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Use the Kafka CLI terminal

Open the playground's terminal, run the standard Kafka tools against the simulated cluster, and change the cluster from the command line.

How-to guides 7 of 10

3 min read

Updated 13 October 2026

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The examples run in the free-play sandbox the playground opens with. The terminal command reference lists every tool, flag and builtin.

Steps

1. Open the terminal

Select the bar along the bottom of the playground, labelled user@broker-1:~ - kafka-cli, or press Ctrl+`. A drawer slides up over the lower part of the screen; drag its title bar to resize it, and double-click the title bar to put it back. On a phone, open ⋯ in the top bar and select kafka-cli ↗ under terminal: the terminal fills the screen, with a row of commands to tap and a RUN button.

Each time it opens, the terminal greets you with three lines, then the prompt:

kafka-cli - the Kafka CLI tools against the simulated cluster above. Reads render the frame on screen; changes animate on the canvas.
Start with `help`. You are on broker-1 - `ssh broker-2` moves you; the prompt shows the host (and its region on multi-region clusters).
Ctrl+` toggles this drawer, Esc returns focus to the canvas.
user@broker-1:/var/kafka-logs$

The greeting goes away when you run your first command. help lists the tools and builtins this release ships.

2. Run a read

Describe the sandbox’s topic:

kafka-topics --describe --topic orders
Topic: orders  PartitionCount: 3  ReplicationFactor: 3  Configs: min.insync.replicas=2,cleanup.policy=delete
	Partition: 0  Leader: 1  Replicas: 1,2,3  Isr: 1,2,3
	Partition: 1  Leader: 2  Replicas: 2,3,1  Isr: 2,3,1
	Partition: 2  Leader: 3  Replicas: 3,1,2  Isr: 3,1,2

Then the lag view of the group the canvas labels cg1. The tools know it by its id, c1, which kafka-consumer-groups --list prints:

kafka-consumer-groups --describe --group c1

The output has the real tool’s columns, GROUP, TOPIC, PARTITION, CURRENT-OFFSET, LOG-END-OFFSET, LAG, CONSUMER-ID, HOST and CLIENT-ID, one row per partition.

3. Change the cluster

Set a retention time on the topic:

kafka-configs --alter --entity-type topics --entity-name orders --add-config retention.ms=60000
Completed updating config for topic orders.

The change is recorded on the timeline like the matching button press, and travels in a shared link.

4. Use completion and history

Tab completes a tool, a flag or a live name, such as a topic, group, broker or config key, and ↑ and ↓ walk the history. The reference’s Keys table lists the other keys.

5. Close it

Press Ctrl+` again or select × in the title bar. Closing keeps the session: the output, the current directory and the history are there when you reopen it. Switching to another scenario starts a fresh session on the new cluster and keeps only the command history.

Check it worked

Describe the topic’s configuration:

kafka-configs --describe --entity-type topics --entity-name orders

The list of dynamic configs now includes retention.ms=60000.