NiFi in docker container fails to talk to kafka: TimoutException, kafkacat ist working just fine - apache-kafka

Question

I have set up NiFi (1.11.4) & Kafka(2.5) via docker (docker-compose file below, actual NiFi flow definition https://github.com/geoHeil/streaming-reference).
When trying to follow up on basic getting started tutorials (such as https://towardsdatascience.com/big-data-managing-the-flow-of-data-with-apache-nifi-and-apache-kafka-af674cd8f926) which combine processors such as:
generate flowfile (CSV)
update attribute
PublishKafka2.0
I run into issues of timeoutException:
nifi_1 | 2020-06-10 11:15:47,311 ERROR [kafka-producer-network-thread | producer-2] o.a.n.p.k.pubsub.PublishKafkaRecord_2_0 PublishKafkaRecord_2_0[id=959f0e64-0172-1000-0000-0000650181a4] Failed to send StandardFlowFileRecord[uuid=944464e4-94ea-48dc-89fa-d19c34f163e7,claim=StandardContentClaim [resourceClaim=StandardResourceClaim[id=1591771086044-1, container=default, section=1], offset=227962, length=422],offset=0,name=c8dd1dd2-0ffe-4875-9d45-902ea331c210,size=422] to Kafka: org.apache.kafka.common.errors.TimeoutException: Expiring 64 record(s) for test-0: 30029 ms has passed since batch creation plus linger time
nifi_1 | org.apache.kafka.common.errors.TimeoutException: Expiring 64 record(s) for test-0: 30029 ms has passed since batch creation plus linger time
nifi_1 | 2020-06-10 11:15:47,311 ERROR [kafka-producer-network-thread | producer-2] o.a.n.p.k.pubsub.PublishKafkaRecord_2_0 PublishKafkaRecord_2_0[id=959f0e64-0172-1000-0000-0000650181a4] Failed to send StandardFlowFileRecord[uuid=944464e4-94ea-48dc-89fa-d19c34f163e7,claim=StandardContentClaim [resourceClaim=StandardResourceClaim[id=1591771086044-1, container=default, section=1], offset=227962, length=422],offset=0,name=c8dd1dd2-0ffe-4875-9d45-902ea331c210,size=422] to Kafka: org.apache.kafka.common.errors.TimeoutException: Expiring 64 record(s) for test-0: 30029 ms has passed since batch creation plus linger time
nifi_1 | org.apache.kafka.common.errors.TimeoutException: Expiring 64 record(s) for test-0: 30029 ms has passed since batch creation plus linger time
However, a:
kafkacat -C -b localhost:9092 -t test #starts listener
kafkacat -P -b localhost:9092 -t test #starts producer
pipes events just fine through the kafka instance.
The docker-compose file looks like:
version: "3"
services:
nifi:
image: apache/nifi:1.11.4
ports:
- 8080:8080 # Unsecured HTTP Web Port
environment:
- NIFI_WEB_HTTP_PORT=8080
- NIFI_CLUSTER_IS_NODE=true
- NIFI_CLUSTER_NODE_PROTOCOL_PORT=8082
- NIFI_ZK_CONNECT_STRING=zookeeper:2181
- NIFI_ELECTION_MAX_WAIT=1 min
links:
- broker
- zookeeper
volumes:
- ./for_nifi/conf:/opt/nifi/nifi-current/conf
zookeeper: #https://github.com/confluentinc/cp-all-in-one/blob/5.5.0-post/cp-all-in-one/docker-compose.yml#L5
image: confluentinc/cp-zookeeper:5.5.0
hostname: zookeeper
container_name: zookeeper
ports:
- "2181:2181"
environment:
ZOOKEEPER_CLIENT_PORT: 2181
ZOOKEEPER_TICK_TIME: 2000
broker:
image: confluentinc/cp-kafka:5.5.0
hostname: broker
container_name: broker
depends_on:
- zookeeper
ports:
- "29092:29092"
- "9092:9092"
environment:
KAFKA_BROKER_ID: 1
KAFKA_ZOOKEEPER_CONNECT: 'zookeeper:2181'
KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT
KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://broker:29092,PLAINTEXT_HOST://localhost:9092
KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
KAFKA_INTER_BROKER_LISTENER_NAME: PLAINTEXT
KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 1
KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 1
KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS: 0

Answer 1

You're using the wrong port to connect to the broker. By connecting to 9092 you connect to the listener that advertises localhost:9092 to the client for subsequent connections. That's why it works when you use kafkacat from your local machine (because 9092 is exposed to your local machine)
If you use broker:29092 then the broker will give the client the correct address for the connection (i.e. broker:29092).
To understand more about advertised listeners see this blog