Connecting to Kafka Using the Client (Ciphertext Access)

If you enable ciphertext access when creating an instance, SASL authentication will be required when your client connects to a Kafka instance.

For security purposes, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 is supported.

This section describes how to use an open-source Kafka client to access a Kafka instance if ciphertext access has been enabled for the instance. There are two scenarios. To access a Kafka instance across VPCs, see Accessing Kafka Using a VPC Endpoint Across VPCs. To access a Kafka instance using DNAT, see Accessing Kafka in a Public Network Using DNAT. To access an instance in your service code, see the Distributed Message Service Developer Guide.

Each Kafka broker allows a maximum of 1000 connections from each IP address by default. Excess connections will be rejected. You can change the limit by referring to Modifying Kafka Instance Configuration Parameters, that is, to modify parameter max.connections.per.ip.

Prerequisites

Accessing the Instance Using CLI

The following uses Linux as an example.

  1. Map hosts to IP addresses in the /etc/hosts file on the host where the client is located, so that the client can quickly parse the instance brokers.

    Set IP addresses to the instance connection addresses obtained in Prerequisites. Set hosts to the names of instance hosts. Specify a unique name for each host.

    For example:

    10.154.48.120 server01

    10.154.48.121 server02

    10.154.48.122 server03

  2. Decompress the Kafka CLI package.

    Access the directory where the CLI package is stored and run the following command to decompress the package:

    tar -zxf [kafka_tar]

    In the preceding command, [kafka_tar] indicates the name of the CLI package.

    For example:

    tar -zxf kafka_2.12-2.7.2.tgz

  3. Modify the Kafka CLI configuration file based on the SASL mechanism.

    • If PLAIN is used, find the consumer.properties and producer.properties files in the /config directory of the Kafka CLI and add the following content to the files:
      sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required \
username="**********" \
password="**********";        
sasl.mechanism=PLAIN

      Parameter description:

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

    • If SCRAM-SHA-512 is used, find the consumer.properties and producer.properties files in the /config directory of the Kafka CLI and add the following content to the files:
      sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required \
username="**********" \
password="**********";        
sasl.mechanism=SCRAM-SHA-512

      Parameter description:

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

  4. Modify the Kafka CLI configuration file based on the security protocol.

    • SASL_SSL: Find the consumer.properties and producer.properties files in the /config directory of the Kafka CLI and add the following content to the files:
      security.protocol=SASL_SSL
ssl.truststore.location={ssl_truststore_path}
ssl.truststore.password=dms@kafka
ssl.endpoint.identification.algorithm=

      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.
    • SASL_PLAINTEXT: Find the consumer.properties and producer.properties files in the /config directory of the Kafka CLI and add the following content to the files:
      security.protocol=SASL_PLAINTEXT

  5. Access the /bin directory of the Kafka CLI.

    In Windows, you need to access the /bin/windows directory.

  6. Run the following command to create messages:

    ./kafka-console-producer.sh --broker-list ${connection addr} --topic ${topic name} --producer.config ../config/producer.properties

    Parameter description:

    • {connection-address}: the address obtained in Prerequisites. For public access, use Address (Public Network, Ciphertext). For intra-VPC access, use Address (Private Network, Ciphertext).
    • {topic-name}: the name of the topic created for the Kafka instance. If automatic topic creation has enabled for the Kafka instance, set this parameter to the name of a created topic or a topic that has not been created.

    The following example uses connection addresses 10.xx.xx.45:9095,10.xx.xx.127:9095,10.xx.xx.103:9095.

    After running the preceding command, you can send a message to the Kafka instance by writing it and pressing Enter. Each line of content is sent as a message.

    [root@ecs-kafka bin]#./kafka-console-producer.sh --broker-list 10.xx.xx.45:9095,10.xx.xx.127:9095,10.xx.xx.103:9095  --topic topic-demo --producer.config ../config/producer.properties
>Hello
>DMS
>Kafka!
>^C[root@ecs-kafka bin]#

    To stop creating messages, press Ctrl+C to exit.

  7. Run the following command to retrieve messages:

    ./kafka-console-consumer.sh --bootstrap-server ${connection-address} --topic ${topic-name} --group ${consumer-group-name} --from-beginning  --consumer.config ../config/consumer.properties

    Parameter description:

    • {connection-address}: the address obtained in Prerequisites. For public access, use Address (Public Network, Ciphertext). For intra-VPC access, use Address (Private Network, Ciphertext).
    • {topic-name}: the name of the topic created for the Kafka instance.
    • {consumer-group-name}: the consumer group name set based on your service requirements. If a consumer group name has been specified in the configuration file, ensure that you use the same name in the command line. Otherwise, consumption may fail. If a consumer group name starts with a special character, such as an underscore (_) or a number sign (#), the monitoring data cannot be displayed.

    Example:

    [root@ecs-kafka bin]#  ./kafka-console-consumer.sh --bootstrap-server 10.xx.xx.45:9095,10.xx.xx.127:9095,10.xx.xx.103:9095 --topic topic-demo --group order-test --from-beginning --consumer.config ../config/consumer.properties
Hello
DMS
Kafka!
^CProcessed a total of 3 messages
[root@ecs-kafka bin]#

    To stop retrieving messages, press Ctrl+C to exit.

Parent topic: Connecting to an Instance