So what do I set for advertised.listeners?

1. If you clients are on your private network, set either:

    - the internal private IP

    - the internal private DNS hotname

2. Your clients should be able to resolve the internal IP or hostname

3. If your clients are on a public network, set either:

    - The external public IP

    - The external public DNS hostname pointing to the public IP

4. Your clients must be able to resolve the public DNS

What if I use the public IP... But after a reboot Kafka public IP changed!

1. Assume the IP of your server has changed:

    - FROM 34.56.78.90 => TO 34.56.78.12

What if I use the public IP?

 1. Advertised hostname is the most important setting of Kafka

But what if I put localhost? It works on my machine!

 1. Advertised hostname is the most important setting of Kafka

Understanding communications between Client and with Kafka

1. Advertised listeners is the most important setting of Kafka

Can I connect from the outside? e.g. my computer?

1. Zookeeper:

    - If you used Elastic private IPs(like in the tutorial), YES - demo

    - If you used Elastic public IPs                           YES

2. Kafka   

    - If you used Elastic private IPs(like in this tutorial), NO - demo

    - If you used Elastic public IPs                            YES

Hands On: Testing the cluster

1. Creating topics with a replication factor of 3

2. Publishing data to the topics

3. Reading data from the topics

4. Observing the Kafka filesystem

5. Deleting a topic

#!/bin/bash

# we can create topics with replication-factor 3 now!
bin/kafka-topics.sh --zookeeper zookeeper1:2181,zookeeper2:2181,zookeeper3:2181/kafka --create --topic second_topic --replication-factor 3 --partitions 3

# we can publish data to Kafka using the bootstrap server list!
bin/kafka-console-producer.sh --broker-list kafka1:9092,kafka2:9092,kafka3:9092 --topic second_topic

# we can read data using any broker too!
bin/kafka-console-consumer.sh --bootstrap-server kafka1:9092,kafka2:9092,kafka3:9092 --topic second_topic --from-beginning

# we can create topics with replication-factor 3 now!
bin/kafka-topics.sh --zookeeper zookeeper1:2181,zookeeper2:2181,zookeeper3:2181/kafka --create --topic third_topic --replication-factor 3 --partitions 3

# let's list topics
bin/kafka-topics.sh --zookeeper zookeeper1:2181,zookeeper2:2181,zookeeper3:2181/kafka --list

# publish some data
bin/kafka-console-producer.sh --broker-list kafka1:9092,kafka2:9092,kafka3:9092 --topic third_topic

# let's delete that topic
bin/kafka-topics.sh --zookeeper zookeeper1:2181,zookeeper2:2181,zookeeper3:2181/kafka --delete --topic third_topic

# it should be deleted shortly:
bin/kafka-topics.sh --zookeeper zookeeper1:2181,zookeeper2:2181,zookeeper3:2181/kafka --list