一文讲透hdfs的delegation token

2023-02-28 15:04:37 浏览数 (1)

【背景】


前一段时间总结了hadoop中的token认证、yarn任务运行中的token,其中也都提到了delegation token。而最近也遇到了一个问题,问题现象是:flink任务运行超过七天后,由于宿主机异常导致任务失败,继而触发任务的重试,但接连重试几次都是失败的,并且任务的日志也没有聚合,导致无法分析问题失败的原因。最后发现是和delegation token有关,本文就来总结下相关的原理。

【原理】


1. 什么是delegation token

先简单描述下为什么需要delegation token。在开启kerberos之后,服务之间交互前,都需要先向KDC认证获取对应的票据。而在一个yarn任务运行过程中可能会产生很多任务container,每个这样的任务container都可能会访问hdfs,由于访问前需要先获取票据来进行认证,那么这个时候KDC就很容易成为性能瓶颈。delegation token(委派token)就是为了减少不必要的认证工作而出现的。

2. delegation token在任务提交运行过程中的使用

任务提交运行过程中,delegation token相关的流程如下图所示:

1)首先,RM启动后,内部会创建一个服务线程专门用于处理token的更新

代码语言:javascript复制
// ResourceManager.java
protected void serviceInit(Configuration configuration) throws Exception {
    ...
    if (UserGroupInformation.isSecurityEnabled()) {
        delegationTokenRenewer = createDelegationTokenRenewer();
        rmContext.setDelegationTokenRenewer(delegationTokenRenewer);
    }
    ....
}

protected DelegationTokenRenewer createDelegationTokenRenewer() {
    return new DelegationTokenRenewer();
}

2)客户端申请delegation token

客户端在提交任务前,通常需要先向hdfs上传资源文件(包括运行所需的jar包等),在此过程中会向nn申请一个delegation token,并放到任务启动上下文中,然后向rm发送提交任务请求(请求中包含任务的启动上下文)。

下面是flink on yarn提交任务时的代码片段:

代码语言:javascript复制
// flink YarnClusterDescriptor.java
private ApplicationReport startAppMaster(...){
    // 开启kerberos的情况下,获取token
    if (UserGroupInformation.isSecurityEnabled()) {
      // set HDFS delegation tokens when security is enabled
      LOG.info("Adding delegation token to the AM container.");
      List<Path> yarnAccessList =
        ConfigUtils.decodeListFromConfig(
          configuration, YarnConfigOptions.YARN_ACCESS, Path::new);
      Utils.setTokensFor(
        amContainer,
        ListUtils.union(yarnAccessList, fileUploader.getRemotePaths()),
        yarnConfiguration);
    }
}

public static void setTokensFor(
    ContainerLaunchContext amContainer, List<Path> paths, Configuration conf)
    throws IOException {
    Credentials credentials = new Credentials();
    // for HDFS
    TokenCache.obtainTokensForNamenodes(credentials, paths.toArray(new Path[0]), conf);
    // for HBase
    obtainTokenForHBase(credentials, conf);
    // for user
    UserGroupInformation currUsr = UserGroupInformation.getCurrentUser();
    // 获取到的token 放到启动上下文中
    Collection<Token<? extends TokenIdentifier>> usrTok = currUsr.getTokens();
    for (Token<? extends TokenIdentifier> token : usrTok) {
        final Text id = new Text(token.getIdentifier());
        LOG.info("Adding user token "   id   " with "   token);
        credentials.addToken(id, token);
    }
    try (DataOutputBuffer dob = new DataOutputBuffer()) {
        credentials.writeTokenStorageToStream(dob);

        if (LOG.isDebugEnabled()) {
            LOG.debug("Wrote tokens. Credentials buffer length: "   dob.getLength());
        }

        ByteBuffer securityTokens = ByteBuffer.wrap(dob.getData(), 0, dob.getLength());
        amContainer.setTokens(securityTokens);
    }
}

// TokenCache.java
// 调用hadoop的接口 向nn请求token
public static void obtainTokensForNamenodes(
    Credentials credentials,
    Path[] ps, Configuration conf) 
    throws IOException {
    if (!UserGroupInformation.isSecurityEnabled()) {
        return;
    }
    obtainTokensForNamenodesInternal(credentials, ps, conf);
}

static void obtainTokensForNamenodesInternal(
    Credentials credentials,
    Path[] ps, 
    Configuration conf) 
    throws IOException {
    Set<FileSystem> fsSet = new HashSet<FileSystem>();
    for (Path p : ps) {
        fsSet.add(p.getFileSystem(conf));
    }
    String masterPrincipal = Master.getMasterPrincipal(conf);
    for (FileSystem fs : fsSet) {
        obtainTokensForNamenodesInternal(fs, credentials, conf, masterPrincipal);
    }
}

static void obtainTokensForNamenodesInternal(
    FileSystem fs,
    Credentials credentials, 
    Configuration conf, 
    String renewer)
    throws IOException {
    ...
    final Token<?> tokens[] = fs.addDelegationTokens(delegTokenRenewer, credentials);
    ...
}

// FileSystem.java
public Token<?>[] addDelegationTokens(
    final String renewer, Credentials credentials) 
    throws IOException {
    if (credentials == null) {
        credentials = new Credentials();
    }
    final List<Token<?>> tokens = new ArrayList<>();
    collectDelegationTokens(renewer, credentials, tokens);
    return tokens.toArray(new Token<?>[tokens.size()]);
}

private void collectDelegationTokens(
    final String renewer,
    final Credentials credentials,
    final List<Token<?>> tokens)
    throws IOException {
    final String serviceName = getCanonicalServiceName();
    // Collect token of the this filesystem and then of its embedded children
    if (serviceName != null) { // fs has token, grab it
        final Text service = new Text(serviceName);
        Token<?> token = credentials.getToken(service);
        if (token == null) {
            // 向NN 请求delegation token
            token = getDelegationToken(renewer);
            if (token != null) {
                tokens.add(token);
                credentials.addToken(service, token);
            }
        }
    }
    ...
}

3)RM将token添加到delegation token更新服务中

RM在处理客户端提交任务请求时,判断是否启用kerberos认证,如果启用则从任务启动上下文中解析出delegation token,并添加到delegation token更新服务中。在该服务中,会启动线程定时对delegation token进行更新。此后,继续向NM发送启动container的请求,delegation token则随启动上下文被带到NM中。

代码语言:javascript复制
// RMAppManager.java
protected void submitApplication(
    ApplicationSubmissionContext submissionContext, 
    long submitTime,
    String user)
    throws YarnException {
    ...
    if (UserGroupInformation.isSecurityEnabled()) {
        this.rmContext.getDelegationTokenRenewer().addApplicationAsync(
            applicationId,
            BuilderUtils.parseCredentials(submissionContext),
            submissionContext.getCancelTokensWhenComplete(),
            application.getUser(),
            BuilderUtils.parseTokensConf(submissionContext));
    }
    ...
}

4)NM使用delegation token

NM收到启动container的请求后,从请求(任务启动上下文)中解析出delegation token,并为该container构造一个对应的实例对象,同时将delegation token保存在该实例对象中,然后为该container进行资源本地化,即从hdfs中下载必须的资源文件,这里就会用到传递过来的delegation token。同时在任务结束时,如果需要进行任务日志聚合,仍旧会使用该delegation token将任务的日志上传到hdfs的指定路径。

另外,delegation token还会写入到持久化文件中,一方面用于NM的异常恢复,另一方面是将token传递给任务container进程以供使用。

3. delegation token的更新与生命周期

1)申请token时已经指定了token的最大生命周期

代码语言:javascript复制
// FSNamesystem.java
Token<DelegationTokenIdentifier> getDelegationToken(Text renewer) throws IOException {
    ...
    DelegationTokenIdentifier dtId = new DelegationTokenIdentifier(owner, renewer, realUser);
    token = new Token<DelegationTokenIdentifier>(dtId, dtSecretManager);
    ...
    return token;
}

// Token.java
public Token(T id, SecretManager<T> mgr) {
    password = mgr.createPassword(id);
    identifier = id.getBytes();
    kind = id.getKind();
    service = new Text();
}

// AbstractDelegationTokenSecretManager
protected synchronized byte[] createPassword(TokenIdent identifier) {
    long now = Time.now();
    identifier.setMaxDate(now   tokenMaxLifetime);
    ...
}

2)RM接收到任务提交请求后,先进行一次更新得到token的下次超时时间,然后再根据超时时间设置定时器时间触发进行更新。

代码语言:javascript复制
public void addApplicationSync(
    ApplicationId applicationId, 
    Credentials ts,
    boolean shouldCancelAtEnd, 
    String user) 
    throws IOException, InterruptedException {
    handleAppSubmitEvent(
        new DelegationTokenRenewerAppSubmitEvent(
            applicationId, ts, shouldCancelAtEnd, user, new Configuration()));
}

private void handleAppSubmitEvent(AbstractDelegationTokenRenewerAppEvent evt)
    throws IOException, InterruptedException {
    ...
    Credentials ts = evt.getCredentials();
    Collection<Token<?>> tokens = ts.getAllTokens();
    for (Token<?> token : tokens) {
        DelegationTokenToRenew dttr = allTokens.get(token);
        if (dttr == null) {
            dttr = new DelegationTokenToRenew(
                Arrays.asList(applicationId), 
                token, tokenConf, now, shouldCancelAtEnd, 
                evt.getUser());
            try {
                // 先进行一次更新
                renewToken(dttr)
            } catch (IOException ioe) {
                ...
            }
        }
        tokenList.add(dttr);
    }
    
    if (!tokenList.isEmpty()) {
        for (DelegationTokenToRenew dtr : tokenList) {
            DelegationTokenToRenew currentDtr = allTokens.putIfAbsent(dtr.token, dtr);
            if (currentDtr != null) {
                // another job beat us
                currentDtr.referringAppIds.add(applicationId);
                appTokens.get(applicationId).add(currentDtr);
            } else {
                appTokens.get(applicationId).add(dtr);
                setTimerForTokenRenewal(dtr);
            }
        }
    }
}

protected void renewToken(final DelegationTokenToRenew dttr)
    throws IOException {
    // need to use doAs so that http can find the kerberos tgt
    // NOTE: token renewers should be responsible for the correct UGI!
    try {
        // 更新delegation token 并得到下次超时时间
        dttr.expirationDate =
            UserGroupInformation.getLoginUser().doAs(
                new PrivilegedExceptionAction<Long>() {
                    @Override
                    public Long run() throws Exception {
                        return dttr.token.renew(dttr.conf);
                    }
                });
    } catch (InterruptedException e) {
        throw new IOException(e);
    }
    LOG.info("Renewed delegation-token= ["   dttr   "]");
}

protected void setTimerForTokenRenewal(DelegationTokenToRenew token)
    throws IOException {
    // calculate timer time
    long expiresIn = token.expirationDate - System.currentTimeMillis();
    if (expiresIn <= 0) {
        LOG.info("Will not renew token "   token);
        return;
    }
    long renewIn = token.expirationDate - expiresIn / 10; // little bit before the expiration
    // need to create new task every time
    RenewalTimerTask tTask = new RenewalTimerTask(token);
    token.setTimerTask(tTask); // keep reference to the timer

    renewalTimer.schedule(token.timerTask, new Date(renewIn));
    LOG.info(
        "Renew "   token   " in "   expiresIn   " ms, appId = "  
        token.referringAppIds);
}

再来看更新token的请求与处理细节:

代码语言:javascript复制
// 客户端发送更新请求
public long renew(Token<?> token, Configuration conf) throws IOException {
    Token<DelegationTokenIdentifier> delToken = (Token<DelegationTokenIdentifier>) token;
    ClientProtocol nn = getNNProxy(delToken, conf);
    try {
        return nn.renewDelegationToken(delToken);
    } catch (RemoteException re) {
        throw re.unwrapRemoteException(InvalidToken.class,
                AccessControlException.class);
    }
}

// 服务端的响应处理
long renewDelegationToken(Token<DelegationTokenIdentifier> token)
    throws InvalidToken, IOException {
    try {
        ...
        expiryTime = dtSecretManager.renewToken(token, renewer);
    } catch (AccessControlException ace) {
        ...
    }
    return expiryTime;
}

public synchronized long renewToken(
    Token<TokenIdent> token,
    String renewer) 
    throws InvalidToken, IOException {
    ByteArrayInputStream buf = new ByteArrayInputStream(token.getIdentifier());
    DataInputStream in = new DataInputStream(buf);
    TokenIdent id = createIdentifier();
    id.readFields(in);
    LOG.info(
        "Token renewal for identifier: "   formatTokenId(id)  
        "; total currentTokens "   currentTokens.size());

    long now = Time.now();
    if (id.getMaxDate() < now) {
        throw new InvalidToken(
            renewer   " tried to renew an expired token "  
            formatTokenId(id)   " max expiration date: "  
            Time.formatTime(id.getMaxDate())  
            " currentTime: "   Time.formatTime(now));
    }
    if ((id.getRenewer() == null) || (id.getRenewer().toString().isEmpty())) {
        throw new AccessControlException(
            renewer  
            " tried to renew a token "   formatTokenId(id)  
            " without a renewer");
    }
    if (!id.getRenewer().toString().equals(renewer)) {
        throw new AccessControlException(
            renewer  
            " tries to renew a token "   formatTokenId(id)  
            " with non-matching renewer "   id.getRenewer());
    }
    DelegationKey key = getDelegationKey(id.getMasterKeyId());
    if (key == null) {
        throw new InvalidToken(
            "Unable to find master key for keyId="  
            id.getMasterKeyId()  
            " from cache. Failed to renew an unexpired token "  
            formatTokenId(id)   " with sequenceNumber="  
            id.getSequenceNumber());
    }
    byte[] password = createPassword(token.getIdentifier(), key.getKey());
    if (!MessageDigest.isEqual(password, token.getPassword())) {
        throw new AccessControlException(
            renewer  
            " is trying to renew a token "  
            formatTokenId(id)   " with wrong password");
    }
    long renewTime = Math.min(id.getMaxDate(), now   tokenRenewInterval);
    String trackingId = getTrackingIdIfEnabled(id);
    DelegationTokenInformation info = 
        new DelegationTokenInformation(renewTime, password, trackingId);

    if (getTokenInfo(id) == null) {
        throw new InvalidToken(
            "Renewal request for unknown token "   formatTokenId(id));
    }
    updateToken(id, info);
    return renewTime;
}

3)token达到最大生命周期的处理

在定时器中,会捕获更新抛出的异常,并直接移除失效的token。

但是注意:在每次更新之前,会按需重新申请新的delegation token(后面再展开讲解)

代码语言:javascript复制
public void run() {
    if (cancelled.get()) {
        return;
    }

    Token<?> token = dttr.token;

    try {
        // 先判断是否需要申请新的token
        requestNewHdfsDelegationTokenIfNeeded(dttr);
        // if the token is not replaced by a new token, renew the token
        if (!dttr.isTimerCancelled()) {
            renewToken(dttr);
            setTimerForTokenRenewal(dttr);// set the next one
        } else {
            LOG.info("The token was removed already. Token = ["   dttr   "]");
        }
    } catch (Exception e) {
        LOG.error("Exception renewing token"   token   ". Not rescheduled", e);
        removeFailedDelegationToken(dttr);
    }
}

【问题分析】


来看看前面问题失败的相关日志,复盘分析下。

首先从NM的日志中发现任务在重试时,因为无法下载资源(到本地)导致无法启动任务,而下载资源失败的原因则是因为无效的token。

代码语言:javascript复制
2022-07-18 13:44:18,665 WARN org.apache.hadoop.ipc.Client: Exception encountered while connecting to the server : org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.security.token.SecretManager$InvalidToken): token (HDFS_DELEGATION_TOKEN token 4361 for hncscwc) can't be found in cache
2022-07-18 13:44:18,669 WARN org.apache.hadoop.yarn.server.nodemanager.containermanager.localizer.ResourceLocalizationService: { hdfs://hdfsHACluster/user/hncscwc/.flink/application_1637733238080_3800/application_1637733238080_38002636034628721129021.tmp, 1656925873322, FILE, null } failed: token (HDFS_DELEGATION_TOKEN token 4361 for hncscwc) can't be found in cache
org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.security.token.SecretManager$InvalidToken): token (HDFS_DELEGATION_TOKEN token 4361 for hncscwc) can't be found in cache
  at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1486)
  at org.apache.hadoop.ipc.Client.call(Client.java:1432)
  at org.apache.hadoop.ipc.Client.call(Client.java:1342)
  at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227)
  at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
  at com.sun.proxy.$Proxy15.getFileInfo(Unknown Source)
  at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:796)
  at sun.reflect.GeneratedMethodAccessor172.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:498)
  at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:411)
  at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:165)
  at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:157)
  at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
  at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:348)
  at com.sun.proxy.$Proxy16.getFileInfo(Unknown Source)
  at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:1649)
  at org.apache.hadoop.hdfs.DistributedFileSystem$27.doCall(DistributedFileSystem.java:1440)
  at org.apache.hadoop.hdfs.DistributedFileSystem$27.doCall(DistributedFileSystem.java:1437)
  at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
  at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1452)
  at org.apache.hadoop.yarn.util.FSDownload.copy(FSDownload.java:253)
  at org.apache.hadoop.yarn.util.FSDownload.access$000(FSDownload.java:63)
  at org.apache.hadoop.yarn.util.FSDownload$2.run(FSDownload.java:361)
  at org.apache.hadoop.yarn.util.FSDownload$2.run(FSDownload.java:359)
  at java.security.AccessController.doPrivileged(Native Method)
  at javax.security.auth.Subject.doAs(Subject.java:422)
  at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1922)
  at org.apache.hadoop.yarn.util.FSDownload.call(FSDownload.java:359)
  at org.apache.hadoop.yarn.util.FSDownload.call(FSDownload.java:62)
  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
  at java.lang.Thread.run(Thread.java:748)

为什么会出现无效的token,接着再看RM的日志。

代码语言:javascript复制
2022-07-04 17:11:13,400 INFO org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler: Application 'application_1637733238080_3800' is submitted without priority hence considering default queue/cluster priority: 0
2022-07-04 17:11:13,424 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657012273422; apps=[application_1637733238080_3800]]
2022-07-05 14:47:13,462 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657090033446; apps=[application_1637733238080_3800]]
2022-07-06 12:23:13,467 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657167793465; apps=[application_1637733238080_3800]]
2022-07-07 09:59:13,487 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657245553484; apps=[application_1637733238080_3800]]
2022-07-08 07:35:13,532 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657323313511; apps=[application_1637733238080_3800]]
2022-07-09 05:11:13,551 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657401073532; apps=[application_1637733238080_3800]]
2022-07-10 02:47:13,564 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657478833547; apps=[application_1637733238080_3800]]
2022-07-11 00:23:13,591 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800]]
2022-07-11 17:11:07,361 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800]]
2022-07-11 17:11:07,361 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renew Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800] in 6032 ms, appId = [application_1637733238080_3800]
2022-07-11 17:11:12,793 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800]]
2022-07-11 17:11:12,793 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renew Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800] in 600 ms, appId = [application_1637733238080_3800]
2022-07-11 17:11:13,337 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800]]
2022-07-11 17:11:13,337 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renew Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800] in 56 ms, appId = [application_1637733238080_3800]
2022-07-11 17:11:13,391 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renewed delegation-token= [Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800]]
2022-07-11 17:11:13,391 INFO org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Renew Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc);exp=1657530673393; apps=[application_1637733238080_3800] in 2 ms, appId = [application_1637733238080_3800]
2022-07-11 17:11:13,398 ERROR org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: Exception renewing tokenKind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:hdfsHACluster, Ident: (HDFS_DELEGATION_TOKEN token 4361 for hncscwc). Not rescheduled
org.apache.hadoop.security.token.SecretManager$InvalidToken: hadoop tried to renew an expired token (HDFS_DELEGATION_TOKEN token 4361 for hncscwc) max expiration date: 2022-07-11 17:11:13,393 0800 currentTime: 2022-07-11 17:11:13,394 0800
  at org.apache.hadoop.security.token.delegation.AbstractDelegationTokenSecretManager.renewToken(AbstractDelegationTokenSecretManager.java:499)
  at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.renewDelegationToken(FSNamesystem.java:5952)
  at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.renewDelegationToken(NameNodeRpcServer.java:675)
  at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.renewDelegationToken(ClientNamenodeProtocolServerSideTranslatorPB.java:1035)
  at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
  at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:447)
  at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:989)
  at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:850)
  at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:793)
  at java.security.AccessController.doPrivileged(Native Method)
  at javax.security.auth.Subject.doAs(Subject.java:422)
  at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1922)
  at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2489)

  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
  at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
  at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
  at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteException.java:121)
  at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteException.java:88)
  at org.apache.hadoop.hdfs.DFSClient$Renewer.renew(DFSClient.java:761)
  at org.apache.hadoop.security.token.Token.renew(Token.java:458)
  at org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer$1.run(DelegationTokenRenewer.java:601)
  at org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer$1.run(DelegationTokenRenewer.java:598)
  at java.security.AccessController.doPrivileged(Native Method)
  at javax.security.auth.Subject.doAs(Subject.java:422)
  at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1922)
  at org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer.renewToken(DelegationTokenRenewer.java:597)
  at org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer$RenewalTimerTask.run(DelegationTokenRenewer.java:531)
  at java.util.TimerThread.mainLoop(Timer.java:555)
  at java.util.TimerThread.run(Timer.java:505)
Caused by: org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.security.token.SecretManager$InvalidToken): hadoop tried to renew an expired token (HDFS_DELEGATION_TOKEN token 4361 for hncscwc) max expiration date: 2022-07-11 17:11:13,393 0800 currentTime: 2022-07-11 17:11:13,394 0800
  at org.apache.hadoop.security.token.delegation.AbstractDelegationTokenSecretManager.renewToken(AbstractDelegationTokenSecretManager.java:499)
  at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.renewDelegationToken(FSNamesystem.java:5952)
  at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.renewDelegationToken(NameNodeRpcServer.java:675)
  at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.renewDelegationToken(ClientNamenodeProtocolServerSideTranslatorPB.java:1035)
  at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
  at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:447)
  at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:989)
  at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:850)
  at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:793)
  at java.security.AccessController.doPrivileged(Native Method)
  at javax.security.auth.Subject.doAs(Subject.java:422)
  at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1922)
  at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2489)

  at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1486)
  at org.apache.hadoop.ipc.Client.call(Client.java:1432)
  at org.apache.hadoop.ipc.Client.call(Client.java:1342)
  at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227)
  at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
  at com.sun.proxy.$Proxy94.renewDelegationToken(Unknown Source)
  at 
org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.renewDelegationToken(ClientNamenodeProtocolTranslatorPB.java:964)
  at sun.reflect.GeneratedMethodAccessor277.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:498)
  at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:411)
  at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:165)
  at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:157)
  at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
  at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:348)
  at com.sun.proxy.$Proxy95.renewDelegationToken(Unknown Source)
  at org.apache.hadoop.hdfs.DFSClient$Renewer.renew(DFSClient.java:759)
  ... 10 more
2022-07-11 17:11:13,399 ERROR org.apache.hadoop.yarn.server.resourcemanager.security.DelegationTokenRenewer: removing failed delegation token for appid=[application_1637733238080_3800];t=ha-hdfs:hdfsHACluster

从上面的日志可以看到,任务从提交后,delegation token每天都有在更新,然而运行到第7天后,更新失败而失效。失效后,NN内部会删除无效的token,此时如果任务失败需要重试,或者任务结束需要进行日志聚合,都会继续使用该无效的token来操作hdfs,最终结果就是在NN中找不到对应的token而抛异常导致失败。

【问题解决】


要解决该问题,一种最简单直接的办法就是加大delegation token的最大生命周期时间。

但一开始觉得该办法略有些low,尤其对于flink长周期运行的实时任务的场景,是无法确定任务的运行时长的,因此也就无法确定设置token的最大生命周期。

因此,再次分析了源码,发现RM中对于将要过期(超过最大生命周期)的delegation token,会按需重新申请一个新的token,也就是定时器线程中token更新之前的requestNewHdfsDelegationTokenIfNeeded方法。

来看看具体的实现逻辑:

代码语言:javascript复制
private void requestNewHdfsDelegationTokenIfNeeded(
    final DelegationTokenToRenew dttr) 
    throws IOException, InterruptedException {

    // 拥有特权 并且 token类型为委派token 并且 快到最大生命周期
    if (hasProxyUserPrivileges &&
        dttr.maxDate - dttr.expirationDate < credentialsValidTimeRemaining &&
        dttr.token.getKind().equals(HDFS_DELEGATION_KIND)) {

        final Collection<ApplicationId> applicationIds;
        synchronized (dttr.referringAppIds) {
            applicationIds = new HashSet<>(dttr.referringAppIds);
            dttr.referringAppIds.clear();
        }
        // remove all old expiring hdfs tokens for this application.
        for (ApplicationId appId : applicationIds) {
            Set<DelegationTokenToRenew> tokenSet = appTokens.get(appId);
            if (tokenSet == null || tokenSet.isEmpty()) {
                continue;
            }
            Iterator<DelegationTokenToRenew> iter = tokenSet.iterator();
            synchronized (tokenSet) {
                while (iter.hasNext()) {
                    DelegationTokenToRenew t = iter.next();
                    if (t.token.getKind().equals(HDFS_DELEGATION_KIND)) {
                        iter.remove();
                        allTokens.remove(t.token);
                        t.cancelTimer();
                        LOG.info("Removed expiring token "   t);
                    }
                }
            }
        }
        LOG.info("Token= ("   dttr   ") is expiring, request new token.");
        requestNewHdfsDelegationTokenAsProxyUser(
            applicationIds, dttr.user,
            dttr.shouldCancelAtEnd);
    }
}

申请到新的token之后,会在RM内部进行更新,然后通过NM的心跳响应同步给NM。

代码语言:javascript复制
private void requestNewHdfsDelegationTokenAsProxyUser(
    ...
    // Get new hdfs tokens for this user
    Credentials credentials = new Credentials();
    Token<?>[] newTokens = obtainSystemTokensForUser(user, credentials);
    DataOutputBuffer dob = new DataOutputBuffer();
    credentials.writeTokenStorageToStream(dob);
    ByteBuffer byteBuffer = ByteBuffer.wrap(dob.getData(), 0, dob.getLength());
    for (ApplicationId applicationId : referringAppIds) {
        // 更新app的delegation token
        // 在NM心跳时进行同步
        rmContext.getSystemCredentialsForApps().put(applicationId, byteBuffer);
    }
} 

public NodeHeartbeatResponse nodeHeartbeat(NodeHeartbeatRequest request)
    throws YarnException, IOException {
    ...
    ConcurrentMap<ApplicationId, ByteBuffer> systemCredentials =
        rmContext.getSystemCredentialsForApps();
    if (!systemCredentials.isEmpty()) {
        nodeHeartBeatResponse.setSystemCredentialsForApps(systemCredentials);
    }
    ...
}

NM在心跳响应中解析出token并在内存中更新保存,后续任务重试启动资源本地化和任务结束触发日志聚合时会使用到。

注意:这里只提到了资源本地化和日志聚合时会使用到更新后的token,那么正在运行的任务会用到更新后的token吗?

答案是不会(至少是2.X版本不会)。主要是因为:token已经写入到持久化文件中,任务启动时读取该文件获取token并使用;delegation token在更新后没有写入到持久化文件中,即使可以写入(更新)到该文件,也需要有机制通知任务进程更新读取该文件才行。因此正在运行中的任务在token过期后继续操作hdfs仍旧会抛出异常。

另外,在3.X的最新版本中,注意到有相关代码的改动,应该是通知正在运行的container,但具体细节还未深入研究,后面有时间再调研。

【相关配置】


与delegation token相关的配置包括:

配置项名称

默认值

说明

dfs.namenode.delegation.key.update-interval

1天

token更新密钥的时间间隔

dfs.namenode.delegation.token.renew-interval

1天

token更新的时间间隔

dfs.namenode.delegation.token.max-lifetime

7天

token的最大生命周期

yarn.resourcemanager.delegation-token.alwys-cancel

false

RM结束时是否需要移除token

yarn.resourcemanager.proxy-user-privileges.enabled

false

是否开启特权在delegation token快过期时重新申请新的token

yarn.resourcemanager.system-credentials.valid-time-remaining

10800000

距离最大生命周期之前多长时间进行重新申请token的操作,单位毫秒

yarn.resourcemanager.delegation-token-renewer.thread-count

50

RM中delegation token更新线程的线程数

【总结】


本文通过一个实际的问题,并结合源码讲解了hadoop的delegation token的相关原理。

文中如有不对的地方,欢迎拍砖指正。

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