Can there be 2 Debezium connector running in one Kafka cluster?

From Debezium official page, there's this picture showing that multiple Debezium connector can connect to the same Kafka.

So I have 2 databases, 2 Debeziums, 1 Kafka running in docker-compose, but it seems like only 1 debezium sent update to kafka (watch from kafdrop).

Here's my docker-compose file:<br>

version: '3.6'
services:
hero_db:
image: postgres:14
restart: always
environment:
POSTGRES_PASSWORD: postgrespassword
ports:
- '5432:5432'
expose:
- '5432'
command: [ "postgres", "-c", "wal_level=logical" ]
volumes:
- hero_db_data:/var/lib/postgresql/data
villian_db:
image: postgres:14
restart: always
environment:
POSTGRES_PASSWORD: postgrespassword
ports:
- '2345:2345'
expose:
- '2345'
command: [ "postgres", "-c", "wal_level=logical" ]
volumes:
- villian_db_data:/var/lib/postgresql/data
zookeeper:
image: confluentinc/cp-zookeeper:latest
environment:
ZOOKEEPER_CLIENT_PORT: 2181
ZOOKEEPER_TICK_TIME: 2000
ports:
- 22181:2181
kafka:
image: confluentinc/cp-kafka:5.3.1
ports:
- 29092:29092
environment:
KAFKA_BROKER_ID: 1
KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:9092,PLAINTEXT_HOST://localhost:29092
KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT
KAFKA_INTER_BROKER_LISTENER_NAME: PLAINTEXT
KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
depends_on:
- zookeeper
kafdrop:
image: obsidiandynamics/kafdrop
container_name: kafdrop
ports:
- "9000:9000"
environment:
KAFKA_BROKERCONNECT: "kafka:9092"
JVM_OPTS: "-Xms16M -Xmx48M -Xss180K -XX:-TieredCompilation -XX:+UseStringDeduplication -noverify"
depends_on:
- kafka
hero_debezium:
image: debezium/connect:1.9
ports:
- 8083:8083
expose:
- '8083'
environment:
CONFIG_STORAGE_TOPIC: hero_configs
OFFSET_STORAGE_TOPIC: hero_offsets
STATUS_STORAGE_TOPIC: hero_statuses
BOOTSTRAP_SERVERS: kafka:9092
depends_on: [ zookeeper, kafka, hero_db ]
villian_debezium:
image: debezium/connect:1.9
ports:
- 8084:8083
expose:
- '8084'
environment:
CONFIG_STORAGE_TOPIC: villian_configs
OFFSET_STORAGE_TOPIC: villian_offsets
STATUS_STORAGE_TOPIC: villian_statuses
BOOTSTRAP_SERVERS: kafka:9092
depends_on: [ zookeeper, kafka, villian_db ]
volumes:
hero_db_data:
villian_db_data:

Here's a debezium config file in json of hero_dbz and villian_dbz:<br>
hero_dbz.json<br>

{
"name": "hero-postgresql-connector",
"config": {
"connector.class": "io.debezium.connector.postgresql.PostgresConnector",
"plugin.name": "pgoutput",
"database.hostname": "hero_db",
"database.port": "5432",
"database.user": "postgres",
"database.password": "postgrespassword",
"database.dbname": "postgres",
"database.server.name": "hero_server",
"table.include.list": "public.heroes",
"table.whitelist": "public.heroes",
"topic.prefix": "topic_heroes"
}
}

villian_dbz.json<br>

{
"name": "villian-postgresql-connector",
"config": {
"connector.class": "io.debezium.connector.postgresql.PostgresConnector",
"plugin.name": "pgoutput",
"database.hostname": "villian_db",
"database.port": "2345",
"database.user": "postgres",
"database.password": "postgrespassword",
"database.dbname": "postgres",
"database.server.name": "villian_server",
"table.include.list": "public.villians",
"table.whitelist": "public.villians",
"topic.prefix": "topic_villian"
}
}

I config both hero_dbz & villian_dbz with these command:<br>
curl -i -X POST -H "Accept:application/json" -H "Content-Type:application/json" 127.0.0.1:8083/connectors/ --data "@hero_dbz.json"<br>
curl -i -X POST -H "Accept:application/json" -H "Content-Type:application/json" 127.0.0.1:8084/connectors/ --data "@villian_dbz.json"

Here's a screen from Kafdrop showing only data from hero_db (hero_server.public.heroes) but nothing from villian_db.

Shouldn't be a problem running multiple kafka-connect servers. There might an issue in your configuration and setup. Perhaps look into to logs of the villian connector.

your internal port of villan db is wrong IMHO:

villian_db:
image: postgres:14
restart: always
environment:
POSTGRES_PASSWORD: postgrespassword
ports:
- '2345:5432'
expose:
- '2345'
command: [ "postgres", "-c", "wal_level=logical" ]
volumes:
- villian_db_data:/var/lib/postgresql/data

updates:

please add different GROUP_IDs env to the connect clusters. background:
> This environment variable is required when running the Kafka Connect service. Set this to an ID that uniquely identifies the Kafka Connect cluster the service and its workers belong to.

Something like GROUP_ID: 3 and GROUP_ID: 2 for the other. Your json should point to 5432, internal port of PostgresDB, so the .json files should point to 5432 (both)

And Your Zookeeper is wrongly configures, please fix it like that:

....
ports:
- 2181:2181

After I fixed my villians_db to run on port 2345. Then connect both of hero and villian debezium to Kafka via their JSON file.<br>
Inside the villian_dbz it keep showing this message :

2023-02-25 20:43:15 2023-02-25 13:43:15,210 INFO   ||  [Worker clientId=connect-1, groupId=1] Rebalance started   [org.apache.kafka.connect.runtime.distributed.WorkerCoordinator]
2023-02-25 20:43:15 2023-02-25 13:43:15,210 INFO   ||  [Worker clientId=connect-1, groupId=1] (Re-)joining group   [org.apache.kafka.connect.runtime.distributed.WorkerCoordinator]
2023-02-25 20:43:15 2023-02-25 13:43:15,211 INFO   ||  [Worker clientId=connect-1, groupId=1] Successfully joined group with generation Generation{generationId=6, memberId='connect-1-a2647c32-4c10-48be-b832-a38a37a11cd0', protocol='sessioned'}   [org.apache.kafka.connect.runtime.distributed.WorkerCoordinator]
2023-02-25 20:43:15 2023-02-25 13:43:15,211 INFO   ||  [Worker clientId=connect-1, groupId=1] Successfully synced group in generation Generation{generationId=6, memberId='connect-1-a2647c32-4c10-48be-b832-a38a37a11cd0', protocol='sessioned'}   [org.apache.kafka.connect.runtime.distributed.WorkerCoordinator]
2023-02-25 20:43:15 2023-02-25 13:43:15,211 INFO   ||  [Worker clientId=connect-1, groupId=1] Joined group at generation 6 with protocol version 2 and got assignment: Assignment{error=0, leader='connect-1-07842920-d640-4c15-ae17-ad4900077143', leaderUrl='http://172.19.0.8:8083/', offset=5, connectorIds=[hero-postgresql-connector], taskIds=[], revokedConnectorIds=[], revokedTaskIds=[], delay=0} with rebalance delay: 0   [org.apache.kafka.connect.runtime.distributed.DistributedHerder]
2023-02-25 20:43:15 2023-02-25 13:43:15,211 WARN   ||  [Worker clientId=connect-1, groupId=1] Catching up to assignment's config offset.   [org.apache.kafka.connect.runtime.distributed.DistributedHerder]
2023-02-25 20:43:15 2023-02-25 13:43:15,211 INFO   ||  [Worker clientId=connect-1, groupId=1] Current config state offset -1 is behind group assignment 5, reading to end of config log   [org.apache.kafka.connect.runtime.distributed.DistributedHerder]
2023-02-25 20:43:15 2023-02-25 13:43:15,212 INFO   ||  [Worker clientId=connect-1, groupId=1] Finished reading to end of log and updated config snapshot, new config log offset: -1   [org.apache.kafka.connect.runtime.distributed.DistributedHerder]
2023-02-25 20:43:15 2023-02-25 13:43:15,212 INFO   ||  [Worker clientId=connect-1, groupId=1] Current config state offset -1 does not match group assignment 5. Forcing rebalance.   [org.apache.kafka.connect.runtime.distributed.DistributedHerder]

This error does not appear if only one (either hero or villian) dbz connect to Kafka.