Symptoms
The standard Kafka producer (kafka-console-producer.sh) is unable to send messages and fails with the following timeout error:
org.apache.kafka.common.errors.TimeoutException
Causes
This situation occurs if the producer is invoked without supplying the required security credentials. In this case, the producer fails with the following error:
Error when sending message to topic <topicname> with key: null, value: <n> bytes
Resolving the problem
Create a properties file with the following content, adding by uncommenting either the SCRAM or Mutual TLS authentication settings depending on how the external listener has been configured.
bootstrap.servers=<kafka_bootstrap_host_url>
# SCRAM Properties
#security.protocol=SASL_SSL
#sasl.mechanism=SCRAM-SHA-512
#sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required username="<username>" password="<password>";
# Mutual auth properties
#security.protocol=SSL
#ssl.keystore.location=<java_keystore_file_location>
#ssl.keystore.password=<java_keystore_password>
# TLS Properties
ssl.protocol=TLSv1.2
ssl.truststore.location=<java_truststore_file_location>
ssl.truststore.password=<java_truststore_password>
Replace the <kafka_bootstrap_host_url> with the address of the Kafka bootstrap host.
If you used SCRAM authentication for the external listener, replace <username> with the SCRAM user name and <password> with the SCRAM user’s password.
If you used Mutual TLS authentication for the external listener, replace <java_keystore_file_location> with the location of a key store containing the client certificate and <java_keystore_password> with the password for the key store.
Finally, replace <java_truststore_file_location> with the location of a trust store file containing the server certificate (for example, certs.jks), and <java_truststore_password> with the password for the trust store.
When running the kafka-console-producer.sh command, include the --producer.config <properties_file> option, replacing <properties_file> with the name of the property file and the path to it. For example:
kafka-console-producer.sh --broker-list <brokerIP>:<bootstrapPort> --topic <topic> --producer.config <properties_file>