Streaming pipeline

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Set up Kafka

If you don’t have Kafka already setup, here is a quick guide on how to run and use Kafka locally:

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Using Kafka locally

  1. In your terminal, clone this repository: git clone https://github.com/wurstmeister/kafka-docker.git.
  2. Change directory into that repository: cd kafka-docker.
  3. Edit the docker-compose.yml file to match this: 
    version: "2"
services:
  zookeeper:
    image: wurstmeister/zookeeper
    ports:
      - "2181:2181"
  kafka:
    build: .
    container_name: docker_kafka
    ports:
      - "9092:9092"
    expose:
      - "9093"
    environment:
      KAFKA_ADVERTISED_LISTENERS: INSIDE://kafka:9093,OUTSIDE://localhost:9092
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: INSIDE:PLAINTEXT,OUTSIDE:PLAINTEXT
      KAFKA_LISTENERS: INSIDE://0.0.0.0:9093,OUTSIDE://0.0.0.0:9092
      KAFKA_INTER_BROKER_LISTENER_NAME: INSIDE
      KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
  4. Start Docker: 
    docker-compose up
    If you encounter the error command not found: docker-compose, try running the following command instead: 
    docker compose up
  5. Start a terminal session in the running container: 
    docker exec -i -t -u root $(docker ps | grep docker_kafka | cut -d' ' -f1) /bin/bash
  6. Create a topic: 
    $KAFKA_HOME/bin/kafka-topics.sh --create --partitions 4 --bootstrap-server kafka:9092 --topic test
  7. List all available topics in Kafka instance: 
    $KAFKA_HOME/bin/kafka-topics.sh --bootstrap-server kafka:9092 --list
  8. Start a producer on topic named test: 
    $KAFKA_HOME/bin/kafka-console-producer.sh --broker-list kafka:9092 --topic=test
  9. Send messages to the topic named test by typing the following JSON strings in the terminal (Note that Kafka messages in Mage are assumed to be in JSON format): 
    >{ "hello": 1 }
>{ "this is a test": 1 }
>{ "test": 1 }
>{ "test": 2 }
>{ "test": 3 }
  10. Open another terminal and start a consumer on the topic named test:
$KAFKA_HOME/bin/kafka-console-consumer.sh --from-beginning --bootstrap-server kafka:9092 --topic=test
  1. The output should look something like this:
{ "hello": 1 }
{ "this is a test": 1 }
{ "test": 1 }
{ "test": 2 }
{ "test": 3 }
Original source of instructions.

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Build streaming pipeline

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Start Mage

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Using Kafka locally in a Docker container

Start Mage using Docker. Run the following command to run Docker in network mode: 
docker run -it -p 6789:6789 -v $(pwd):/home/src \
  --env AWS_ACCESS_KEY_ID=your_access_key_id \
  --env AWS_SECRET_ACCESS_KEY=your_secret_access_key \
  --env AWS_REGION=your_region \
  --network kafka-docker_default \
  mageai/mageai /app/run_app.sh  mage start default_repo
Change the environment variables argument depending on your cloud provider.
If the network named kafka-docker_default doesn’t exist, create a new network: 
docker network create -d bridge kafka-docker_default
Check that it exists: 
docker network ls
If you can’t connect to Kafka locally in a Docker container using Mage in a Docker container, do the following:
  1. Clone Mage: git clone https://github.com/mage-ai/mage-ai.git.
  2. Change directory into Mage: cd mage-ai.
  3. Edit the docker-compose.yml file to match this: 
    version: '3'
services:
  server:
    ... (original config)
    networks:
      - kafka
  app:
    ... (original config)
networks:
  kafka:
    name: kafka-docker_default
    external: true
  4. Run the following script in your terminal: ./scripts/dev.sh.
This will run Mage in development mode; which runs it in a Docker container using docker compose instead of docker run.

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Using Kafka without a Docker container

Start Mage using Docker. If you haven’t done this before, refer to the setup guide.

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Create a new pipeline

  1. Open Mage in your browser.
  2. Click + New pipeline, then select Streaming.
  3. Add a data loader block, select Kafka, and paste the following: 
    connector_type: kafka
bootstrap_server: "localhost:9092"
topic: test
consumer_group: unique_consumer_group
include_metadata: false
api_version: 0.10.2
batch_size: 100
    1. By default, the bootstrap_server is set to localhost:9092. If you’re running Mage in a docker container, the bootstrap_server should be kafka:9093.
    2. Messages are consumed from source in micro batch mode for better efficiency. The default batch size is 100. You can adjust the batch size in the source config.
  4. Add a transformer block and paste the following: 
    from typing import Dict, List

if 'transformer' not in globals():
    from mage_ai.data_preparation.decorators import transformer


@transformer
def transform(messages: List[Dict], *args, **kwargs):
    for msg in messages:
        print(msg)

    return messages
  5. Add a data exporter block, select OpenSearch and paste the following: 
    connector_type: opensearch
host: https://search-something-abcdefg123456.us-west-1.es.amazonaws.com/
index_name: python-test-index
    1. Change the host to match your OpenSearch domain’s endpoint.
    2. Change the index_name to match the index you want to export data into.

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Test pipeline

Open the streaming pipeline you just created, and in the right side panel near the bottom, click the button Execute pipeline to test the pipeline. You should see an output like this: 
[streaming_pipeline_test] [KafkaSource] Start initializing consumer.
[streaming_pipeline_test] [KafkaSource] Finish initializing consumer.
[streaming_pipeline_test] [KafkaSource] Test connection successfully.
[streaming_pipeline_test] [KafkaSource] Start consuming messages in batches.

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Publish messages using Python

  1. Open a terminal on your local workstation.
  2. Install kafka-python: 
    pip install kafka-python
  3. Open a Python shell and write the following code to publish messages: 
    from kafka import KafkaProducer
from random import random
import json


topic = 'test'
producer = KafkaProducer(
    bootstrap_servers='kafka:9093',
)


def publish_messages(limit):
    for i in range(limit):
        data = {
            'title': 'test_title',
            'director': 'Bennett Miller',
            'year': '2011',
            'rating': random(),
        }
        producer.send(topic, json.dumps(data).encode('utf-8'))

publish_messages(5)
Once you run the code snippet above, go back to your streaming pipeline in Mage and the output should look like this: 
[streaming_pipeline_test] Start initializing kafka consumer.
[streaming_pipeline_test] Finish initializing kafka consumer.
[streaming_pipeline_test] Start consuming messages from kafka.
[streaming_pipeline_test] [Kafka] Receive message 2:16: v=b'{"title": "test_title", "director": "Bennett Miller", "year": "2011", "rating": 0.7010424523477785}', time=1665618592.226788
[streaming_pipeline_test] [Kafka] Receive message 0:16: v=b'{"title": "test_title", "director": "Bennett Miller", "year": "2011", "rating": 0.7886308380991354}', time=1665618592.2268753
[streaming_pipeline_test] [Kafka] Receive message 0:17: v=b'{"title": "test_title", "director": "Bennett Miller", "year": "2011", "rating": 0.0673276352704153}', time=1665618592.2268832
[streaming_pipeline_test] [Kafka] Receive message 3:10: v=b'{"title": "test_title", "director": "Bennett Miller", "year": "2011", "rating": 0.37935417366095525}', time=1665618592.2268872
[streaming_pipeline_test] [Kafka] Receive message 3:11: v=b'{"title": "test_title", "director": "Bennett Miller", "year": "2011", "rating": 0.21110511524126563}', time=1665618592.2268918
[streaming_pipeline_test] {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.7010424523477785}
[streaming_pipeline_test] {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.7886308380991354}
[streaming_pipeline_test] {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.0673276352704153}
[streaming_pipeline_test] {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.37935417366095525}
[streaming_pipeline_test] {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.21110511524126563}
[streaming_pipeline_test] [Opensearch] Batch ingest data [{'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.7010424523477785}, {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.7886308380991354}, {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.0673276352704153}, {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.37935417366095525}, {'title': 'test_title', 'director': 'Bennett Miller', 'year': '2011', 'rating': 0.21110511524126563}], time=1665618592.2294626

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Consume messages using Python

If you want to programmatically consume messages from a Kafka topic, here is a code snippet: 
from kafka import KafkaConsumer
import time


topic = 'test'
consumer = KafkaConsumer(
    topic,
    group_id='test',
    bootstrap_servers='kafka:9093',
)

for message in consumer:
    print(f"{message.partition}:{message.offset}: v={message.value}, time={time.time()}")

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Run in production

  1. Create a trigger.
  2. Once trigger is created, click the Start trigger button at the top of the page to make the streaming pipeline active.