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What is merge cluster?

Conduktor Gateway's merge cluster brings all your Kafka clusters together into an instance for clients to access.

View the full demo in realtime​

You can either follow all the steps manually, or watch the recording

Review the docker compose environment​

As can be seen from docker-compose.yaml the demo environment consists of the following services:

  • gateway1
  • gateway2
  • kafka-client
  • kafka1
  • kafka2
  • kafka3
  • s1_kafka1
  • s1_kafka2
  • s1_kafka3
  • schema-registry
  • zookeeper
  • zookeeper_s1
cat docker-compose.yaml

Review the Gateway configuration​

Review the Gateway configuration

cat clusters.yaml

Starting the docker environment​

Start all your docker processes, wait for them to be up and ready, then run in background

  • --wait: Wait for services to be running|healthy. Implies detached mode.
  • --detach: Detached mode: Run containers in the background
docker compose up --detach --wait

Creating virtual cluster teamA​

Creating virtual cluster teamA on gateway gateway1 and reviewing the configuration file to access it

# Generate virtual cluster teamA with service account sa
token=$(curl \
    --request POST "http://localhost:8888/admin/vclusters/v1/vcluster/teamA/username/sa" \
    --header 'Content-Type: application/json' \
    --user 'admin:conduktor' \
    --silent \
    --data-raw '{"lifeTimeSeconds": 7776000}' | jq -r ".token")

# Create access file
echo  """
bootstrap.servers=localhost:6969
security.protocol=SASL_PLAINTEXT
sasl.mechanism=PLAIN
sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required username='sa' password='$token';
""" > teamA-sa.properties

# Review file
cat teamA-sa.properties

Create the topic 'cars' in main cluster​

Creating on kafka1:

  • Topic cars with partitions:1 and replication-factor:1
kafka-topics \
    --bootstrap-server localhost:19092,localhost:19093,localhost:19094 \
    --replication-factor 1 \
    --partitions 1 \
    --create --if-not-exists \
    --topic cars

Create the topic 'cars' in cluster1​

Creating on s1_kafka1:

  • Topic cars with partitions:1 and replication-factor:1
kafka-topics \
    --bootstrap-server localhost:29092,localhost:29093,localhost:29094 \
    --replication-factor 1 \
    --partitions 1 \
    --create --if-not-exists \
    --topic cars

Let's route the topic 'eu_cars', as seen by the client application, on to the 'cars' topic on the main (default) cluster​

curl \
  --silent \
  --request POST localhost:8888/internal/alias-topic/teamA/eu_cars \
  --user 'admin:conduktor' \
  --header 'Content-Type: application/json' \
  --data-raw '{
      "clusterId": "main",
      "physicalTopicName": "cars"
    }' | jq

Let's route the topic 'us_cars', as seen by the client application, on to the 'cars' topic on the second cluster (cluster1)​

curl \
  --silent \
  --request POST localhost:8888/internal/alias-topic/teamA/us_cars \
  --user 'admin:conduktor' \
  --header 'Content-Type: application/json' \
  --data-raw '{
      "clusterId": "cluster1",
      "physicalTopicName": "cars"
    }' | jq

Send into topic 'eu_cars'​

Producing 1 message in eu_cars in cluster teamA

Sending 1 event

{
  "name" : "eu_cars_record"
}

with

echo '{"name":"eu_cars_record"}' | \
    kafka-console-producer \
        --bootstrap-server localhost:6969 \
        --producer.config teamA-sa.properties \
        --topic eu_cars

Send into topic 'us_cars'​

Producing 1 message in us_cars in cluster teamA

Sending 1 event

{
  "name" : "us_cars_record"
}

with

echo '{"name":"us_cars_record"}' | \
    kafka-console-producer \
        --bootstrap-server localhost:6969 \
        --producer.config teamA-sa.properties \
        --topic us_cars

Consuming from eu_cars​

Consuming from eu_cars in cluster teamA

kafka-console-consumer \
    --bootstrap-server localhost:6969 \
    --consumer.config teamA-sa.properties \
    --topic eu_cars \
    --from-beginning \
    --timeout-ms 10000 | jq

returns 1 event

{
  "name" : "eu_cars_record"
}

Consuming from us_cars​

Consuming from us_cars in cluster teamA

kafka-console-consumer \
    --bootstrap-server localhost:6969 \
    --consumer.config teamA-sa.properties \
    --topic us_cars \
    --from-beginning \
    --timeout-ms 10000 | jq

returns 1 event

{
  "name" : "us_cars_record"
}

Verify eu_cars_record is not in main kafka​

Verify eu_cars_record is not in main kafka in cluster kafka1

kafka-console-consumer \
    --bootstrap-server localhost:19092,localhost:19093,localhost:19094 \
    --topic cars \
    --from-beginning \
    --timeout-ms 10000 | jq

returns 1 event

{
  "name" : "eu_cars_record"
}

Verify us_cars_record is not in cluster1 kafka​

Verify us_cars_record is not in cluster1 kafka in cluster s1_kafka1

kafka-console-consumer \
    --bootstrap-server localhost:29092,localhost:29093,localhost:29094 \
    --topic cars \
    --from-beginning \
    --timeout-ms 10000 | jq

returns 1 event

{
  "name" : "us_cars_record"
}

Tearing down the docker environment​

Remove all your docker processes and associated volumes

  • --volumes: Remove named volumes declared in the "volumes" section of the Compose file and anonymous volumes attached to containers.
docker compose down --volumes

Conclusion

Merge cluster is simple as it