问题描述：
使用Kafka客户端通过21007端口访问开启Kerberos的集群报以下错误：
javax.security.sasl.SaslException: An error: (java.security.PrivilegedActionException: javax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - UNKNOWN_SERVER)]) occurred when evaluating SASL token received from the Kafka Broker. This may be caused by Java's being unable to resolve the Kafka Broker's hostname correctly. You may want to try to adding '-Dsun.net.spi.nameservice.provider.1=dns,sun' to your client's JVMFLAGS environment. Users must configure FQDN of kafka brokers when authenticating using SASL and `socketChannel.socket().getInetAddress().getHostName()` must match the hostname in `principal/hostname@realm` Kafka Client will go to AUTH_FAILED state.
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator.createSaslToken(SaslClientAuthenticator.java:293)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator.sendSaslToken(SaslClientAuthenticator.java:210)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator.authenticate(SaslClientAuthenticator.java:178)
at org.apache.kafka.common.network.KafkaChannel.prepare(KafkaChannel.java:64)
at org.apache.kafka.common.network.Selector.pollSelectionKeys(Selector.java:338)
at org.apache.kafka.common.network.Selector.poll(Selector.java:291)
at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:260)
at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:236)
at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:135)
at java.lang.Thread.run(Thread.java:745)
Caused by: javax.security.sasl.SaslException: GSS initiate failed
at com.sun.security.sasl.gsskerb.GssKrb5Client.evaluateChallenge(GssKrb5Client.java:211)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator$2.run(SaslClientAuthenticator.java:275)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator$2.run(SaslClientAuthenticator.java:273)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.kafka.common.security.authenticator.SaslClientAuthenticator.createSaslToken(SaslClientAuthenticator.java:273)
... 9 common frames omitted
Caused by: org.ietf.jgss.GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - UNKNOWN_SERVER)
at sun.security.jgss.krb5.Krb5Context.initSecContext(Krb5Context.java:770)
at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:248)
at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:179)
at com.sun.security.sasl.gsskerb.GssKrb5Client.evaluateChallenge(GssKrb5Client.java:192)
... 14 common frames omitted
Caused by: sun.security.krb5.KrbException: Server not found in Kerberos database (7) - UNKNOWN_SERVER
at sun.security.krb5.KrbTgsRep.
(KrbTgsRep.java:73) at sun.security.krb5.KrbTgsReq.getReply(KrbTgsReq.java:259)
at sun.security.krb5.KrbTgsReq.sendAndGetCreds(KrbTgsReq.java:270)
at sun.security.krb5.internal.CredentialsUtil.serviceCreds(CredentialsUtil.java:302)
at sun.security.krb5.internal.CredentialsUtil.acquireServiceCreds(CredentialsUtil.java:120)
at sun.security.krb5.Credentials.acquireServiceCreds(Credentials.java:458)
at sun.security.jgss.krb5.Krb5Context.initSecContext(Krb5Context.java:693)
... 17 common frames omitted
Caused by: sun.security.krb5.Asn1Exception: Identifier doesn't match expected value (906)
at sun.security.krb5.internal.KDCRep.init(KDCRep.java:140)
at sun.security.krb5.internal.TGSRep.init(TGSRep.java:65)
at sun.security.krb5.internal.TGSRep.
(TGSRep.java:60) at sun.security.krb5.KrbTgsRep.
(KrbTgsRep.java:55) ... 23 common frames omitted
刚开始遇到报访问timeout或者程序运行卡着看不到或者看到很少的报错信息，后来在项目里添加了日志相关依赖包，才看到比较完整的错误信息。
参考日志依赖：
ch.qos.logback logback-core
1.2.3
ch.qos.logback lagback-classic
1.2.3
org.slf4j slf4j-api
1.7.26
解决方法：
通过报错信息确认可能是服务名称不对，查看KDCServer日志发现：
账号名@xxxx.com for kafka/hadoop.hadoop.com@xxxx.com, Server not found in Kerveros database
对比访问正常的日志使用的服务名是：
kafka/hadoop.xxxx.com@xxxx.com
后在创建Kafka生产者时添加配置项：
kerberos.domain.name = hadoop.xxxx.com
问题解决
