Output written to disk file

[MrMickS]

I'm trying to use this module and have the following configuration:

<IfDefine KAFKA>
  LoadModule kafka_module modules/mod_kafka.so
</IfDefine>
<IfModule kafka_module>
# Kafka brokers: host[:port][,host[:port]] (DEFAULT: localhost:9092)
KafkaBrokers ${KAFKA_BROKER}

# Kafka config: optional
KafkaConf global reconnect.backoff.jitter.ms 1000
KafkaConf topic request.timeout.ms 10000

# Kafka output: kafka:topic[@partition] log
CustomLog kafka:${KAFKA_TOPIC} combined

# Kafka output: topic and partition from logfomat
## format : "kafka:topic[@partition]|..."
#LogFormat "kafka:test|%h %l %u %t \"%r\" .." kafka_log
#CustomLog kafka:- kafka_log
</IfModule>

I pass in a KAFKA_TOPIC of http_topic and the output is written to a file kafka:http_topic.

If I run with LogLevel debug I see no Kafka module messages.