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Last active November 3, 2024 05:01
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Kafka Crash Course

Kafka

Video Link: Apache Kafka Crash Course | What is Kafka?

Prerequisite

Commands

  • Start Zookeper Container and expose PORT 2181.
docker run -p 2181:2181 zookeeper
  • Start Kafka Container, expose PORT 9092 and setup ENV variables.
docker run -p 9092:9092 \
-e KAFKA_ZOOKEEPER_CONNECT=<PRIVATE_IP>:2181 \
-e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://<PRIVATE_IP>:9092 \
-e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 \
confluentinc/cp-kafka

Code

client.js

const { Kafka } = require("kafkajs");

exports.kafka = new Kafka({
  clientId: "my-app",
  brokers: ["<PRIVATE_IP>:9092"],
});

admin.js

const { kafka } = require("./client");

async function init() {
  const admin = kafka.admin();
  console.log("Admin connecting...");
  admin.connect();
  console.log("Adming Connection Success...");

  console.log("Creating Topic [rider-updates]");
  await admin.createTopics({
    topics: [
      {
        topic: "rider-updates",
        numPartitions: 2,
      },
    ],
  });
  console.log("Topic Created Success [rider-updates]");

  console.log("Disconnecting Admin..");
  await admin.disconnect();
}

init();

producer.js

const { kafka } = require("./client");
const readline = require("readline");

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
});

async function init() {
  const producer = kafka.producer();

  console.log("Connecting Producer");
  await producer.connect();
  console.log("Producer Connected Successfully");

  rl.setPrompt("> ");
  rl.prompt();

  rl.on("line", async function (line) {
    const [riderName, location] = line.split(" ");
    await producer.send({
      topic: "rider-updates",
      messages: [
        {
          partition: location.toLowerCase() === "north" ? 0 : 1,
          key: "location-update",
          value: JSON.stringify({ name: riderName, location }),
        },
      ],
    });
  }).on("close", async () => {
    await producer.disconnect();
  });
}

init();

consumer.js

const { kafka } = require("./client");
const group = process.argv[2];

async function init() {
  const consumer = kafka.consumer({ groupId: group });
  await consumer.connect();

  await consumer.subscribe({ topics: ["rider-updates"], fromBeginning: true });

  await consumer.run({
    eachMessage: async ({ topic, partition, message, heartbeat, pause }) => {
      console.log(
        `${group}: [${topic}]: PART:${partition}:`,
        message.value.toString()
      );
    },
  });
}

init();

Running Locally

  • Run Multiple Consumers
node consumer.js <GROUP_NAME>
  • Create Producer
node producer.js
> tony south
> tony north
@DeepanshuGupta8990
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I am not able to generate and see SOUTH location. Its showing only NORTH

same issue

@DeepanshuGupta8990
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change the topic to something else like rider-status, I also had the same issue. i think it will keep the whatever code we deployed first so just change the topic. I hope it will work as intended.

this works .....but why......

@AnkitRanyal
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please make a video on the implementation of long polling and push

@basantojha1
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Very Helpful for Starters.. Thankyou.

@ChaitanyaBinmile
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@DeepanshuGupta8990 error related to only one partition being used
confirm this code snippet in your producer.js ,it works for me (mine had scope issue)
messages: [
{
partition: location.toLowerCase() === "north" ? 0 : 1,
key: "location-update",
value: JSON.stringify({ name: riderName, location }),
},
],

@Ankit-Yadav-21
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change the topic to something else like rider-status, I also had the same issue. i think it will keep the whatever code we deployed first so just change the topic. I hope it will work as intended.

This worked for me.

@Yash3456
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I am not able to generate and see SOUTH location. Its showing only NORTH

I also had this same issue, what worked for me is

* in admin.js file, update the topic name

* run admin.js again

* run producer and consumer again it worked for me

It worked for me as well

@Yash3456
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It worked well, Admin server need to be updated with new topic name else it won;t work

@crest-harikrushn
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Getting Error while running command : INFO SASL config status: Will not attempt to authenticate using SASL (unknown error). sudo docker run -p 9092:9092 \ -e KAFKA_ZOOKEEPER_CONNECT=192.168.43.70:2181 \ -e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://192.168.43.70:9092 \ -e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 \ confluentinc/cp-kafka Please help me on this

Remove \ and use the complete command in one line

docker run -p 9092:9092 -e KAFKA_ZOOKEEPER_CONNECT=192.168.43.70:2181 -e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://192.168.43.70:9092 -e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 confluentinc/cp-kafka

This worked for me. Thanks 👍 😎

@bhumit070
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bhumit070 commented Mar 12, 2024

If anyone need docker compose file

version: "3"

services:
    zookeeper:
        image: zookeeper
        container_name: zookeeper
        ports:
            - "2181:2181"

    kafka:
        image: confluentinc/cp-kafka
        depends_on:
            - zookeeper
        ports:
            - "9092:9092"
        expose:
            - "29092"
        environment:
            KAFKA_ZOOKEEPER_CONNECT: "zookeeper:2181"
            KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT
            KAFKA_INTER_BROKER_LISTENER_NAME: PLAINTEXT
            KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:29092,PLAINTEXT_HOST://localhost:9092
            KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: "1"
            KAFKA_MIN_INSYNC_REPLICAS: "1"

    kafka-ui:
        container_name: kafka-ui
        image: provectuslabs/kafka-ui
        ports:
            - 8080:8080
        environment:
            DYNAMIC_CONFIG_ENABLED: true

Also if you are getting error that port received NaN then type URL like this localhost:9092 instead of http://localhost:9092

Edit: add kafka UI

@Sagar-Puniyani
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@bhumit070 good work for creating decompose file

@jalakpatoliya
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Unable to find image ':2181' locally i got this error

I guess you forgot to use zookeeper at the end of it?
This is full line: docker run -p 2181:2181 zookeeper

@jalakpatoliya
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jalakpatoliya commented Mar 20, 2024

@bhumit070

If anyone need docker compose file

version: '3'

services:
  zookeeper:
    image: zookeeper
    ports:
      - "2181:2181"

  kafka:
    image: confluentinc/cp-kafka
    depends_on:
      - zookeeper
    ports:
      - "9092:9092"
    environment:
      - KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1
      - KAFKA_ZOOKEEPER_CONNECT=zookeeper:2181
      - KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://localhost:9092

Also if you are getting error that port received NaN then type URL like this localhost:9092 instead of http://localhost:9092

This is working like a charm, Thanks bro 😊

@jalakpatoliya
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jalakpatoliya commented Mar 20, 2024

docker run -p 9092:9092 -e KAFKA_ZOOKEEPER_CONNECT=192.168.43.70:2181 -e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://192.168.43.70:9092 -e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 confluentinc/cp-kafka

I tried your solution still getting error, below is what I used:

sudo docker run -p 9092:9092 -e KAFKA_ZOOKEEPER_CONNECT=103.171.98.61:2181 -e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://103.171.98.61:9092 -e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 confluentinc/cp-kafka

I'm having linux mint, and used curl ifconfig to get the ip.

Error:

java.net.ConnectException: Connection refused
at java.base/sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at java.base/sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:777)
at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:344)
at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1289)
[2024-03-20 13:32:49,380] INFO Opening socket connection to server 103.171.98.61/103.171.98.61:2181. (org.apache.zookeeper.ClientCnxn)
[2024-03-20 13:32:49,381] INFO SASL config status: Will not attempt to authenticate using SASL (unknown error) (org.apache.zookeeper.ClientCnxn)
[2024-03-20 13:32:49,387] WARN Session 0x0 for server 103.171.98.61/103.171.98.61:2181, Closing socket connection. Attempting reconnect except it is a SessionExpiredException. (org.apache.zookeeper.ClientCnxn)

@A1996KASH
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A1996KASH commented Mar 22, 2024

I am not able to generate and see SOUTH location. Its showing only NORTH

I also had this same issue, what worked for me is

* in admin.js file, update the topic name

* run admin.js again

* run producer and consumer again it worked for me

It worked for me as well

It worked well, Admin server need to be updated with new topic name else it won;t work

Does anyone knows the reason?

@dr4g0n7ly
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I need to run the consumer and producer on different servers. Can someone let me know what changes I should implement to set that up?

@A1996KASH
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I need to run the consumer and producer on different servers. Can someone let me know what changes I should implement to set that up?

Yes. Simply run producer file onto a different server you will have to copy client.js also on to another server

@dr4g0n7ly
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I need to run the consumer and producer on different servers. Can someone let me know what changes I should implement to set that up?

Yes. Simply run producer file onto a different server you will have to copy client.js also on to another server

Thank you for replying but I suspect I will have issues with the docker files and with establishing a connection from the producer to the consumer. Should I be worried about that?

@A1996KASH
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I need to run the consumer and producer on different servers. Can someone let me know what changes I should implement to set that up?

Yes. Simply run producer file onto a different server you will have to copy client.js also on to another server

Thank you for replying but I suspect I will have issues with the docker files and with establishing a connection from the producer to the consumer. Should I be worried about that?

No. I don't think so. Try it and share the git repo I will check and try to help.

@arshupadhyay
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arshupadhyay commented Apr 5, 2024

I am getting rebalancing error for two consumers. Do someone know how to solve this.

@A1996KASH
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I am getting rebalancing error for two consumers. Do someone know how to solve this.

Please share more details with screenshot

https://github.com/A1996KASH/apache-kafka-nodejs
It worked fine for me

@Akshaymk360
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south location is not visible even if i change my topic name in admin.js

@Akshaymk360
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I am not able to generate and see SOUTH location. Its showing only NORTH

I also had this same issue, what worked for me is

  • in admin.js file, update the topic name
  • run admin.js again
  • run producer and consumer again it worked for me

its not working for me bro

@Akshaymk360
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change the topic to something else like rider-status, I also had the same issue. i think it will keep the whatever code we deployed first so just change the topic. I hope it will work as intended.

this works .....but why......

should we change this in producer.js and consumer.js as well? or only in admin?

@Axhat
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Axhat commented May 21, 2024

I am not able to generate and see SOUTH location. Its showing only NORTH

I also had this same issue, what worked for me is

  • in admin.js file, update the topic name
  • run admin.js again
  • run producer and consumer again it worked for me

Working now! Thanks, Why do you think this was the case?

@skarthik05
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skarthik05 commented Jul 30, 2024

I am not able to generate and see SOUTH location. Its showing only NORTH

I also had this same issue, what worked for me is

  • in admin.js file, update the topic name
  • run admin.js again
  • run producer and consumer again it worked for me

Working now! Thanks, Why do you think this was the case?

In general, the topic name should remain the same throughout Kafka

  1. At the moment of creation
  2. When the producer is being produced
  3. At the moment of consuming

@Axhat I hope this helps

@pranayaapmor
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pranayaapmor commented Aug 22, 2024

Instead of <PRIVATE_IP> i want to use localhost, but its not working,(changed in kafka container and client.js)
is there any solution for this?

@Sonu-Hansda
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Instead of <PRIVATE_IP> i want to use localhost, but its not working,(changed in kafka container and client.js) is there any solution for this?

When running Kafka in Docker, you can't use localhost or 127.0.0.1 as the value for KAFKA_ZOOKEEPER_CONNECT and KAFKA_ADVERTISED_LISTENERS. This is because localhost and 127.0.0.1 refer to the container's own loopback interface, not the host machine's IP address. So you have to use your own IPv4 address

@rohhann12
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rohhann12 commented Sep 7, 2024

Instead of <PRIVATE_IP> i want to use localhost, but its not working,(changed in kafka container and client.js) is there any solution for this?

When running Kafka in Docker, you can't use localhost or 127.0.0.1 as the value for KAFKA_ZOOKEEPER_CONNECT and KAFKA_ADVERTISED_LISTENERS. This is because localhost and 127.0.0.1 refer to the container's own loopback interface, not the host machine's IP address. So you have to use your own IPv4 address.

for this you can use -p and expose your machine 's ports

@abhishek1savaliya
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Thanks this is the best tutorial for Kafka and works fine.

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