bitnami/kafka repository overview

⁠Bitnami Secure Image for Apache Kafka

⁠What is Apache Kafka?

Overview of Apache Kafka⁠ Trademarks: This software listing is packaged by Bitnami. The respective trademarks mentioned in the offering are owned by the respective companies, and use of them does not imply any affiliation or endorsement.

⁠TL;DR

docker run --name kafka bitnami/kafka:latest

⁠Why use Bitnami Secure Images?

Those are hardened, minimal CVE images built and maintained by Bitnami. Bitnami Secure Images are based on the cloud-optimized, security-hardened enterprise OS Photon Linux⁠. Why choose BSI images?

• Hardened secure images of popular open source software with Near-Zero Vulnerabilities
• Vulnerability Triage & Prioritization with VEX Statements, KEV and EPSS Scores
• Compliance focus with FIPS, STIG, and air-gap options, including secure bill of materials (SBOM)
• Software supply chain provenance attestation through in-toto
• First class support for the internet’s favorite Helm charts

Each image comes with valuable security metadata. You can view the metadata in our public catalog here⁠. Note: Some data is only available with commercial subscriptions to BSI⁠.

If you are looking for our previous generation of images based on Debian Linux, please see the Bitnami Legacy registry⁠.

⁠How to deploy Apache Kafka in Kubernetes?

Deploying Bitnami applications as Helm Charts is the easiest way to get started with our applications on Kubernetes. Read more about the installation in the Bitnami Apache Kafka Chart GitHub repository⁠.

⁠Why use a non-root container?

Non-root container images add an extra layer of security and are generally recommended for production environments. However, because they run as a non-root user, privileged tasks are typically off-limits. Learn more about non-root containers in our docs⁠.

⁠Supported tags and respective Dockerfile links

Learn more about the Bitnami tagging policy and the difference between rolling tags and immutable tags in our documentation page⁠.

You can see the equivalence between the different tags by taking a look at the tags-info.yaml file present in the branch folder, i.e bitnami/ASSET/BRANCH/DISTRO/tags-info.yaml.

Subscribe to project updates by watching the bitnami/containers GitHub repo⁠.

⁠Get this image

The recommended way to get the Bitnami Apache Kafka Docker Image is to pull the prebuilt image from the Docker Hub Registry⁠.

docker pull bitnami/kafka:latest

To use a specific version, you can pull a versioned tag. You can view the list of available versions⁠ in the Docker Hub Registry.

docker pull bitnami/kafka:[TAG]

If you wish, you can also build the image yourself by cloning the repository, changing to the directory containing the Dockerfile and executing the docker build command. Remember to replace the APP, VERSION and OPERATING-SYSTEM path placeholders in the example command below with the correct values.

git clone https://github.com/bitnami/containers.git
cd bitnami/APP/VERSION/OPERATING-SYSTEM
docker build -t bitnami/APP:latest .

⁠Persisting your data

If you remove the container all your data and configurations will be lost, and the next time you run the image the database will be reinitialized. To avoid this loss of data, you should mount a volume that will persist even after the container is removed.

The image exposes a volume at /bitnami/kafka for the Apache Kafka data. For persistence you can mount a directory at this location from your host. If the mounted directory is empty, it will be initialized on the first run.

Using Docker Compose:

This requires a minor change to the docker-compose.yml⁠ file present in this repository:

kafka:
  ...
  volumes:
    - /path/to/kafka-persistence:/bitnami/kafka
  ...

⁠Connecting to other containers

Using Docker container networking⁠, an Apache Kafka server running inside a container can easily be accessed by your application containers.

Containers attached to the same network can communicate with each other using the container name as the hostname.

⁠Using the Command Line

In this example, we will create an Apache Kafka client instance that will connect to the server instance that is running on the same docker network as the client.

⁠Step 1: Create a network

docker network create app-tier --driver bridge

⁠Step 2: Launch the Apache Kafka server instance

Use the --network app-tier argument to the docker run command to attach the Apache Kafka container to the app-tier network.

docker run -d --name kafka-server --hostname kafka-server \
    --network app-tier \
    -e KAFKA_CFG_NODE_ID=0 \
    -e KAFKA_CFG_PROCESS_ROLES=controller,broker \
    -e KAFKA_CFG_LISTENERS=PLAINTEXT://:9092,CONTROLLER://:9093 \
    -e KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP=CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT \
    -e KAFKA_CFG_CONTROLLER_LISTENER_NAMES=CONTROLLER \
    bitnami/kafka:latest

⁠Step 3: Launch your Apache Kafka client instance

Finally we create a new container instance to launch the Apache Kafka client and connect to the server created in the previous step:

docker run -it --rm \
    --network app-tier \
    bitnami/kafka:latest kafka-topics.sh --list  --bootstrap-server kafka-server:9092

⁠Using a Docker Compose file

When not specified, Docker Compose automatically sets up a new network and attaches all deployed services to that network. However, we will explicitly define a new bridge network named app-tier. In this example we assume that you want to connect to the Apache Kafka server from your own custom application image which is identified in the following snippet by the service name myapp.

version: '2'

networks:
  app-tier:
    driver: bridge

services:
  kafka:
    image: bitnami/kafka:latest
    networks:
      - app-tier
    environment:
      - KAFKA_CFG_NODE_ID=0
      - KAFKA_CFG_PROCESS_ROLES=controller,broker
      - KAFKA_CFG_LISTENERS=PLAINTEXT://:9092,CONTROLLER://:9093
      - KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP=CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT
      - KAFKA_CFG_CONTROLLER_LISTENER_NAMES=CONTROLLER
  myapp:
    image: YOUR_APPLICATION_IMAGE
    networks:
      - app-tier

Launch the containers using:

docker-compose up -d

⁠Configuration

⁠Environment variables

⁠Customizable environment variables

⁠Read-only environment variables

Additionally, any environment variable beginning with KAFKA_CFG_ will be mapped to its corresponding Apache Kafka key. For example, use KAFKA_CFG_BACKGROUND_THREADS in order to set background.threads or KAFKA_CFG_AUTO_CREATE_TOPICS_ENABLE in order to configure auto.create.topics.enable.

docker run --name kafka -e KAFKA_CFG_PROCESS_ROLES ... -e KAFKA_CFG_AUTO_CREATE_TOPICS_ENABLE=true bitnami/kafka:latest

or by modifying the docker-compose.yml⁠ file present in this repository:

kafka:
  ...
  environment:
    - KAFKA_CFG_AUTO_CREATE_TOPICS_ENABLE=true
  ...

⁠Apache Kafka development setup example

To use Apache Kafka in a development setup, create the following docker-compose.yml file:

version: "3"
services:
  kafka:
    image: bitnami/kafka:latest
    ports:
      - 9092:9092
    environment:
      - KAFKA_CFG_NODE_ID=0
      - KAFKA_CFG_PROCESS_ROLES=controller,broker
      - KAFKA_CFG_LISTENERS=PLAINTEXT://:9092,CONTROLLER://:9093
      - KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP=CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT
      - KAFKA_CFG_CONTROLLER_LISTENER_NAMES=CONTROLLER

To deploy it, run the following command in the directory where the docker-compose.yml file is located:

docker-compose up -d

⁠Accessing Apache Kafka with internal and external clients

In order to use internal and external clients to access Apache Kafka brokers you need to configure one listener for each kind of client.

To do so, add the following environment variables to your docker-compose:

    environment:
      - KAFKA_CFG_NODE_ID=0
      - KAFKA_CFG_PROCESS_ROLES=controller,broker
+     - KAFKA_CFG_LISTENERS=PLAINTEXT://:9092,CONTROLLER://:9093,EXTERNAL://:9094
+     - KAFKA_CFG_ADVERTISED_LISTENERS=PLAINTEXT://kafka:9092,EXTERNAL://localhost:9094
+     - KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP=CONTROLLER:PLAINTEXT,EXTERNAL:PLAINTEXT,PLAINTEXT:PLAINTEXT
      - KAFKA_CFG_CONTROLLER_LISTENER_NAMES=CONTROLLER

And expose the external port:

(the internal, client one can still be used within the docker network)

    ports:
-     - 9092:9092
+     - 9094:9094

Note: To connect from an external machine, change localhost above to your host's external IP/hostname and include EXTERNAL://0.0.0.0:9094 in KAFKA_CFG_LISTENERS to allow for remote connections.

⁠Producer and consumer using external client

These clients, from the same host, will use localhost to connect to Apache Kafka.

kafka-console-producer.sh --producer.config /opt/bitnami/kafka/config/producer.properties --bootstrap-server 127.0.0.1:9094 --topic test
kafka-console-consumer.sh --consumer.config /opt/bitnami/kafka/config/consumer.properties --bootstrap-server 127.0.0.1:9094 --topic test --from-beginning

If running these commands from another machine, change the address accordingly.

⁠Producer and consumer using internal client

These clients, from other containers on the same Docker network, will use the kafka container service hostname to connect to Apache Kafka.

kafka-console-producer.sh --producer.config /opt/bitnami/kafka/config/producer.properties --bootstrap-server kafka:9092 --topic test
kafka-console-consumer.sh --consumer.config /opt/bitnami/kafka/config/consumer.properties --bootstrap-server kafka:9092 --topic test --from-beginning

Similarly, application code will need to use bootstrap.servers=kafka:9092

More info about Apache Kafka listeners can be found in this great article⁠

⁠Security

In order to configure authentication, you must configure the Apache Kafka listeners properly. Let's see an example to configure Apache Kafka with SASL_SSL authentication for communications with clients, and SASL authentication for controller-related communications.

The environment variables below should be defined to configure the listeners, and the SASL credentials for client communications:

KAFKA_CFG_LISTENERS=SASL_SSL://:9092,CONTROLLER://:9093
KAFKA_CFG_ADVERTISED_LISTENERS=SASL_SSL://localhost:9092
KAFKA_CLIENT_USERS=user
KAFKA_CLIENT_PASSWORDS=password
KAFKA_CLIENT_LISTENER_NAME=SASL_SSL
KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP=CONTROLLER:SASL_PLAINTEXT,SASL_SSL:SASL_SSL
KAFKA_CFG_SASL_MECHANISM_CONTROLLER_PROTOCOL=PLAIN
KAFKA_CONTROLLER_USER=controller_user
KAFKA_CONTROLLER_PASSWORD=controller_password

You must also use your own certificates for SSL. You can drop your Java Key Stores or PEM files into /opt/bitnami/kafka/config/certs. If the JKS or PEM certs are password protected (recommended), you will need to provide it to get access to the keystores:

KAFKA_CERTIFICATE_PASSWORD=myCertificatePassword

If the truststore is mounted in a different location than /opt/bitnami/kafka/config/certs/kafka.truststore.jks, /opt/bitnami/kafka/config/certs/kafka.truststore.pem, /bitnami/kafka/config/certs/kafka.truststore.jks or /bitnami/kafka/config/certs/kafka.truststore.pem, set the KAFKA_TLS_TRUSTSTORE_FILE variable.

The following script can help you with the creation of the JKS and certificates:

• kafka-generate-ssl.sh⁠

Keep in mind the following notes:

• When prompted to enter a password, use the same one for all.
• Set the Common Name or FQDN values to your Apache Kafka container hostname, e.g. kafka.example.com. After entering this value, when prompted "What is your first and last name?", enter this value as well.
  • As an alternative, you can disable host name verification setting the environment variable KAFKA_CFG_SSL_ENDPOINT_IDENTIFICATION_ALGORITHM to an empty string.
• When setting up a Apache Kafka Cluster (check the "Setting up an Apache Kafka Cluster") for more information), each Apache Kafka broker and logical client needs its own keystore. You will have to repeat the process for each of the brokers in the cluster.

The following docker-compose file is an example showing how to mount your JKS certificates protected by the password certificatePassword123. Additionally it is specifying the Apache Kafka container hostname and the credentials for the client user.

version: '2'

services:
  kafka:
    image: bitnami/kafka:latest
    hostname: kafka.example.com
    ports:
      - 9092
    environment:
      # KRaft
      - KAFKA_CFG_NODE_ID=0
      - KAFKA_CFG_PROCESS_ROLES=controller,broker
      # Listeners
      - KAFKA_CFG_LISTENERS=SASL_SSL://:9092,CONTROLLER://:9093
      - KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP=CONTROLLER:SASL_PLAINTEXT,SASL_SSL:SASL_SSL
      - KAFKA_CFG_ADVERTISED_LISTENERS=SASL_SSL://:9092
      - KAFKA_CFG_CONTROLLER_LISTENER_NAMES=CONTROLLER
      - KAFKA_CFG_INTER_BROKER_LISTENER_NAME=SASL_SSL
      - KAFKA_CLIENT_LISTENER_NAME=SASL_SSL # Remove this line if consumer/producer.properties are not required
      # SASL
      - KAFKA_CFG_SASL_MECHANISM_CONTROLLER_PROTOCOL=PLAIN
      - KAFKA_CFG_SASL_MECHANISM_INTER_BROKER_PROTOCOL=PLAIN
      - KAFKA_CONTROLLER_USER=controller_user
      - KAFKA_CONTROLLER_PASSWORD=controller_password
      - KAFKA_INTER_BROKER_USER=interbroker_user
      - KAFKA_INTER_BROKER_PASSWORD=interbroker_password
      - KAFKA_CLIENT_USERS=user
      - KAFKA_CLIENT_PASSWORDS=password
      # SSL
      - KAFKA_TLS_TYPE=JKS # or PEM
      - KAFKA_CERTIFICATE_PASSWORD=certificatePassword123
    volumes:
      # Both .jks and .pem files are supported
      # - ./kafka.keystore.pem:/opt/bitnami/kafka/config/certs/kafka.keystore.pem:ro
      # - ./kafka.keystore.key:/opt/bitnami/kafka/config/certs/kafka.keystore.key:ro
      # - ./kafka.truststore.pem:/opt/bitnami/kafka/config/certs/kafka.truststore.pem:ro
      - ./kafka.keystore.jks:/opt/bitnami/kafka/config/certs/kafka.keystore.jks:ro
      - ./kafka.

_Note: the README for this container is longer than the DockerHub length limit of 25000, so it has been trimmed. The full README can be found at https://github.com/bitnami/containers/blob/main/bitnami/kafka/README.md_