Description

Kafka is a high-performance, scalable, distributed messaging system.
This charm provides version 0.10.1 of the Kafka application from Apache Bigtop.

Overview

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 0.10.1 of the Kafka component from
Apache Bigtop.

Deploying

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.

Using

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.: 10.0.3.221:2181).

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

Verifying

Status

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>

Scaling

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'
kafka-0
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=10.0.2.0/24

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 0.0.0.0 to network_interface.

juju config kafka network_interface=0.0.0.0

Issues

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

https://issues.apache.org/jira/secure/CreateIssue!default.jspa

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

Resources

Configuration

network_interface
(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.
bigtop_version
(string) Apache Bigtop release version. The default, '1.2.1' will use the current GA release for all hiera data, puppet recipes, and installable packages. Set this to 'master' to use the latest upstream bits.
1.2.1
cuda-version
(string) The cuda-repo package version to install.
8.0.61-1
install-cuda
(boolean) Install the CUDA binaries if capable hardware is present. This option is False by default, as not all applications support GPU acceleration.