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Kafka TelSol

About the Project

This project was implemented as part of the IT Infrastructure Design class at the ECE School of NTUA. It explores the synchronous and asynchronous communication capabilites of Apache Kafka in a microservices platform.

Linux Installation Instructions

1. Install Docker

  1. Select your server (i.e. Debian, Fedora, Ubuntu) from here.
  2. Follow the instructions on sections SET UP THE REPOSITORY and INSTALL DOCKER ENGINE.

2. Install maven for the java applications

3. Clone this repo

git clone https://github.com/AthinaKyriakou/kafka-telsol.git
cd kafka-telsol

Start Playing

Open a terminal into the kafka-telsol directory.

1. Start your containers with Docker Compose

  1. Run Docker Compose on a terminal. The first time it runs for long...
docker-compose up -d
  1. Make sure that everything is up and running
docker-compose ps
Container name Command State Ports
broker /etc/confluent/docker/run Up 0.0.0.0:9092->9092/tcp
kafka-connect bash -c cd /usr/share/conf ... Up (healthy) 0.0.0.0:8083->8083/tcp, 9092/tcp
kafkacat /bin/sh -c apk add jq; Up
wh ...
ksqldb /usr/bin/docker/run Up 0.0.0.0:8088->8088/tcp
mysql docker-entrypoint.sh mysqld Up 0.0.0.0:3306->3306/tcp, 33060/tcp
schema-registry /etc/confluent/docker/run Up 0.0.0.0:8081->8081/tcp
zookeeper /etc/confluent/docker/run Up 2181/tcp, 2888/tcp, 3888/tcp

2. Check the installation of the MySQL JDBC driver (optional)

a. Find the location of the JDBC plugin

docker-compose logs kafka-connect|grep kafka-connect-jdbc|more

Copy path: INFO Loading plugin from:

b. Get into the kafka-connect container and cd into the found path

docker exec -it kafka-connect bash
cd <path>
ls

Within this folder there needs to be the mysql-connector-java-8.0.23.jar of the JDBC driver.

3. Producer: Create Kafka topics and publish data

a. From the customized Java producerApp

Adapted from here.

Get in the producerApp folder:

cd producerApp

Compile the producerApp:

mvn clean compile package

Run the producerApp:

mvn exec:java -Dexec.mainClass=io.confluent.examples.clients.basicavro.KafkaProducerApplication

b. In a new terminal start ksqldb (to interface with Kafka)

In new terminal start ksqldb:

docker exec -it ksqldb ksql http://ksqldb:8088

Create the test01 topic using Apache Avro to manage the schema (alternative JSON)

CREATE STREAM TEST01 (COL1 INT, COL2 VARCHAR)
  WITH (KAFKA_TOPIC='test01', PARTITIONS=1, VALUE_FORMAT='AVRO');

Insert dummy data to test01 topic

INSERT INTO TEST01 (ROWKEY, COL1, COL2) VALUES ('X',1,'FOO');
INSERT INTO TEST01 (ROWKEY, COL1, COL2) VALUES ('Y',2,'BAR');

Show topics and print the data

SHOW TOPICS;
PRINT test01 FROM BEGINNING;

4. Consumer: Read data from Kafka topics

a. From the customized Java consumerApp

Get in the consumerApp folder:

cd consumerApp

Compile the consumerApp:

mvn clean compile package

Run the producerApp:

mvn exec:java -Dexec.mainClass=io.confluent.examples.clients.basicavro.KafkaConsumerApplication

5. Insert data from a topic to MySQL db

a. In a new terminal open MySQL as root, create a demo database and grant privileges to athina user (which is the MYSQL_USER=athina in the docker-compose.yml file)

docker exec -it mysql bash -c 'mysql -u root -p$MYSQL_ROOT_PASSWORD'
create database demo;
grant all on demo.* to 'athina'@'%';

To check that privileges were granted you can start MySQL as athina user

docker exec -it mysql bash -c 'mysql -u$MYSQL_USER -p$MYSQL_PASSWORD'

and run

use demo;
show grants;

b. Create the Sink JDBC MySQL connector using the REST interface of Kafka

In a new terminal:

curl -X PUT http://localhost:8083/connectors/sink-jdbc-mysql-01/config \
     -H "Content-Type: application/json" -d '{
    "connector.class": "io.confluent.connect.jdbc.JdbcSinkConnector",
    "connection.url": "jdbc:mysql://mysql:3306/demo",
    "topics": "insertion_db", "insertion_db_points",
    "key.converter": "org.apache.kafka.connect.storage.StringConverter",
    "connection.user": "athina",
    "connection.password": "athina",
    "auto.create": true,
    "auto.evolve": true,
    "insert.mode": "insert",
    "pk.mode": "record_key",
    "pk.fields": "MESSAGE_KEY"
}'

Here we insert data to the demo db from the test01 topic. Each topic will create its own table in the db.

c. Check that the Sink JDBC MySQL connector is working from the ksqldb terminal

show connectors;

6. Check the created topic table and the inserted data in MySQL

In a new terminal open MySQL:

docker exec -it mysql bash -c 'mysql -u root -p$MYSQL_ROOT_PASSWORD'

Use the created db, see the created table from the test01 topic the inserted data.

use demo;
select * from test01;

Keep publishing data to the test01 topic from the ksqldb. The data will appear in the test01 table of the demo database.

7. User Data Validator App

Get in the userDataValidatorApp folder:

cd userDataValidatorApp

When you run the userDataValidatorApp for the first time:

gradle wrapper

Compile the userDataValidatorApp:

./gradlew shadowJar

Run the userDataValidatorApp:

java -jar build/libs/kafka-user-data-validator-application-standalone-0.0.1.jar

For logs

Kafka Connect

docker logs -f kafka-connect

Terminal Hack

To keep track of what is happening, I usually have the following terminals open:

  • one open in the kafka-telsol folder
  • MySQL:
docker exec -it mysql bash -c 'mysql -u root -p$MYSQL_ROOT_PASSWORD'
  • ksqlDB:
docker exec -it ksqldb ksql http://ksqldb:8088
  • logs:
docker logs -f kafka-connect