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Appendix: Kafka Configuration Options

Server.properties key-value pairs

Ambari configures the following Kafka values during the installation process. Settings are stored as key-value pairs stored in an underlying server.properties configuration file.

listeners

A comma-separated list of URIs that Kafka will listen on, and their protocols.

Required property with three parts:

<protocol>:<hostname>:<port>

Set <protocol> to SASL_PLAINTEXT, to specify the protocol that server accepts connections. SASL authentication will be used over a plaintext channel. Once SASL authentication is established between client and server, the session will have the client’s principal as an authenticated user. The broker can only accept SASL (Kerberos) connections, and there is no wire encryption applied. (Note: For a non-secure cluster, <protocol> should be set to PLAINTEXT.)

Set hostname to the hostname associated with the node you are installing. Kerberos uses this value and "principal" to construct the Kerberos service name. Specify hostname 0.0.0.0 to bind to all interfaces. Leave hostname empty to bind to the default interface.

Set port to the Kafka service port. When Kafka is installed using Ambari, the default port number is 6667.

Examples of legal listener lists::

listeners=SASL_PLAINTEXT://kafka1.host1.com:6667

listeners=PLAINTEXT://myhost:9092, TRACE://:9091, SASL_PLAINTEXT://0.0.0.0:9093

advertised.listeners

A list of listeners to publish to ZooKeeper for clients to use, if different than the listeners specified in the preceding section.

In IaaS environments, this value might need to be different from the interface to which the broker binds.

If advertised.listeners is not set, the value for listeners will be used.

Required value with three parts:

<protocol>:<hostname>:<port>

Set protocol to SASL_PLAINTEXT, to specify the protocol that server accepts connections. SASL authentication will be used over a plaintext channel. Once SASL authentication is established between client and server, the session will have the client’s principal as an authenticated user. The broker can only accept SASL (Kerberos) connections, and there is no wire encryption applied. (Note: For a non-secure cluster, <protocol> should be set to PLAINTEXT.)

Set hostname to the hostname associated with the node you are installing. Kerberos uses this and "principal" to construct the Kerberos service name.

Set port to the Kafka service port. When Kafka is installed using Ambari, the default port number is 6667.

For example:

advertised.listeners=SASL_PLAINTEXT://kafka1.host1.com:6667

security.inter.broker.protocol

Specifies the inter-broker communication protocol. In a Kerberized cluster, brokers are required to communicate over SASL. (This approach supports replication of topic data.) Set the value to SASL_PLAINTEXT:

security.inter.broker.protocol=SASL_PLAINTEXT

authorizer.class.name

Configures the authorizer class.

Set this value to kafka.security.auth.SimpleAclAuthorizer:

authorizer.class.name=kafka.security.auth.SimpleAclAuthorizer

For more information, see "Authorizing Access when Kerberos is Enabled."

principal.to.local.class

Transforms Kerberos principals to their local Unix usernames.

Set this value to kafka.security.auth.KerberosPrincipalToLocal:

principal.to.local.class=kafka.security.auth.KerberosPrincipalToLocal

super.users

Specifies a list of user accounts that will have all cluster permissions. By default, these super users have all permissions that would otherwise need to be added through the kafka-acls.sh script. Note, however, that their permissions do not include the ability to create topics through kafka-topics.sh, as this involves direct interaction with ZooKeeper.

Set this value to a list of user:<account> pairs separated by semicolons. Note that Ambari adds user:kafka when Kerberos is enabled.

Here is an example:

super.users=user:bob;user:alice
JAAS Configuration File for the Kafka Server

The Java Authentication and Authorization Service (JAAS) API supplies user authentication and authorization services for Java applications.

After enabling Kerberos, Ambari sets up a JAAS login configuration file for the Kafka server. This file is used to authenticate the Kafka broker against Kerberos. The file is stored at:

/usr/hdp/current/kafka-broker/config/kafka_server_jaas.conf

Ambari adds the following settings to the file. (Note: serviceName="kafka" is required for connections from other brokers.)

KafkaServer {
       com.sun.security.auth.module.Krb5LoginModule required
       useKeyTab=true
       keyTab="/etc/security/keytabs/kafka.service.keytab"
       storeKey=true
       useTicketCache=false
       serviceName="kafka" 
       principal="kafka/c6401.ambari.apache.org@EXAMPLE.COM";
       };
       
Client { // used for zookeeper connection
       com.sun.security.auth.module.Krb5LoginModule required
       useKeyTab=true
       keyTab="/etc/security/keytabs/kafka.service.keytab"
       storeKey=true
       useTicketCache=false
       serviceName="zookeeper"
       principal="kafka/c6401.ambari.apache.org@EXAMPLE.COM";
       };
Configuration Setting for the Kafka Producer

After enabling Kerberos, Ambari sets the following key-value pair in the server.properties file:

security.protocol=SASL_PLAINTEXT

JAAS Configuration File for the Kafka Client

After enabling Kerberos, Ambari sets up a JAAS login configuration file for the Kafka client. Settings in this file will be used for any client (consumer, producer) that connects to a Kerberos-enabled Kafka cluster. The file is stored at:

/usr/hdp/current/kafka-broker/config/kafka_client_jaas.conf

Ambari adds the following settings to the file. (Note: serviceName=kafka is required for connections from other brokers.)

[Note]Note

For command-line utilities like kafka-console-producer and kafka-console-consumer, use kinit. If you use a long-running process (for example, your own Producer), use keytab.

Kafka client configuration with keytab, for producers:

KafkaClient {
     com.sun.security.auth.module.Krb5LoginModule required
     useKeyTab=true
     keyTab="/etc/security/keytabs/storm.service.keytab"
     storeKey=true
     useTicketCache=false
     serviceName="kafka"
     principal="storm@EXAMPLE.COM";
    };

Kafka client configuration without keytab, for producers:

KafkaClient {
     com.sun.security.auth.module.Krb5LoginModule required
     useTicketCache=true
     renewTicket=true
     serviceName="kafka";
    };

Kafka client configuration for consumers:

KafkaClient {
     com.sun.security.auth.module.Krb5LoginModule required
     useTicketCache=true
     renewTicket=true
     serviceName="kafka";
     };