Variables & Secrets

Control parameters and secrets using the pipeline definition.

To execute K2K, you must agree to the EULA and secure a free license.

Accept the EULA by setting license.acceptEula to true .

K2K enables the inclusion of variables in the replication definition, allowing secrets to be injected at runtime without being embedded directly in the pipeline definition. See Variables and Secrets for more details.

This tutorial assumes the following files exist (See Setting up for more details):

k2k-pipeline.yml

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

docker-compose.yml

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

docker compose down

1

Define variables in the pipeline definition

The pipeline file includes two variables that will be substituted when the pipeline is loaded.

name: "my-first-replication"
features:
  autoCreateControlTopics: enabled
  autoCreateTopics: enabled
source:
  kafka:
    common:
      "bootstrap.servers": ${TARGET_BROKER_URL}
    consumer:
      "group.id": "k2k.my-first-k2k"
target:
  kafka:
    common:
      "bootstrap.servers": ${env:string:SOURCE_BROKER_URL}
replication:
  - source:
      topic: ".*"
  - sink:
      topic: source
      partition: source

2

Add the environment variables to the docker compose

services:
  k2k:
    image: "eu.gcr.io/k8-engine/k2k/k2k:0.0.10-alpha"
    volumes:
      - ".:/pipelines"
    environment:
      OTEL_SERVICE_NAME: "k2k"
      OTEL_METRICS_EXPORTER: none
      OTEL_TRACES_EXPORTER: none
      OTEL_LOGS_EXPORTER: none
      TARGET_BROKER_URL: "kafka-target:9092"
      SOURCE_BROKER_URL: "kafka-source:9092"
    command:
      - k2k
      - start
      - -f
      - /pipelines/k2k-pipeline.yml
      - -t
      - -g 
      - enabled
  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

3

Start Kafka Clusters

To start two local Kafka clusters, use this command:

#start two kafka instances
docker compose up -d kafka-source kafka-target

4

Run K2K

Use the following command to run the K2K replicator app:

#start k2k
docker compose up k2k