# Scaling K2K

{% hint style="warning" %}
To execute K2K, you must agree to the EULA and secure a free license. 

Accept the EULA by setting `license.acceptEula` to `true` .
{% endhint %}

Effortlessly scale K2K by developing new applications with a standardized replication pipeline. This enhances your ability to manage increased workloads, elevate performance, and maximize throughput as partitions are seamlessly distributed across instances.

## Requirements

This tutorial assumes the following files exist (See [run-a-quick-example](https://docs.lenses.io/latest/k2k/1.0/tutorial/run-a-quick-example "mention") for more details):

{% tabs %}
{% tab title="k2k-pipeline.yml" %}

```yaml
name: "my-first-replication"
features:
  autoCreateControlTopics: enabled
  autoCreateTopics: enabled
source:
  kafka:
    common:
      "bootstrap.servers": "kafka-source:9092"
    consumer:
      "group.id": "k2k.my-first-k2k"
target:
  kafka:
    common:
      "bootstrap.servers": "kafka-target:9092"
replication:
  - source:
      topic: ".*"
  - sink:
      topic: source
      partition: source
```

{% endtab %}

{% tab title="docker-compose.yml" %}

```yaml
services:
  k2k:
    image: "lensesio/k2k:0.5.0"
    volumes:
      - ".:/pipelines"
    environment:
      OTEL_SERVICE_NAME: "k2k"
      OTEL_METRICS_EXPORTER: none
      OTEL_TRACES_EXPORTER: none
      OTEL_LOGS_EXPORTER: none
      #LENSES_K2K_ACCEPT_EULA: true
    command:
      - k2k
      - start
      - -f
      - /pipelines/k2k-pipeline.yml
      - -t
  kafka-source:
    image: "apache/kafka:3.8.0"
    environment:
      KAFKA_NODE_ID: 1
      KAFKA_PROCESS_ROLES: broker,controller
      KAFKA_LISTENERS: INTERNAL://:9092,EXTERNAL://:9094,CONTROLLER://:9093
      KAFKA_ADVERTISED_LISTENERS: INTERNAL://kafka-source:9092,EXTERNAL://127.0.0.1:9094
      KAFKA_INTER_BROKER_LISTENER_NAME: INTERNAL
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: CONTROLLER:PLAINTEXT,INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT
      KAFKA_CONTROLLER_LISTENER_NAMES: CONTROLLER
      KAFKA_CONTROLLER_QUORUM_VOTERS: 1@localhost:9093
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 1
      KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 1
      KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS: 0
      KAFKA_NUM_PARTITIONS: 3
    ports:
      - "9094:9094"
  kafka-target:
    image: "apache/kafka:3.8.0"
    environment:
      KAFKA_NODE_ID: 1
      KAFKA_PROCESS_ROLES: broker,controller
      KAFKA_LISTENERS: INTERNAL://:9092,EXTERNAL://:9099,CONTROLLER://:9093
      KAFKA_ADVERTISED_LISTENERS: INTERNAL://kafka-target:9092,EXTERNAL://127.0.0.1:9099
      KAFKA_INTER_BROKER_LISTENER_NAME: INTERNAL
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: CONTROLLER:PLAINTEXT,INTERNAL:PLAINTEXT,EXTERNAL:PLAINTEXT
      KAFKA_CONTROLLER_LISTENER_NAMES: CONTROLLER
      KAFKA_CONTROLLER_QUORUM_VOTERS: 1@localhost:9093
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 1
      KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 1
      KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS: 0
      KAFKA_NUM_PARTITIONS: 3
    ports:
      - 9099:9099
```

{% endtab %}
{% endtabs %}

To ensure a clean start, execute this command to reset any prior configurations from earlier tutorials.

```bash
docker compose down
```

{% stepper %}
{% step %}

## Starting the Kafka clusters

Use the following command to run the K2K replicator app:

<pre class="language-bash"><code class="lang-bash"><strong>#start k2k
</strong>docker compose up k2k
</code></pre>

{% endstep %}

{% step %}

## Creating topics and data

Run the following commands to create these topics: user-topic, transaction-topic, transfers-eu and transfers-us:

```bash
#create topic user-topic
docker compose exec kafka-source \
      ./opt/kafka/bin/kafka-topics.sh \
      --create \
      --topic user-topic \
      --partitions 5 \
      --bootstrap-server 127.0.0.1:9092 
#create topic transaction-topic
docker compose exec kafka-source \
      ./opt/kafka/bin/kafka-topics.sh \
      --create \
      --topic transaction-topic \
      --partitions 5 \
      --bootstrap-server 127.0.0.1:9092
#create topic transfers-eu      
docker compose exec kafka-source \
      ./opt/kafka/bin/kafka-topics.sh \
      --create \
      --topic transfers-eu \
      --partitions 5 \
      --bootstrap-server 127.0.0.1:9092 
      
#create topic transfers-us
docker compose exec kafka-source \
      ./opt/kafka/bin/kafka-topics.sh \
      --create \
      --topic transfers-us \
      --partitions 5 \
      --bootstrap-server 127.0.0.1:9092 
```

To insert test data, execute the following commands:

<pre class="language-bash"><code class="lang-bash"><strong>write some data to user-topic
</strong><strong>docker-compose exec kafka-source \
</strong>    ./opt/kafka/bin/kafka-producer-perf-test.sh \
    --topic user-topic \
    --num-records 100 \
    --record-size 20 \
    --throughput -1 \
    --producer-props bootstrap.servers=localhost:9092

#write some data to transaction-topic    
docker-compose exec kafka-source \
    ./opt/kafka/bin/kafka-producer-perf-test.sh \
    --topic transaction-topic \
    --num-records 100 \
    --record-size 20 \
    --throughput -1 \
    --producer-props bootstrap.servers=localhost:9092
    
#write some data to transfers-eu    
docker-compose exec kafka-source \
    ./opt/kafka/bin/kafka-producer-perf-test.sh \
    --topic transfer-eu \
    --num-records 100 \
    --record-size 20 \
    --throughput -1 \
    --producer-props bootstrap.servers=localhost:9092


#write some data to transfers-us    
docker-compose exec kafka-source \
    ./opt/kafka/bin/kafka-producer-perf-test.sh \
    --topic transfers-us \
    --num-records 100 \
    --record-size 20 \
    --throughput -1 \
    --producer-props bootstrap.servers=localhost:9092
</code></pre>

{% endstep %}

{% step %}

## Run and Scale

```bash
#Start 5 K2K instances
docker compose up -d k2k --scale k2k=5
```

The replication pipeline is now distributed across five different instances.
{% endstep %}
{% endstepper %}