Create a test topic in Hermes using the Kafka client

Create a topic for sending and receiving test messages in the Hermes Kafka cluster.

Before you begin

• Secure your Kafka topics by generating a ServiceNow® instance-signed certificate and keystore. You must provide truststore and keystore details when you configure a producer to create a topic in Hermes. See Set up a secure connection to the Hermes Messaging Service.
• Download and install Apache Kafka. See Prepare your Apache Kafka client environment.

Role required: admin

About this task

The full Hermes Kafka topic name is composed of the following elements:

snc.<instance_name>.<namespace>.<app_id>.<topic_name>

where:

• <instance_name> is the name of your instance
• <namespace> is the namespace of the domain your Kafka topic belongs to (optional)
• <app_id> is your application ID

  The topic you create belongs to this application. Specify either of the following:

  • sn_logstoanalytics for Log Export Service topics
  • sn_streamconnect for Stream Connect topics
• <topic_name> is the unique name for your topic

Note:

The full topic name is case-sensitive and limited to 200 characters.

Procedure

1. Navigate to the config directory where you extracted Kafka.
   • For example, on Unix:

     cd /home/user/Software/kafka/config

   • For example, on Windows:

     cd C:\Software\kafka\config

2. Configure a producer.
   1. Open the producer.properties file.
   2. Configure the following SSL properties:

      security.protocol=SSL
      
      ssl.truststore.password=<truststore password>
      
      ssl.truststore.location=<path to truststore.p12>
      
      ssl.truststore.type=PKCS12
      
      ssl.keystore.password=<keystore password>
      
      ssl.keystore.location=<path to keystore.p12>
      
      ssl.keystore.type=PKCS12
      
      ssl.key.password=<keystore password>

      Replace the following placeholder variables:

      • <truststore password> with your truststore password
      • <path to truststore.p12> with the path to your truststore file
      • <keystore password> with your keystore password
      • <path to keystore.p12> with the path to your keystore file
   3. Save your changes in plain text.
3. Navigate to your Kafka directory.
4. Create a test topic by running the following command:
   • Unix:

     ./bin/kafka-topics.sh --create --topic snc.<instance_name>.<namespace>.sn_<app_id>.<topic_name> --command-config ./config/producer.properties --bootstrap-server <instance_name>.service-now.com:4000,<instance_name>.service-now.com:4001,<instance_name>.service-now.com:4002,<instance_name>.service-now.com:4003

   • Windows:

     bin\windows\kafka-topics.bat --create --topic snc.<instance_name>.<namespace>.sn_<app_id>.<topic_name> --command-config config\producer.properties --bootstrap-server <instance_name>.service-now.com:4000,<instance_name>.service-now.com:4001,<instance_name>.service-now.com:4002,<instance_name>.service-now.com:4003

   Replace the following placeholder variables:

   • <instance_name> with your instance name (case-sensitive)
   • <namespace> with the namespace of the domain your Kafka topic belongs to (optional)
   • <app_id> with the application ID (case-sensitive)
   • <topic_name> with the unique topic name you want to use (case-sensitive)

Result

A test topic is created in the Hermes Kafka cluster.

What to do next

Produce test messages to a Hermes topic using the Kafka client