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.
Kafka requires the Zookeeper distributed coordination service. Deploy and relate them as follows:
juju deploy apache-zookeeper zookeeper
juju deploy apache-kafka kafka
juju add-relation kafka zookeeper
Once deployed, we can 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 action do kafka/0 list-zks
juju action fetch <id> # <-- id from above command
We can create a Kafka topic with:
juju action do kafka/0 create-topic topic=<topic_name> \
partitions=<#> replication=<#>
juju action fetch <id> # <-- id from above command
We can list topics with:
juju action do kafka/0 list-topics
juju action fetch <id> # <-- id from above command
We can write to a topic with:
juju action do kafka/0 write-topic topic=<topic_name> data=<data>
juju action fetch <id> # <-- id from above command
We can read from a topic with:
juju action do kafka/0 read-topic topic=<topic_name> partition=<#>
juju action fetch <id> # <-- id from above command
And finally, we can delete a topic with:
juju action do kafka/0 delete-topic topic=<topic_name>
juju action fetch <id> # <-- id from above command
Kafka provides extended status reporting to indicate when it is ready:
juju status --format=tabular
This is particularly useful when combined with watch to track the on-going
progress of the deployment:
watch -n 0.5 juju status --format=tabular
The message for each unit will provide information about that unit's state.
Once they all indicate that they are ready, you can perform a "smoke test"
to verify that Kafka is working as expected using the built-in smoke-test
action:
juju action do kafka/0 smoke-test
After a few seconds or so, you can check the results of the smoke test:
juju action status
You will see status: completed if the smoke test was successful, or
status: failed if it was not. You can get more information on why it failed
via:
juju action fetch <action-id>
Creating a cluster with many brokers is as easy as adding more units to your Kafka service:
juju add-unit kafka
After adding additional brokers, you will be able to create topics with replication up to the number of kafka units.
To verify replication is working you can do the following:
juju add-unit kafka -n 2
juju action do kafka/0 create-topic topic=my-replicated-topic \
partitions=1 replication=2
Query for the description of the just created topic:
juju ssh kafka/0
kafka-topics.sh --describe --topic my-replicated-topic \
--zookeeper <zookeeperip>:2181
You should get a response 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
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.
This charm can be deployed in environments with limited network access. To deploy in this environment, you will need a local mirror to serve the packages and resources required by this charm.
You can setup a local mirror for apt packages using squid-deb-proxy. For instructions on configuring juju to use this, see the Juju Proxy Documentation.
In addition to apt packages, this charm requires a few binary resources
which are normally hosted on Launchpad. If access to Launchpad is not
available, the jujuresources library makes it easy to create a mirror
of these resources:
sudo pip install jujuresources
juju-resources fetch --all /path/to/resources.yaml -d /tmp/resources
juju-resources serve -d /tmp/resources
This will fetch all of the resources needed by this charm and serve them via a
simple HTTP server. The output from juju-resources serve will give you a
URL that you can set as the resources_mirror config option for this charm.
Setting this option will cause all resources required by this charm to be
downloaded from the configured URL.