kafka #5

Supports: xenial


Kafka is a high-performance, scalable, distributed messaging system. This charm provides version of the Kafka application from Apache Bigtop.


Apache Kafka is an open-source message broker project developed by the Apache Software Foundation written in Scala. The project aims to provide a unified, high-throughput, low-latency platform for handling real-time data feeds. Learn more at kafka.apache.org.

This charm deploys version of the Kafka component from Apache Bigtop.


This charm requires Juju 2.0 or greater. If Juju is not yet set up, please follow the getting-started instructions prior to deploying this charm.

Kafka requires the Zookeeper distributed coordination service. Deploy and relate them as follows:

juju deploy kafka
juju deploy zookeeper
juju add-relation kafka zookeeper

Network-Restricted Environments

Charms can be deployed in environments with limited network access. To deploy in this environment, configure a Juju model with appropriate proxy and/or mirror options. See Configuring Models for more information.


Once deployed, there are a number of actions available in this charm.

List the zookeeper servers that our kafka brokers are connected to. The following will list <ip>:<port> information for each zookeeper unit in the environment (e.g.:

juju run-action kafka/0 list-zks
juju show-action-output <id>  # <-- id from above command

Create a Kafka topic with:

juju run-action kafka/0 create-topic topic=<topic_name> \
 partitions=<#> replication=<#>
juju show-action-output <id>  # <-- id from above command

List topics with:

juju run-action kafka/0 list-topics
juju show-action-output <id>  # <-- id from above command

Write to a topic with:

juju run-action kafka/0 write-topic topic=<topic_name> data=<data>
juju show-action-output <id>  # <-- id from above command

Read from a topic with:

juju run-action kafka/0 read-topic topic=<topic_name> partition=<#>
juju show-action-output <id>  # <-- id from above command



Apache Bigtop charms provide extended status reporting to indicate when they are ready:

juju status

This is particularly useful when combined with watch to track the on-going progress of the deployment:

watch -n 2 juju status

The message column will provide information about a given unit's state. This charm is ready for use once the status message indicates that it is ready.

Smoke Test

This charm provides a smoke-test action that can be used to verify the application is functioning as expected. The test will verify connectivity between Kafka and Zookeeper, and will test creation and listing of Kafka topics. Run the action as follows:

juju run-action slave/0 smoke-test

Watch the progress of the smoke test actions with:

watch -n 2 juju show-action-status

Eventually, the action should settle to status: completed. If it reports status: failed, the application is not working as expected. Get more information about a specific smoke test with:

juju show-action-output <action-id>


Expanding a cluster with many brokers is as easy as adding more Kafka units:

juju add-unit kafka

After adding additional brokers, topics may be created with replication up to the number of ready units. For example, if there are two ready units, create a replicated topic as follows:

juju run-action kafka/0 create-topic topic=my-replicated-topic \
    partitions=1 replication=2

Query the description of the recently created topic:

juju run --unit kafka/0 'kafka-topics.sh --describe \
    --topic my-replicated-topic --zookeeper <zookeeperip>:2181'

An expected response should be similar to:

Topic: my-replicated-topic PartitionCount:1 ReplicationFactor:2 Configs:
Topic: my-replicated-topic Partition: 0 Leader: 2 Replicas: 2,0 Isr: 2,0

Connecting External Clients

By default, this charm does not expose Kafka outside of the provider's network. To allow external clients to connect to Kafka, first expose the service:

juju expose kafka

Next, ensure the external client can resolve the short hostname of the kafka unit. A simple way to do this is to add an /etc/hosts entry on the external kafka client machine. Gather the needed info from juju:

user@juju-client$ juju run --unit kafka/0 'hostname -s'
user@juju-client$ juju status --format=yaml kafka/0 | grep public-address
public-address: 40.784.149.135

Update /etc/hosts on the external kafka client:

user@kafka-client$ echo "40.784.149.135 kafka-0" | sudo tee -a /etc/hosts

The external kafka client should now be able to access Kafka by using kafka-0:9092 as the broker.

Network Interfaces

In some network environments, kafka may need to be restricted to listen for incoming connections on a specific network interface (e.g.: for security reasons). To do so, configure kafka with either a network interface name or a CIDR range specifying a subnet. For example:

juju config kafka network_interface=eth0
juju config kafka network_interface=

Each kafka machine in the cluster will lookup the IP address of that network interface, or find the first network interface with an IP address in the specified subnet, and bind kafka to that address.

If a mistake is made and an invalid name for the network interface is configured, recover by re-configuring with the correct name and then run "juju resolved" on each unit:

juju config kafka network_interface=eth0
juju resolved kafka/0

To go back to listening on any network interface on the machine, simply pass to network_interface.

juju config kafka network_interface=


Apache Bigtop tracks issues using JIRA (Apache account required). File an issue for this charm at:


Ensure Bigtop is selected as the project. Typically, charm issues are filed in the deployment component with the latest stable release selected as the affected version. Any uncertain fields may be left blank.

Contact Information



(string) Apache Bigtop release version. The default, '1.2.1' will use the current GA release, Bigtop 1.2.1, for all hiera data, puppet recipes, and installable packages. Set this to 'master' to use the latest upstream bits.
(string) Version of the cuda-repo deb to install. Valid options can be found at: http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1604/x86_64
(boolean) Install the CUDA binaries if capable hardware is present (True by default). Set to False to disable CUDA installation regardless of capable hardware.
(string) Network interface to bind Kafka to. Defaults to accepting connections on all interfaces. Accepts either the name of an interface (e.g., 'eth0'), or a CIDR range. If the latter, we\'ll bind to the first interface that we find with an IP address in that range.