Kafka CLI tools overview - Step-by-Step Execution

Process Flow - Kafka CLI tools overview

Start Kafka CLI

↓

Choose Tool

↓

Producer

↓

Send Msg

↓

Show Output

↓

End

This flow shows how you start Kafka CLI, pick a tool (producer, consumer, admin), perform actions, and see results.

Execution Sample

Kafka

kafka-console-producer --topic test
kafka-console-consumer --topic test --from-beginning
kafka-topics --list

These commands send messages, read messages, and list topics using Kafka CLI tools.

Process Table

Step	Command	Action	Result/Output
1	kafka-console-producer --topic test	Start producer to send messages	Ready to accept input for topic 'test'
2	Type 'Hello Kafka'	Send message to topic	Message 'Hello Kafka' sent
3	kafka-console-consumer --topic test --from-beginning	Start consumer to read messages	Reads messages from beginning of 'test'
4	Consumer outputs message	Display received message	'Hello Kafka' displayed
5	kafka-topics --list	List all topics	Shows list including 'test'
6	Exit	Stop CLI tools	CLI session ends

💡 User ends session or stops CLI tools

Status Tracker

Variable	Start	After Step 2	After Step 4	Final
Message Input	empty	'Hello Kafka'	'Hello Kafka'	session ended
Topic List	unknown	includes 'test'	includes 'test'	session ended

Key Moments - 3 Insights

Why does the consumer show messages only after starting it?

Because the consumer reads messages from the topic when it starts, as shown in step 3 and 4 in the execution_table.

What happens if you send a message before starting the consumer?

The message is stored in the topic and will be read when the consumer starts, as the consumer reads from the beginning (step 3).

How do you know which topics exist?

Using the kafka-topics --list command (step 5) shows all topics including the one used.

Visual Quiz - 3 Questions

Look at the execution_table, what is the output after step 2?

A Message 'Hello Kafka' sent

B Ready to accept input

C 'Hello Kafka' displayed

D Shows list including 'test'

💡 Hint

Check the 'Result/Output' column for step 2 in execution_table

At which step does the consumer start reading messages?

A Step 1

B Step 5

C Step 3

D Step 6

💡 Hint

Look at the 'Action' column in execution_table for when consumer starts

If you run kafka-topics --list after sending messages, what changes in variable_tracker?

A Message Input changes

B Topic List includes 'test'

C Message Input becomes 'Hello Kafka'

D No change in Topic List

💡 Hint

Refer to 'Topic List' row in variable_tracker after step 5

Concept Snapshot

Kafka CLI tools let you interact with Kafka from the command line.
Use kafka-console-producer to send messages.
Use kafka-console-consumer to read messages.
Use kafka-topics to manage topics.
Start tools, perform actions, see output, then exit.

Full Transcript

This visual execution shows how Kafka CLI tools work step-by-step. First, you start the producer to send messages to a topic. Then, you start the consumer to read messages from that topic. You can also list topics using the admin tool. Each step shows the command, what it does, and the output you see. Variables like message input and topic list change as you send and read messages. Key moments explain why the consumer reads messages only after starting and how to check existing topics. The quiz tests your understanding of these steps and outputs.

Practice

1. Which Kafka CLI tool is used to create a new topic?

easy

A. kafka-topics.sh --create

B. kafka-console-producer.sh

C. kafka-console-consumer.sh

D. kafka-configs.sh

Solution

1. Step 1: Identify the tool for topic management

   The kafka-topics.sh tool is used to manage topics including creation, deletion, and listing.

2. Step 2: Confirm the create option usage

   Using --create with kafka-topics.sh creates a new topic.

3. Final Answer:

   kafka-topics.sh --create -> Option A

4. Quick Check:

   Topic creation = kafka-topics.sh --create [OK]

Hint: Topic creation always uses kafka-topics.sh with --create [OK]

Common Mistakes:

• Confusing producer or consumer tools for topic creation
• Using kafka-configs.sh which manages configs, not topics
• Omitting --create option

2. Which of the following is the correct syntax to start a Kafka console producer connecting to a server at localhost:9092?

easy

A. kafka-console-producer.sh --connect localhost:9092 --topic mytopic

B. kafka-console-producer.sh --broker-list localhost:9092 --topic mytopic

C. kafka-console-producer.sh --server localhost:9092 --topic mytopic

D. kafka-console-producer.sh --bootstrap-server localhost:9092 --topic mytopic

Solution

1. Step 1: Identify the correct option for specifying Kafka server

   Modern Kafka CLI tools use --bootstrap-server to specify the Kafka server address.

2. Step 2: Check the full command syntax

   The correct syntax includes kafka-console-producer.sh --bootstrap-server localhost:9092 --topic mytopic.

3. Final Answer:

   kafka-console-producer.sh --bootstrap-server localhost:9092 --topic mytopic -> Option D

4. Quick Check:

   Use --bootstrap-server for server address [OK]

Hint: Always use --bootstrap-server to specify Kafka server [OK]

Common Mistakes:

• Using deprecated --broker-list instead of --bootstrap-server
• Using incorrect flags like --server or --connect
• Omitting the --topic option

3. What will be the output of this command if the topic test-topic has 3 messages: kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test-topic --from-beginning --max-messages 2?

medium

A. It will print all 3 messages from test-topic and then exit.

B. It will print the first 2 messages from test-topic and then exit.

C. It will print no messages because --max-messages is ignored.

D. It will print only the last message from test-topic.

Solution

1. Step 1: Understand the --max-messages option

   The --max-messages 2 option limits the consumer to read only 2 messages before exiting.

2. Step 2: Analyze the command behavior

   The command reads from the beginning and stops after printing 2 messages, even though the topic has 3 messages.

3. Final Answer:

   It will print the first 2 messages from test-topic and then exit. -> Option B

4. Quick Check:

   --max-messages limits output count [OK]

Hint: --max-messages limits how many messages are consumed [OK]

Common Mistakes:

• Assuming all messages will be printed ignoring --max-messages
• Thinking --max-messages prints last messages only
• Confusing --from-beginning with consuming only latest messages

4. You run this command but get an error: kafka-console-producer.sh --topic mytopic. What is missing?

medium

A. The --bootstrap-server option specifying the Kafka server address.

B. The --create option to create the topic.

C. The --from-beginning option to read messages.

D. The --max-messages option to limit output.

Solution

1. Step 1: Identify required options for kafka-console-producer.sh

   The producer needs to know which Kafka server to connect to, specified by --bootstrap-server.

2. Step 2: Check the given command

   The command lacks --bootstrap-server, so it cannot connect and throws an error.

3. Final Answer:

   The --bootstrap-server option specifying the Kafka server address. -> Option A

4. Quick Check:

   Producer needs --bootstrap-server to connect [OK]

Hint: Always include --bootstrap-server to avoid connection errors [OK]

Common Mistakes:

• Assuming topic creation is automatic without --create
• Confusing producer options with consumer options
• Adding irrelevant options like --from-beginning for producer

5. You want to list all topics on a Kafka server at localhost:9092. Which command correctly lists the topics?

hard

A. kafka-console-producer.sh --list --bootstrap-server localhost:9092

B. kafka-console-consumer.sh --list --bootstrap-server localhost:9092

C. kafka-topics.sh --list --bootstrap-server localhost:9092

D. kafka-configs.sh --list --bootstrap-server localhost:9092

Solution

1. Step 1: Identify the tool for listing topics

   The kafka-topics.sh tool manages topics and supports the --list option to show all topics.

2. Step 2: Confirm the correct command syntax

   Using --bootstrap-server localhost:9092 specifies the Kafka server to connect to.

3. Final Answer:

   kafka-topics.sh --list --bootstrap-server localhost:9092 -> Option C

4. Quick Check:

   List topics with kafka-topics.sh --list [OK]

Hint: Use kafka-topics.sh with --list to see all topics [OK]

Common Mistakes:

• Using consumer or producer tools to list topics
• Omitting --bootstrap-server causing connection failure
• Using kafka-configs.sh which lists configs, not topics