked") Method m = c.getMethod("login", Configuration.class, String.class, String.class); m.invoke(null, conf, keytab_KEY, principal_KEY); LOG.info("successfully authenticated with keytab"); } catch (Exception e) { LOG.error( "Flume failed when attempting to authenticate with keytab " + SimpleConfiguration.get().getKerberosKeytab() + " and principal '" + SimpleConfiguration.get().getKerberosPrincipal() + "'", e); return; } } |
配置
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... <property> <name>flume.security.kerberos.principal</name> <description></description> </property> <property> <name>flume.security.kerberos.keytab</name> <value>resources/flume.keytab</value> <description></description> </property> … |
Sample
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//调用例子 public FileSystem getFileSystem(Configuration conf) { String KEYFILE_key = "flume.security.kerberos.keytab"; String PRINCIPAL_key = "flume.security.kerberos.principal"; try { // 尝试用kerberos登录 tryKerberosLogin(conf, KEYFILE_key, PRINCIPAL_key); // 获取一个hdfs实例 instance = FileSystem.get( conf); } catch (IOException e) { LOG.error("try getFileSystem fail()", e); } catch (URISyntaxException e) { LOG.error("try getFileSystem fail()", e); } } return instance; } |
二、 通过UserGroupInformation获取代理用户方式
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package com.netease.backend.bigdata.wa.jobs; import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.Path; import org.apache.hadoop.security.UserGroupInformation; import org.apache.log4j.Logger; import org.hsqldb.lib.StringUtil; import com.netease.backend.bigdata.wa.core.ConfKeys; /** * 代理用户信息认证工具 * * @author zhouliangwei * */ public class ProxyUGI { private static Logger LOG = Logger.getLogger(ProxyUGI.class); private static UserGroupInformation instance = null; /** * 从Configuration中获取代理用户的相关配置，并获取UserGroupInformation * @return * @throws IOException */ public synchronized static UserGroupInformation getProxyUGI(Configuration conf) { if (instance != null) return instance; try { String username = conf.get(ConfKeys.MR_USER_NAME, ""); String proxyPrincipal = conf.get(ConfKeys.WDA_PROXY_PRINCIPAL, ""); String proxyKtab = conf.get(ConfKeys.WDA_PROXY_KEYTAB, ""); if (StringUtil.isEmpty(username) || StringUtil.isEmpty(proxyPrincipal) || StringUtil.isEmpty(proxyKtab)) { LOG.warn("config properties: [" + ConfKeys.MR_USER_NAME + ", " + ConfKeys.WDA_PROXY_PRINCIPAL + ", " + ConfKeys.WDA_PROXY_KEYTAB + "] in config file './conf/wda-core.xml' must be set!, quite use proxy mechanism"); return null; } instance = UserGroupInformation.createProxyUser(username, UserGroupInformation.loginUserFromKeytabAndReturnUGI( proxyPrincipal, proxyKtab)); } catch (IOException ex) { //just ignore; } return instance; } } |
调用方式
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... public static void main(final String[] args) throws Exception { UserGroupInformation ugi = ProxyUGI.getProxyUGI(); if (ugi != null) { ugi.doAs(new PrivilegedExceptionAction<EventJobClient>() { public EventJobClient run() throws Exception { EventJobClient mr = new EventJobClient(); int code = ToolRunner.run(mr, args); System.exit(code); return mr; } }); System.exit(1); } else { int exitCode = ToolRunner.run(new EventJobClient(), args); System.exit(exitCode); } } …. |
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