Creating a Kafka Topic

Constraints

• The total number of partitions in topics is limited. When the partition quantity limit is reached, you can no longer create topics. The total number of partitions varies by instance specifications. For details, see Specifications.
• If an instance node is faulty, an internal service error may be reported when you query messages in a topic with only one replica. Therefore, you are not advised using a topic with only one replica.

Creating a Topic on the Console

1. Log in to the console.
2. Click in the upper left corner to select a region.
   

   Select the region where your Kafka instance is located.

3. Click and choose Middleware > Distributed Message Service (for Kafka) to open the console of DMS for Kafka.
4. Click the desired Kafka instance to view the instance details.
5. In the navigation pane, choose Topics. Then click Create Topic.
6. Enter a topic name, specify other parameters, and click OK.
   Figure 1 Creating a topic
   

   Table 2 Topic parameters

   Parameter	Description
   Topic Name	Customize a name that contains 3 to 200 characters, starts with a letter or underscore (_), and contains only letters, digits, periods (.), hyphens (-), and underscores (_). The name must be different from preset topics: __consumer_offsets __transaction_state __trace __connect-status __connect-configs __connect-offsets Once the topic is created, you cannot modify its name. NOTE: Due to the limitation of the Kafka kernel, topics whose names contain only period or underscore difference cannot be created. For example, assume that the Topic_1 topic is created, creating a topic named Topic.1 will fail and throw the Topic 'topic.1' collides with existing topics: topic_1 exception.
   Partitions	Number of partitions in the topic. If the number of partitions is the same as that of consumers, the larger the partitions, the higher the consumption concurrency. If this parameter is set to 1, messages will be retrieved in the FIFO order. Value range: 1 to 200 Default value: 3
   Replicas	A higher number of replicas delivers higher reliability. Data is automatically backed up on each replica. When one Kafka broker becomes faulty, data is still available on other brokers. If this parameter is set to 1, only one set of data is available. Value range: 1 to number of brokers NOTE: If an instance node is faulty, an internal service error may be reported when you query messages in a topic with only one replica. Therefore, you are not advised using a topic with only one replica.
   Aging Time (h)	The period that messages are retained for. Consumers must retrieve messages before this period ends. Otherwise, the messages will be deleted and can no longer be consumed. Value range: 1–720 Default value: 72
   Synchronous Replication	A message is returned to the client only after the message creation request has been received and the message has been acknowledged by all replicas. After enabling this, set the parameter acks to all or -1 in the configuration file or production code on the producer client. If there is only one replica, synchronous replication cannot be enabled.
   Synchronous Flushing	A message is immediately flushed to disk once it is produced, bringing higher reliability. When this option is disabled, a message is stored in the memory instead of being immediately flushed to disk once produced.
   Message Timestamp	Timestamp type of a message. Options: CreateTime: time when the producer created the message. LogAppendTime: time when the broker appended the message to the log.
   Max. Message Size	Maximum batch processing size allowed by Kafka. If message compression is enabled in the client configuration file or code of producers, this parameter indicates the size after compression. If this is increased and there are consumers older than 0.10.2, the consumers' fetch size must also be increased so that they can fetch record batches this large. Value range: 0 to 10,485,760
   Description	0–200 characters.

Creating a Topic on Kafka Manager

Log in to Kafka Manager, choose Topic > Create, and set parameters as prompted. To ensure performance, a partition number within 200 is recommended for each topic.

Figure 2 Creating a topic on Kafka Manager

If a topic name starts with a special character, for example, a number sign (#), monitoring data cannot be displayed.

Creating a Topic on the Client

If your client is v2.2 or later, you can use kafka-topics.sh to create topics and manage topic parameters.

• If a topic name starts with a special character, for example, a number sign (#), monitoring data cannot be displayed.
• For an instance with ciphertext access enabled, if allow.everyone.if.no.acl.found is set to false, topics cannot be created through the client.

• For a Kafka instance with ciphertext access disabled, run the following command in the /bin directory of the Kafka client:

  ./kafka-topics.sh --create --topic ${topic-name} --bootstrap-server ${connection-address} --partitions ${number-of-partitions} --replication-factor ${number-of-replicas}

  Parameter description:

  • topic-name: topic name, which can be customized.
  • connection-address: can be obtained from the Connection area on the Basic Information page on the Kafka console.
  • number-of-partitions: number of partitions in a topic. To ensure performance, a partition number within 200 is recommended for each topic.
  • number-of-replicas: number of replicas in a topic.

  Example:

  [root@ecs-kafka bin]# ./kafka-topics.sh --create --topic topic-01 --bootstrap-server 192.168.xx.xx:9092,192.168.xx.xx:9092,192.168.xx.xx:9092 --partitions 3 --replication-factor 3
  Created topic topic-01.
  [root@ecs-kafka bin]#

• For a Kafka instance with ciphertext access enabled, do as follows:
  1. (Optional) Modify the client configuration file.
     View Security Protocol in the Connection area on the Basic Information page on the Kafka console. The configuration settings vary depending on the protocol.

     • SASL_PLAINTEXT: Skip this step and go to 2 if the username and password are already set. Otherwise, create the ssl-user-config.properties file in the /config directory on the Kafka client and add the following content to the file:

       security.protocol=SASL_PLAINTEXT
       # If the SASL mechanism is SCRAM-SHA-512, configure as follows:
       sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required \
       username="**********" \
       password="**********";        
       sasl.mechanism=SCRAM-SHA-512
       # If the SASL mechanism is PLAIN, configure as follows:
       sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required \
       username="**********" \
       password="**********";        
       sasl.mechanism=PLAIN

       Parameter description: username and password are the ones you set when enabling ciphertext access for the first time or when creating a user.

     • SASL_SSL: Skip this step and go to 2 if the username, password, and SSL certificate are already set. Otherwise, create the ssl-user-config.properties file in the /config directory on the Kafka client and add the following content to the file:

       security.protocol=SASL_SSL
       ssl.truststore.location={ssl_truststore_path}
       ssl.truststore.password=dms@kafka
       ssl.endpoint.identification.algorithm=
       # If the SASL mechanism is SCRAM-SHA-512, configure as follows:
       sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required \
       username="**********" \
       password="**********";        
       sasl.mechanism=SCRAM-SHA-512
       # If the SASL mechanism is PLAIN, configure as follows:
       sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required \
       username="**********" \
       password="**********";        
       sasl.mechanism=PLAIN

       Parameter description:

       • ssl.truststore.location: path for storing the client.jks certificate. Even in Windows, you need to use slashes (/) for the certificate path. Do not use backslashes (\), which are used by default for paths in Windows. Otherwise, the client will fail to obtain the certificate.
       • ssl.truststore.password: server certificate password, which must be set to dms@kafka and cannot be changed.
       • ssl.endpoint.identification.algorithm: whether to verify the certificate domain name. This parameter must be left blank, which indicates disabling domain name verification.
       • username and password: username and password you set when enabling ciphertext access for the first time or when creating a user.
  2. Run the following command in the /bin directory of the Kafka client:

     ./kafka-topics.sh --create --topic ${topic-name} --bootstrap-server ${connection-address} --partitions ${number-of-partitions} --replication-factor ${number-of-replicas} --command-config ../config/ssl-user-config.properties 

     Parameter description:

     • topic-name: topic name, which can be customized.
     • connection-address: can be obtained from the Connection area on the Basic Information page on the Kafka console.
     • number-of-partitions: number of partitions in a topic. To ensure performance, a partition number within 200 is recommended for each topic.
     • number-of-replicas: number of replicas in a topic.

     Example:

     [root@ecs-kafka bin]# ./kafka-topics.sh --create --topic topic-01 --bootstrap-server 192.168.xx.xx:9093,192.168.xx.xx:9093,192.168.xx.xx:9093 --partitions 3 --replication-factor 3 --command-config ../config/ssl-user-config.properties
     Created topic topic-01.
     [root@ecs-kafka bin]#