in flume-kafka-channel/src/main/java/org/apache/flume/channel/kafka/KafkaChannel.java [216:233]
private void setProducerProps(Context ctx, String bootStrapServers) {
producerProps.clear();
producerProps.put(ProducerConfig.ACKS_CONFIG, DEFAULT_ACKS);
producerProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, DEFAULT_KEY_SERIALIZER);
producerProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, DEFAULT_VALUE_SERIAIZER);
// Defaults overridden based on config
producerProps.putAll(ctx.getSubProperties(KAFKA_PRODUCER_PREFIX));
producerProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootStrapServers);
// The default value of `ssl.endpoint.identification.algorithm`
// is changed to `https`, since kafka client 2.0+
// And because flume does not accept an empty string as property value,
// so we need to use an alternative custom property
// `ssl.disableTLSHostnameVerification` to check if enable fqdn check.
if (isSSLEnabled(producerProps) && "true".equalsIgnoreCase(producerProps.getProperty(SSL_DISABLE_FQDN_CHECK))) {
producerProps.put(SslConfigs.SSL_ENDPOINT_IDENTIFICATION_ALGORITHM_CONFIG, "");
}
KafkaSSLUtil.addGlobalSSLParameters(producerProps);
}