Docker Image Configuration Reference for Confluent Platform

This topic describes how to configure the Docker images when starting Confluent Platform.

You can dynamically specify configuration values in the Confluent Platform Docker images with environment variables. You can use the Docker -e or --env flags to specify various configurations.

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Kafka configuration

The sections helps configure the following images that include Kafka:

cp-kafka - includes Kafka.
cp-server - includes role-based access control, self-balancing clusters, and more, in addition to Kafka.
confluent-local - includes Kafka and Confluent Rest Proxy . Defaults to running in KRaft mode.

Convert the properties file variables according to the following rules and use them as Docker environment variables:

Prefix Kafka component properties with KAFKA_. For example, metric.reporters is a Kafka property so should be converted to KAFKA_METRIC_REPORTERS.
Prefix Confluent component properties for cp-server with CONFLUENT_ for For example, confluent.metrics.reporter.bootstrap.servers is a Confluent Enterprise feature property, so, it should be converted to CONFLUENT_METRICS_REPORTER_BOOTSTRAP_SERVERS.
Convert to upper-case.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

Required Kafka configurations for KRaft mode

As of Confluent Platform 8.0, ZooKeeper has been removed. You must use KRaft mode for metadata management. For steps to migrate from ZooKeeper to KRaft, see Migrate from ZooKeeper to KRaft on Confluent Platform. For links to ZooKeeper topics in older versions of the documentation, see ZooKeeper Topic Guide.

Important

For more information about configuring KRaft in production, see KRaft Configuration for Confluent Platform.

KAFKA_PROCESS_ROLES: The role of this server (controller, broker or broker,controller).
KAFKA_NODE_ID: The unique identifier for this server.
KAFKA_CONTROLLER_QUORUM_VOTERS: A comma-separated list of quorum voters. Each controller is identified with their ID, host and port information in the format of {id}@{host}:{port}.
KAFKA_CONTROLLER_LISTENER_NAMES: A comma-separated list of the names of the listeners used by the controller. On a node with process.roles=broker, only the first listener in the list will be used by the broker. ZooKeeper-mode brokers should not set this value. For KRaft controllers in isolated or combined mode, the node will listen as a KRaft controller on all listeners that are listed for this property, and each must appear in the listeners property.

Optional `cp-server` setting

The license key is an optional setting for the Enterprise Kafka (cp-server) image for 30 days. For a complete list of Confluent Server configuration settings, see Kafka Configuration Reference for Confluent Platform.

KAFKA_CONFLUENT_LICENSE: The Enterprise Kafka license key. Without the license key, Confluent Server can be used for a 30-day trial period. Note that confluent is part of the property name and not the component name. For example, use KAFKA_CONFLUENT_LICENSE to specify the Kafka license.

Example configurations

The following examples show how to set environmental variables and run the Kafka images that Confluent provides. These examples:

Set the KAFKA_ADVERTISED_LISTENERS variable to localhost:29092. This makes Kafka accessible from outside of the container by advertising its location on the Docker host.
Set KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR to 1. This is required when you are running with a single-node cluster. If you have three or more nodes, you can use the default.
Each KRaft cluster must have a unique cluster ID assigned to its CLUSTER_ID variable. To learn how to use the kafka-storage tool to generate a unique ID, see Generate and format IDs.
These examples show KRaft combined mode, which is intended for local experimentation only and is not supported by Confluent. For production configuration, see Production Configuration Options.

`cp-kafka` example

The following examples show how to start cp-kafka in KRaft combined mode for brevity. Combined mode is designed for local experimentation and is not supported by Confluent. For production configuration recommendations, see Production Configuration Options.

Generate a random-uuid using the kafka-storage tool:

/bin/kafka-storage random-uuid

Assign the output to the CLUSTER_ID variable as shown in the following example:

docker run -d \
--name=kafka-kraft \
-h kafka-kraft \
-p 9101:9101 \
-e KAFKA_NODE_ID=1 \
-e KAFKA_LISTENER_SECURITY_PROTOCOL_MAP='CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT' \
-e KAFKA_ADVERTISED_LISTENERS='PLAINTEXT://kafka-kraft:29092,PLAINTEXT_HOST://localhost:9092' \
-e KAFKA_JMX_PORT=9101 \
-e KAFKA_JMX_HOSTNAME=localhost \
-e KAFKA_PROCESS_ROLES='broker,controller' \
-e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 \
-e KAFKA_CONTROLLER_QUORUM_VOTERS='1@kafka-kraft:29093' \
-e KAFKA_LISTENERS='PLAINTEXT://kafka-kraft:29092,CONTROLLER://kafka-kraft:29093,PLAINTEXT_HOST://0.0.0.0:9092' \
-e KAFKA_INTER_BROKER_LISTENER_NAME='PLAINTEXT' \
-e KAFKA_CONTROLLER_LISTENER_NAMES='CONTROLLER' \
-e CLUSTER_ID='MkU3OEVBNTcwNTJENDM2Qk' \
confluentinc/cp-kafka:8.0.2

`cp-server` example

The following examples show how to start cp-server in KRaft combined mode. Note that KRaft combined mode is for local experimentation only and is not supported by Confluent. For production configuration recommendations, see Production Configuration Options.

Generate a random-uuid using the kafka-storage tool:

/bin/kafka-storage random-uuid

Assign the output to the CLUSTER_ID variable:

docker run -d \
--name=kafka-kraft \
-h kafka-kraft \
-p 9101:9101 \
-e KAFKA_NODE_ID=1 \
-e KAFKA_LISTENER_SECURITY_PROTOCOL_MAP='CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT' \
-e KAFKA_ADVERTISED_LISTENERS='PLAINTEXT://kafka-kraft:29092,PLAINTEXT_HOST://localhost:9092' \
-e KAFKA_PROCESS_ROLES='broker,controller' \
-e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 \
-e KAFKA_CONTROLLER_QUORUM_VOTERS='1@kafka-kraft:29093' \
-e KAFKA_LISTENERS='PLAINTEXT://kafka-kraft:29092,CONTROLLER://kafka-kraft:29093,PLAINTEXT_HOST://0.0.0.0:9092' \
-e KAFKA_INTER_BROKER_LISTENER_NAME='PLAINTEXT' \
-e KAFKA_CONTROLLER_LISTENER_NAMES='CONTROLLER' \
-e CLUSTER_ID='q1Sh-9_ISia_zwGINzRvyQ' \
confluentinc/cp-server:8.0.2

`confluent-local` example

The confluent-local is configured to run in KRaft combined mode by default, and requires no configuration to start using it. Note that KRaft combined mode is for local experimentation only and is not supported by Confluent. For production configuration recommendations, see Production Configuration Options.

Following is an example of how to run confluent-local with the default configurations:

docker run -d -P --name=kafka-kraft confluentinc/confluent-local:8.0.2

For a list of the default configurations for this image, see the configureDefaults file on GitHub.

The following example shows how generate a cluster ID and specify the ID when you run the image.

/bin/kafka-storage random-uuid

Assign the output to the CLUSTER_ID variable:

docker run -d -P \
 --name=kafka-kraft \
  -e CLUSTER_ID=q1Sh-9_ISia_zwGINzRvyQ
   confluentinc/confluent-local:8.0.2

Confluent Schema Registry configuration

For the Schema Registry (cp-schema-registry) image, convert the property variables as below and use them as environment variables:

Prefix with SCHEMA_REGISTRY_.
Convert to upper-case.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

For example, run the following to set kafkastore.bootstrap.servers, host.name, listeners and debug:

docker run -d \
  --net=host \
  --name=schema-registry \
  -e SCHEMA_REGISTRY_KAFKASTORE_BOOTSTRAP_SERVERS=SSL://hostname2:9092 \
  -e SCHEMA_REGISTRY_HOST_NAME=localhost \
  -e SCHEMA_REGISTRY_LISTENERS=http://localhost:8081 \
  -e SCHEMA_REGISTRY_DEBUG=true \
  confluentinc/cp-schema-registry:8.0.2

Required Schema Registry configurations

SCHEMA_REGISTRY_KAFKASTORE_BOOTSTRAP_SERVERS: A list of Kafka brokers to connect to.
SCHEMA_REGISTRY_HOST_NAME: This is required if if you are running Schema Registry with multiple nodes. Hostname is required because it defaults to the Java canonical hostname for the container, which may not always be resolvable in a Docker environment. Hostname must be resolvable because secondary nodes serve registration requests indirectly by simply forwarding them to the current primary, and returning the response supplied by the primary. For more information, see the Schema Registry documentation on Single Primary Architecture.

Kafka Connect configuration

For the Kafka Connect (cp-kafka-connect) image, convert the property variables as below and use them as environment variables:

Prefix with CONNECT_.
Convert to upper-case.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

For example, run this command to set the required properties like bootstrap.servers, the topic names for config, offsets and status as well the key or value converter:

docker run -d \
  --name=kafka-connect \
  --net=host \
  -e CONNECT_BOOTSTRAP_SERVERS=localhost:29092 \
  -e CONNECT_REST_PORT=28082 \
  -e CONNECT_GROUP_ID="quickstart" \
  -e CONNECT_CONFIG_STORAGE_TOPIC="quickstart-config" \
  -e CONNECT_OFFSET_STORAGE_TOPIC="quickstart-offsets" \
  -e CONNECT_STATUS_STORAGE_TOPIC="quickstart-status" \
  -e CONNECT_KEY_CONVERTER="org.apache.kafka.connect.json.JsonConverter" \
  -e CONNECT_VALUE_CONVERTER="org.apache.kafka.connect.json.JsonConverter" \
  -e CONNECT_INTERNAL_KEY_CONVERTER="org.apache.kafka.connect.json.JsonConverter" \
  -e CONNECT_INTERNAL_VALUE_CONVERTER="org.apache.kafka.connect.json.JsonConverter" \
  -e CONNECT_REST_ADVERTISED_HOST_NAME="localhost" \
  -e CONNECT_PLUGIN_PATH=/usr/share/java \
  confluentinc/cp-kafka-connect:8.0.2

Required Kafka Connect configurations

The following configurations must be passed to run the Kafka Connect Docker image.

CONNECT_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
CONNECT_GROUP_ID: A unique string that identifies the Connect cluster group this worker belongs to.
CONNECT_CONFIG_STORAGE_TOPIC: The name of the topic in which to store connector and task configuration data. This must be the same for all workers with the same group.id
CONNECT_OFFSET_STORAGE_TOPIC: The name of the topic in which to store offset data for connectors. This must be the same for all workers with the same group.id
CONNECT_STATUS_STORAGE_TOPIC: The name of the topic in which to store state for connectors. This must be the same for all workers with the same group.id
CONNECT_KEY_CONVERTER: Converter class for keys. This controls the format of the data that will be written to Kafka for source connectors or read from Kafka for sink connectors.
CONNECT_VALUE_CONVERTER: Converter class for values. This controls the format of the data that will be written to Kafka for source connectors or read from Kafka for sink connectors.
CONNECT_REST_ADVERTISED_HOST_NAME: The hostname that is given out to other workers to connect to. In a Docker environment, your clients must be able to connect to the Connect and other services. Advertised hostname is how Connect gives out a hostname that can be reached by the client.
CONNECT_PLUGIN_PATH: The location from which to load Connect plugins in class loading isolation. If using the confluent-hub client, include /usr/share/confluent-hub-components, the default path that confluent-hub installs to.

Optional Kafka Connect configurations

The images marked as Commercially licensed include proprietary components and must be licensed from Confluent when deployed.

CONNECT_CONFLUENT_LICENSE: Required if using cp-server-connect or cp-server-connect-base Docker images. Without a license key, Kafka Connect can be used for a 30-day trial period. See Docker Image Reference for Confluent Platform for more information.

Note

To configure the JVM for Connect, you must use the KAFKA_HEAP_OPTS setting instead of CONNECT_KAFKA_HEAP_OPTS.

ksqlDB Server configuration

For a complete list of ksqlDB parameters, see ksqlDB Configuration Parameter Reference.

For the ksqlDB Server image (cp-ksqldb-server), convert the property variables as following and use them as environment variables:

Prefix with KSQL_.
Convert to upper-case.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

Enterprise support

For enterprise support, you must provide a license key for the ksqlDB Server and set the ksql.resource.extension.class property in the ksql-server.properties file to the following value. For more information, see Configure component licenses.

ksql.resource.extension.class=io.confluent.ksql.security.license.KsqlLicenseValidatorExtension

To set this property in a ksqlDB Server container, pass the following environment variable with the docker run command by using the -e or --env flags.

KSQL_KSQL_RESOURCE_EXTENSION_CLASS: The class that validates the license key.

docker run -d \
  -p 127.0.0.1:8088:8088 \
  -e KSQL_BOOTSTRAP_SERVERS=localhost:9092 \
  -e KSQL_LISTENERS=http://0.0.0.0:8088/ \
  -e KSQL_KSQL_SERVICE_ID=confluent_test_2 \
  -e KSQL_KSQL_RESOURCE_EXTENSION_CLASS=io.confluent.ksql.security.license.KsqlLicenseValidatorExtension \
  confluentinc/cp-ksqldb-server:8.0.2

Failing to assign this property causes ksqlDB to throw a warning saying that no license was found and no enterprise features or support will be provided. For more information, see Configure component licenses.

ksqlDB Headless Server configurations

Run a standalone ksqlDB Server instance in a container.

KSQL_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
KSQL_KSQL_SERVICE_ID: The service ID of the ksqlDB server, which is used as the prefix for the internal topics created by ksqlDB.
KSQL_KSQL_QUERIES_FILE: A file that specifies predefined SQL queries.

docker run -d \
  -v /path/on/host:/path/in/container/ \
  -e KSQL_BOOTSTRAP_SERVERS=localhost:9092 \
  -e KSQL_KSQL_SERVICE_ID=confluent_standalone_2_ \
  -e KSQL_KSQL_QUERIES_FILE=/path/in/container/queries.sql \
  confluentinc/cp-ksqldb-server:8.0.2

Interactive Server configuration

Run a ksqlDB Server that enables manual interaction by using the ksqlDB CLI.

KSQL_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
KSQL_KSQL_SERVICE_ID: The service ID of the ksqlDB server, which is used as the prefix for the internal topics created by ksqlDB.
KSQL_LISTENERS: A list of URIs, including the protocol, that the broker listens on.

docker run -d \
  -p 127.0.0.1:8088:8088 \
  -e KSQL_BOOTSTRAP_SERVERS=localhost:9092 \
  -e KSQL_LISTENERS=http://0.0.0.0:8088/ \
  -e KSQL_KSQL_SERVICE_ID=confluent_test_2 \
  confluentinc/cp-ksqldb-server:8.0.2

Connect to a secure Kafka cluster, like Confluent Cloud

Run a ksqlDB Server that uses a secure connection to a Kafka cluster. Learn about Configure Security for ksqlDB.

KSQL_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
KSQL_KSQL_SERVICE_ID: The service ID of the ksqlDB server, which is used as the prefix for the internal topics created by ksqlDB.
KSQL_LISTENERS: A list of URIs, including the protocol, that the broker listens on.
KSQL_KSQL_SINK_REPLICAS: The default number of replicas for the topics created by ksqlDB. The default is one.
KSQL_KSQL_STREAMS_REPLICATION_FACTOR: The replication factor for internal topics, the command topic, and output topics.
KSQL_SECURITY_PROTOCOL: The protocol that your Kafka cluster uses for security.
KSQL_SASL_MECHANISM: The SASL mechanism that your Kafka cluster uses for security.
KSQL_SASL_JAAS_CONFIG: The Java Authentication and Authorization Service (JAAS) configuration.

docker run -d \
  -p 127.0.0.1:8088:8088 \
  -e KSQL_BOOTSTRAP_SERVERS=REMOVED_SERVER1:9092,REMOVED_SERVER2:9093,REMOVED_SERVER3:9094 \
  -e KSQL_LISTENERS=http://0.0.0.0:8088/ \
  -e KSQL_KSQL_SERVICE_ID=default_ \
  -e KSQL_KSQL_SINK_REPLICAS=3 \
  -e KSQL_KSQL_STREAMS_REPLICATION_FACTOR=3 \
  -e KSQL_SECURITY_PROTOCOL=SASL_SSL \
  -e KSQL_SASL_MECHANISM=PLAIN \
  -e KSQL_SASL_JAAS_CONFIG="org.apache.kafka.common.security.plain.PlainLoginModule required username=\"<username>\" password=\"<strong-password>\";" \
  confluentinc/cp-ksqldb-server:8.0.2

Configure a ksqlDB Server by using Java system properties

Run a ksqlDB Server with a configuration that’s defined by Java properties.

KSQL_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
KSQL_OPTS: A space-separated list of Java options.

docker run -d \
  -v /path/on/host:/path/in/container/ \
  -e KSQL_BOOTSTRAP_SERVERS=localhost:9092 \
  -e KSQL_OPTS="-Dksql.service.id=confluent_test_3_  -Dksql.queries.file=/path/in/container/queries.sql" \
  confluentinc/cp-ksqldb-server:8.0.2

View logs

Use the docker logs command to view ksqlDB logs that are generated from within the container.

docker logs -f <container-id>
[2018-05-24 23:43:05,591] INFO stream-thread [_confluent-ksql-default_transient_1507119262168861890_1527205385485-71c8a94c-abe9-45ba-91f5-69a762ec5c1d-StreamThread-17] Starting (org.apache.kafka.streams.processor.internals.StreamThread:713)
...

ksqlDB CLI configuration

For the ksqlDB CLI image (cp-ksqldb-cli), convert the property variables as following and use them as environment variables:

Prefix with KSQL_.
Convert to upper-case.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

Connect to a Dockerized ksqlDB Server

Run a ksqlDB CLI instance in a container and connect to a ksqlDB Server that’s running in a container.

The Docker network created by ksqlDB Server enables you to connect to a Dockerized ksqlDB server.

KSQL_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
KSQL_OPTS: A space-separated list of Java options.

# Run ksqlDB Server.
docker run -d -p 10.0.0.11:8088:8088 \
  -e KSQL_BOOTSTRAP_SERVERS=localhost:9092 \
  -e KSQL_OPTS="-Dksql.service.id=confluent_test_3_ -Dlisteners=http://0.0.0.0:8088/" \
  confluentinc/cp-ksqldb-server:8.0.2

# Connect the ksqlDB CLI to the server.
docker run -it confluentinc/cp-ksqldb-cli http://10.0.0.11:8088
...
Copyright 2017 Confluent Inc.

CLI v8.0.2-SNAPSHOT, Server v8.0.2-SNAPSHOT located at http://10.0.0.11:8088

Having trouble? Type 'help' (case-insensitive) for a rundown of how things work!

ksql>

Provide a configuration file

Set up a a ksqlDB CLI instance by using a configuration file, and run it in a container.

# Assume ksqlDB Server is running.
# Ensure that the configuration file exists.
ls /path/on/host/ksql-cli.properties

docker run -it \
  -v /path/on/host/:/path/in/container  \
  confluentinc/cp-ksqldb-cli:8.0.2 http://10.0.0.11:8088 \
  --config-file /path/in/container/ksql-cli.properties

Connect to a ksqlDB Server running on another host, like AWS

Run a ksqlDB CLI instance in a container and connect to a remote ksqlDB Server host.

docker run -it confluentinc/cp-ksqldb-cli:8.0.2 \
  http://ec2-etc.us-etc.compute.amazonaws.com:8080

...
Copyright 2017 Confluent Inc.

CLI v8.0.2-SNAPSHOT, Server v8.0.2-SNAPSHOT located at http://ec2-blah.us-blah.compute.amazonaws.com:8080

Having trouble? Type 'help' (case-insensitive) for a rundown of how things work!

ksql>

Confluent REST Proxy configuration

The Confluent REST Proxy (cp-kafka-rest) image uses the REST Proxy configuration setting names. Convert the REST Proxy configurations to environment variables as below:

Prefix with KAFKA_REST_.
Convert to upper-case.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

For example, use the KAFKA_REST_SCHEMA_REGISTRY_URL environment variable to set schema.registry.url.

See Standalone REST Proxy Configuration Options for the configuration settings that REST Proxy supports.

The following command sets the listeners, schema.registry.url

docker run -d \
--net=host \
--name=kafka-rest \
-e KAFKA_REST_BOOTSTRAP_SERVERS=localhost:29092 \
-e KAFKA_REST_LISTENERS=http://localhost:8082 \
-e KAFKA_REST_SCHEMA_REGISTRY_URL=http://localhost:8081 \
confluentinc/cp-kafka-rest:8.0.2

Required Confluent REST Proxy configurations

The following configurations must be passed to run the REST Proxy Docker image.

KAFKA_REST_HOST_NAME: The hostname used to generate absolute URLs in responses. Hostname may be required because it defaults to the Java canonical hostname for the container, which may not always be resolvable in a Docker environment. For more information, see the Confluent Platform documentation on REST proxy deployment.
KAFKA_REST_BOOTSTRAP_SERVERS: A list of Kafka brokers to connect to. To learn about the corresponding bootstrap.server REST Proxy setting, see Standalone REST Proxy Configuration Options.

Confluent Control Center configuration

For the Confluent Control Center (cp-control-center) image, you must convert property variables used by Confluent Control Center to environment variables using the format described in the following table. In general, you:

Replace confluent.controlcenter in the property variable with CONTROL_CENTER_.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

Some of the properties have specific conversions where more general rules do not apply. Also, note some properties are required and some are optional. For more information, see Control Center Configuration.

Property variable	Environment variable replacement or pattern
`bootstrap.servers`	`CONTROL_CENTER_BOOTSTRAP_SERVERS`
`confluent.metrics.topic.replication`	`CONTROL_CENTER_METRICS_TOPIC_REPLICATION`
All other `confluent.metrics.topic.*` entries	`CONTROL_CENTER_METRICS_TOPIC_*`
`confluent.license`	`CONTROL_CENTER_LICENSE`
`public.key.path`	`PUBLIC_KEY_PATH`
All other `confluent.controlcenter.*` entries	`CONTROL_CENTER_*`
`confluent.metadata.*`	`CONFLUENT_METADATA_*`
`confluent.support.*`	`CONFLUENT_SUPPORT_*`

For example, confluent.controlcenter.mail.from property variable should be converted to the CONTROL_CENTER_MAIL_FROM environment variable.

The following example command runs Control Center, passing in Kafka, and Connect configuration parameters.

docker run -d \
  --net=host \
  --name=control-center \
  --ulimit nofile=16384:16384 \
  -e CONTROL_CENTER_BOOTSTRAP_SERVERS=localhost:29092 \
  -e CONTROL_CENTER_REPLICATION_FACTOR=1 \
  -e CONTROL_CENTER_CONNECT_connect-cluster-name_CLUSTER=http://localhost:28082 \
  -v /mnt/control-center/data:/var/lib/confluent-control-center \
  confluentinc/cp-enterprise-control-center:8.0.2

Control Center required configurations

The following configurations must be passed to run the Confluent Control Center image.

CONTROL_CENTER_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
CONTROL_CENTER_REPLICATION_FACTOR: Replication factor for Control Center topics. We recommend setting this to 3 in a production environment.

Control Center optional configurations

CONTROL_CENTER_CONNECT_<connect cluster name>_CLUSTER

To enable Control Center to interact with a Kafka Connect cluster, set this parameter to the REST endpoint URL for the Kafka Connect cluster.

CONTROL_CENTER_CONFLUENT_LICENSE

The Confluent Control Center license key. Without the license key, Confluent Control Center can be used for a 30-day trial period.

CONTROL_CENTER_KAFKA_<name>_BOOTSTRAP_SERVERS

To list bootstrap servers for any additional Kafka cluster being monitored, replace <name> with the name Control Center should use to identify this cluster. For example, using CONTROL_CENTER_KAFKA_production-nyc_BOOTSTRAP_SERVER, Control Center will show the additional cluster with the name production-nyc in the cluster list.

CONTROL_CENTER_LICENSE

The Confluent Control Center license key. Without the license key, Confluent Control Center can be used for a 30-day trial period.

CONTROL_CENTER_REST_LISTENERS

Set this to the HTTP or HTTPS of Control Center UI. If not set, you may see the following warning message:

WARN DEPRECATION warning: `listeners` configuration is not configured. Falling back to the deprecated `port` configuration. (io.confluent.rest.Application)

Control Center Docker options

File descriptor limit: Control Center may require many open files, so we recommend setting the file descriptor limit to at least 16384.
Data persistence: the Control Center image stores its data in the /var/lib/confluent-control-center directory. We recommend that you bind this to a volume on the host machine so that data is persisted across runs.

Confluent Replicator configuration

Confluent Replicator is a Kafka connector and runs on a Kafka Connect cluster.

For the Confluent Replicator image (cp-enterprise-replicator), convert the property variables as following and use them as environment variables:

Prefix with CONNECT_.
Convert to upper-case.
Separate each word with _.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

For example, run the following commands to set the properties, such as bootstrap.servers, confluent.license, the topic names for config, offsets, and status:

docker run -d \
  --name=cp-enterprise-replicator \
  --net=host \
  -e CONNECT_BOOTSTRAP_SERVERS=localhost:29092 \
  -e CONNECT_REST_PORT=28082 \
  -e CONNECT_GROUP_ID="quickstart" \
  -e CONNECT_CONFIG_STORAGE_TOPIC="quickstart-config" \
  -e CONNECT_OFFSET_STORAGE_TOPIC="quickstart-offsets" \
  -e CONNECT_STATUS_STORAGE_TOPIC="quickstart-status" \
  -e CONNECT_KEY_CONVERTER="org.apache.kafka.connect.json.JsonConverter" \
  -e CONNECT_VALUE_CONVERTER="org.apache.kafka.connect.json.JsonConverter" \
  -e CONNECT_INTERNAL_KEY_CONVERTER="org.apache.kafka.connect.json.JsonConverter" \
  -e CONNECT_INTERNAL_VALUE_CONVERTER="org.apache.kafka.connect.json.JsonConverter" \
  -e CONNECT_REST_ADVERTISED_HOST_NAME="localhost" \
  -e CONNECT_CONFLUENT_LICENSE="ABC123XYZ737BVT" \
  confluentinc/cp-enterprise-replicator:8.0.2

The following example shows how to create a Confluent Replicator connector which replicates topic “confluent” from source Kafka cluster (src) to a destination Kafka cluster (dest).

curl -X POST \
     -H "Content-Type: application/json" \
     --data '{
        "name": "confluent-src-to-dest",
        "config": {
          "connector.class":"io.confluent.connect.replicator.ReplicatorSourceConnector",
          "key.converter": "io.confluent.connect.replicator.util.ByteArrayConverter",
          "value.converter": "io.confluent.connect.replicator.util.ByteArrayConverter",
          "src.kafka.bootstrap.servers": "kafka-src:9082",
          "topic.whitelist": "confluent",
          "topic.rename.format": "${topic}.replica"}}'  \
            http://localhost:28082/connectors

Required Confluent Replicator configurations

The following configurations must be passed to run the Confluent Replicator Docker image:

CONNECT_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
CONNECT_GROUP_ID: A unique string that identifies the Connect cluster group this worker belongs to.
CONNECT_CONFIG_STORAGE_TOPIC: The name of the topic where connector and task configuration data is stored. This must be the same for all workers with the same group.id
CONNECT_OFFSET_STORAGE_TOPIC: The name of the topic where offset data for connectors is stored. This must be the same for all workers with the same group.id
CONNECT_STATUS_STORAGE_TOPIC: The name of the topic where state for connectors is stored. This must be the same for all workers with the same group.id
CONNECT_KEY_CONVERTER: Converter class for keys. This controls the format of the data that will be written to Kafka for source connectors or read from Kafka for sink connectors.
CONNECT_VALUE_CONVERTER: Converter class for values. This controls the format of the data that will be written to Kafka for source connectors or read from Kafka for sink connectors.
CONNECT_INTERNAL_KEY_CONVERTER: Converter class for internal keys that implements the Converter interface.
CONNECT_INTERNAL_VALUE_CONVERTER: Converter class for internal values that implements the Converter interface.
CONNECT_REST_ADVERTISED_HOST_NAME: The hostname that will be given out to other workers to connect to. In a Docker environment, your clients must be able to connect to the Connect and other services. Advertised hostname is how Connect gives out a hostname that can be reached by the client.

Optional Confluent Replicator configurations

CONNECT_CONFLUENT_LICENSE: The Confluent license key. Without the license key, Replicator can be used for a 30-day trial period.

Confluent Replicator Executable configuration

Confluent Replicator Executable (cp-enterprise-replicator-executable) provides another way to run Replicator by consolidating configuration properties and abstracting Connect details.

The image depends on input files that can be passed by mounting a directory with the expected input files or by mounting each file individually. Additionally, the image supports passing command line parameters to the Replicator executable via environment variables as well.

The following example will start Replicator given that the local directory /mnt/replicator/config, that will be mounted under /etc/replicator on the Docker image, contains the required files consumer.properties, producer.properties and the optional but often necessary file replication.properties.

docker run -d \
  --name=ReplicatorX \
  --net=host \
  -e REPLICATOR_LOG4J_ROOT_LOGLEVEL=DEBUG \
  -v /mnt/replicator/config:/etc/replicator \
  confluentinc/cp-enterprise-replicator-executable:8.0.2

In a similar example, we start Replicator by omitting to add a replication.properties and by specifying the replication properties by using environment variables.

For a complete list of the expected environment variables see the list of configurations in the next sections.

docker run -d \
  --name=ReplicatorX \
  --net=host \
  -e CLUSTER_ID=replicator-east-to-west \
  -e WHITELIST=confluent \
  -e TOPIC_RENAME_FORMAT='${topic}.replica' \
  -e REPLICATOR_LOG4J_ROOT_LOGLEVEL=DEBUG \
  -v /mnt/replicator/config:/etc/replicator \
  confluentinc/cp-enterprise-replicator-executable:8.0.2

Required Confluent Replicator Executable configurations

The following files must be passed to run the Replicator Executable Docker image:

CONSUMER_CONFIG: A file that contains the configuration settings for the consumer reading from the origin cluster. Default location is /etc/replicator/consumer.properties in the Docker image.
PRODUCER_CONFIG: A file that contains the configuration settings for the producer writing to the destination cluster. Default location is /etc/replicator/producer.properties in the Docker image.
CLUSTER_ID: A string that specifies the unique identifier for the Replicator cluster. Default value is replicator.

Optional Confluent Replicator Executable configurations

Additional configurations that are optional and maybe passed to Replicator Executable via environment variable instead of files are:

REPLICATION_CONFIG: A file that contains the configuration settings for the replication from the origin cluster. Default location is /etc/replicator/replication.properties in the Docker image.
CONSUMER_MONITORING_CONFIG: A file that contains the configuration settings of the producer writing monitoring information related to Replicator’s consumer. Default location is /etc/replicator/consumer-monitoring.properties in the Docker image.
PRODUCER_MONITORING_CONFIG: A file that contains the configuration settings of the producer writing monitoring information related to Replicator’s producer. Default location is /etc/replicator/producer-monitoring.properties in the Docker image.
BLACKLIST: A comma-separated list of topics that should not be replicated, even if they are included in the whitelist or matched by the regular expression.
WHITELIST: A comma-separated list of the names of topics that should be replicated. Any topic that is in this list and not in the blacklist will be replicated.
CLUSTER_THREADS: The total number of threads across all workers in the Replicator cluster.
CONFLUENT_LICENSE: The Confluent license key. Without the license key, Replicator can be used for a 30-day trial period.
TOPIC_AUTO_CREATE: Whether to automatically create topics in the destination cluster if required. If you disable automatic topic creation, Kafka Streams and ksqlDB applications continue to work. Kafka Streams and ksqlDB applications use the Admin Client, so topics are still created.
TOPIC_CONFIG_SYNC: Whether to periodically sync topic configuration to the destination cluster.
TOPIC_CONFIG_SYNC_INTERVAL_MS: Specifies how frequently to check for configuration changes when topic.config.sync is enabled.
TOPIC_CREATE_BACKOFF_MS: Time to wait before retrying auto topic creation or expansion.
TOPIC_POLL_INTERVAL_MS: Specifies how frequently to poll the source cluster for new topics matching the whitelist or regular expression.
TOPIC_PRESERVE_PARTITIONS: Whether to automatically increase the number of partitions in the destination cluster to match the source cluster and ensure that messages replicated from the source cluster use the same partition in the destination cluster.
TOPIC_REGEX: A regular expression that matches the names of the topics to be replicated. Any topic that matches this expression (or is listed in the whitelist) and not in the blacklist will be replicated.
TOPIC_RENAME_FORMAT: A format string for the topic name in the destination cluster, which may contain ${topic} as a placeholder for the originating topic name.
TOPIC_TIMESTAMP_TYPE: The timestamp type for the topics in the destination cluster.

Kafka MQTT Proxy configuration

For the Confluent MQTT Proxy Docker image, convert the property variables as following and use them as environment variables:

Prefix with KAFKA_MQTT_.
Convert to upper-case.
Replace a period (.) with a single underscore (_).
Replace an underscore (_) with double underscores (__).
Replace a dash (-) with triple underscores (___).

Required Kafka MQTT Proxy configurations

The following configurations must be passed to run the Confluent MQTT Proxy Docker image.

KAFKA_MQTT_BOOTSTRAP_SERVERS: A host:port pair for establishing the initial connection to the Kafka cluster. Multiple bootstrap servers can be used in the form host1:port1,host2:port2,host3:port3....
KAFKA_MQTT_TOPIC_REGEX_LIST: A comma-separated list of pairs of type ‘<kafka topic>:<regex>’ that is used to map MQTT topics to Kafka topics.