Problem of Creating Topics in Kafka with Kerberos

Hi,

After enabled Kerberos using Ambari, I got problem creating topics in Kafka using the kafka-topics.sh script. The topic was created, but its status is wrong without leader. It seems the topic is created with PLAINTEXT, while there is only PLAINTEXTSASL broker in the cluster after enabled Kerberos. The only configuration change I made is to chagne broker listener from 'PLAINTEXT://localhost:6667' to 'PLAINTEXTSASL://localhost:6667'. As posted in this question, I also changed the kafka-topics.sh to make it work with Kerberos. I am using HDP2.5.3.

1. $ ./kafka-topics.sh --zookeeper ip-10-0-0-149.ap-northeast-1.compute.internal --create --partitions 1 --replication-factor 1 --topic mytopic
2. Created topic "mytopic".
3. $ ./kafka-topics.sh --zookeeper ip-10-0-0-149.ap-northeast-1.compute.internal --describe --topic mytopic
4. Topic:mytopic PartitionCount:1 ReplicationFactor:1 Configs:
5. Topic: mytopic Partition: 0 Leader: none Replicas: 1001 Isr:

 

 

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个解答，截止mthiele  · 2017年01月23日 02:24

When you use a script, command, or API to create a topic, an entry is created under ZooKeeper. The only user with access to ZooKeeper is the service account running Kafka (by default, kafka). Therefore, the first step toward creating a Kafka topic on a secure cluster is to run kinit, specifying the Kafka service keytab. The second step is to create the topic.

1. Run kinit, specifying the Kafka service keytab. For example:

   kinit -k -t /etc/security/keytabs/kafka.service.keytab kafka/c6401.ambari.apache.org@EXAMPLE.COM

2. Next, create the topic. Run the kafka-topics.sh command-line tool with the following options:

   /bin/kafka-topics.sh --zookeeper <hostname>:<port> --create --topic <topic-name> --partitions <number-of-partitions> --replication-factor <number-of-replicating-servers>

   For example:

   1. /bin/kafka-topics.sh --zookeeper c6401.ambari.apache.org:2181 --create --topic test_topic --partitions 2 --replication-factor 2
   2. Created topic "test_topic".

 

 

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个解答，截止yjiang  · 2017年01月26日 10:23

@dbains, @mthiele, @Daniel Kozlowski,

Thank you. It works when created as kafka user.

To summarize all the steps -- from Ambari configs, to creating topic, granting permission and testing on kafka console producer/consumer scripts, I created this article Step by Step Recipe for Securing Kafka with Kerberos. Hope it saves others' time :-)

 

 

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个解答，截止amankumbare  · 2017年03月07日 16:59

@yjiang

If you try to create a topic as a non kafka user, it creates a topic but with no Leader and ISR. This is a known issue. According to me, the reason behind this could be the zookeeper acl's. Once topic is created in zookeeper, its acl's will not allow kafka to read details about it.

If you want to create a topic as a non kafka user you need to workaround by following below steps :

If you are not using Ranger :

1. Make sure "auto.create.topic.enable = true"

2. Give acl's for the user from which you want to create a topic, for ex :

# bin/kafka-acls.sh --authorizer kafka.security.auth.SimpleAclAuthorizer --authorizer-properties zookeeper.connect=localhost:2181 --add --allow-principal User:Bob --producer --topic Test-topic

3. Do a kinit as a user from which you want to create topic.

4. Now try to produce messages to topic as that user :

# ./kafka-console-producer.sh --broker-list <hostname-broker>:6667 --topic Test-topic --security-protocol PLAINTEXTSASL

If you are using Ranger :

Instead of point 2 in above steps you will need to add a policy for the topic in ranger. Allow permissions for that user to produce, create, consumer. Restart kafka service. Then follow step 3 and 4 as mentioned above.

Hope this helps !!

 

 

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个解答，截止dbains  · 2017年01月23日 18:21

@yjiang Yes, please try creating the topic as kafka user because when we use kafka-topics.sh to create a test topic, what this script does is to create a node in zookeeper path - /broker/topics/test

then brokers thread gets notified that a new node is created and broker then creates actual data for topic test that is the metadata and physical data. But notice that Brokers are kafka/host@REALM, so if a user other than kafka creates a topic it gets permission for example world:anyone:r sasl:xyz:crdwa

So the new node that is created in zookeeper path will have these permissions. Now when the broker gets alerted and tries to create metadata and physical data for this new topic, it wont be able to because broker principal is kafka but topic's is xyz

 

 

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个解答，截止Daniel Kozlowski  · 2017年01月23日 08:47

@yjiang

To answer your question -

---------------

When you use a script, command, or API to create a topic, an entry is created under ZooKeeper. The only user with access to ZooKeeper is the service account running Kafka (by default, kafka). Therefore, the first step toward creating a Kafka topic on a secure cluster is to runkinit, specifying the Kafka service keytab. The second step is to create the topic.

----------------

See more in here: http://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.4.3/bk_secure-kafka-ambari/content/ch_secure-kafka-create-topics.html

I hope this helps.