Project Url: salesforce/mirus
Introduction: Mirus is a cross data-center data replication tool for Apache Kafka
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A tool for distributed, high-volume replication between Apache Kafka clusters based on Kafka Connect. Designed for easy operation in a high-throughput, multi-cluster environment.


  • Dynamic Configuration: Uses the Kafka Connect REST API for dynamic API-driven configuration
  • Precise Replication: Supports a regex whitelist and an explicit topic whitelist
  • Simple Management for Multiple Kafka Clusters: Supports multiple source clusters with one Worker process
  • Continuous Ingestion: Continues consuming from the source cluster while flushing and committing offsets
  • Built for Dynamic Kafka Clusters: Able to handle topics and partitions being created and deleted in source and destination clusters
  • Scalable: Creates a configurable set of worker tasks that are distributed across a Kafka Connect cluster for high performance, even when pushing data over the internet
  • Fault tolerant: Includes a monitor thread that looks for task failures and optionally auto-restarts
  • Monitoring: Includes custom JMX metrics for production ready monitoring and alerting


Mirus is built around Apache Kafka Connect, providing SourceConnector and SourceTask implementations optimized for reading data from Kafka source clusters. The MirusSourceConnector runs a KafkaMonitor thread, which monitors the source and destination Apache Kafka cluster partition allocations, looking for changes and applying a configurable topic whitelist. Each task is responsible for a subset of the matching partitions, and runs an independent KafkaConsumer and KafkaProducer client pair to do the work of replicating those partitions.

Tasks can be restarted independently without otherwise affecting a running cluster, are monitored continuously for failure, and are optionally automatically restarted.

To understand how Mirus distributes work across a cluser of machines please read the Kafka Connect documentation.


To build a package containing the Mirus jar file and all dependencies, run mvn package -P all:

  • target/mirus-${project.version}-all.zip

This package can be unzipped for use (see Quick Start).

Maven also builds the following artifacts when you run mvn package. These are useful if you need customized packaging for your own environment:

  • target/mirus-${project.version}.jar: Primary Mirus jar (dependencies not included)
  • target/mirus-${project.version}-run.zip: A package containing the Mirus run control scripts


These instructions assume you have expanded the mirus-${project.version}-all.zip package.

Mirus Worker Instance

A single Mirus Worker can be started using this helper script.

> bin/mirus-worker-start.sh [worker-properties-file]

worker-properties-file: Path to the Mirus worker properties file, which configures the Kafka Connect framework. See quickstart-worker.properties for an example.


--override property=value: optional command-line override for any item in the Mirus worker properties file. Multiple override options are supported (similar to the equivalent flag in Kafka).

Mirus Offset Tool

Mirus includes a simple tool for reading and writing offsets. This can be useful for migration from other replication tools, for debugging, and for offset monitoring in production. The tool supports CSV and JSON input and output.

For detailed usage:

> bin/mirus-offset-tool.sh --help

Quick Start

To run the Quick Start example you will need running Kafka and Zookeeper clusters to work with. We will assume you have a standard Apache Kafka Quickstart test cluster running on localhost. Follow the Kafka Quick Start instructions.

For this tutorial we will set up a Mirus worker instance to mirror the topic test in loop-back mode to another topic in the same cluster. To avoid a conflict the destination topic name will be set to test.mirror using the destination.topic.name.suffix configuration option.

  1. Build the full Mirus project using Maven

     > mvn package -P all
  2. Unpack the Mirus "all" package

     > mkdir quickstart; cd quickstart; unzip ../target/mirus-*-all.zip
  3. Start the quickstart worker using the sample worker properties file

     > bin/mirus-worker-start.sh config/quickstart-worker.properties
  4. In another terminal, confirm the Mirus Kafka Connect REST API is running

     > curl localhost:8083
  5. Submit a new MirusSourceConnector configuration to the REST API with the name mirus-quickstart-source

     > curl localhost:8083/connectors/mirus-quickstart-source/config \
           -X PUT \
           -H 'Content-Type: application/json' \
           -d '{
                "name": "mirus-quickstart-source",
                "connector.class": "com.salesforce.mirus.MirusSourceConnector",
                "tasks.max": "5",
                "topics.whitelist": "test",
                "destination.topic.name.suffix": ".mirror",
                "destination.consumer.bootstrap.servers": "localhost:9092",
                "consumer.bootstrap.servers": "localhost:9092",
                "consumer.client.id": "mirus-quickstart",
                "consumer.key.deserializer": "org.apache.kafka.common.serialization.ByteArrayDeserializer",
                "consumer.value.deserializer": "org.apache.kafka.common.serialization.ByteArrayDeserializer"
  6. Confirm the new connector is running

     > curl localhost:8083/connectors
     > curl localhost:8083/connectors/mirus-quickstart-source/status
  7. Create source and destination topics test and test.mirror in your Kafka cluster

     > cd ${KAFKA_HOME}
     > bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic 'test' --partitions 1 --replication-factor 1
     Created topic "test".
     > bin/kafka-topics.sh --zookeeper localhost:2181 --create --topic 'test.mirror' --partitions 1 --replication-factor 1
     Created topic "test.mirror".
  8. Mirus should detect that the new source and destination topics are available and create a new Mirus Source Task:

     > curl localhost:8083/connectors/mirus-quickstart-source/status

Any message you write to the topic test will now be mirrored to test.mirror.


See the documentation for Kafka Connect REST API.


Kafka Connect Configuration

Mirus shares most Worker and Source configuration with the Kafka Connect framework. For general information on configuring the framework see:

Mirus Specific Configuration

Mirus-specific configuration properties are documented in these files:

  • Mirus Source Properties These can be added to the JSON config object posted to the REST API /config endpoint to configure a new MirusSourceConnector instance. In addition, the Kafka Consumer instances created by Mirus Tasks can be configured using a consumer. prefix on the standard Kafka Consumer properties. The equivalent KafkaProducer options are configured in the Mirus Worker Properties file (see below). The destination.consumer.prefix can be used to override the properties of the KafkaConsumer that connects to the destination Kafka cluster.

  • Mirus Worker Properties These are Mirus extensions to the Kafka Connect configuration, and should be applied to the Worker Properties file provided at startup. The Kafka Producer instances created by Kafka Connect can also be configured using a producer. prefix on the standard Kafka Producer properties.

Destination Topic Checking

By default, Mirus checks that the destination topic exists in the destination Kafka cluster before starting to replicate data to it. This feature can be disabled by setting the enable.destination.topic.checking config option to false.

As of version 0.2.0, destination topic checking can also support topic re-routing performed by the RegexRouter Single-Message Transformation. No other Router Transformations are supported, so destination topic checking must be disabled in order to use them.


Mirus produces some custom metrics in addition to the standard Kafka Connect metrics.

JMX Queries are as follows

Latency (MirrorJmxReporter)

objectName="mirus:type=MirusSourceConnector,topic=*" attribute="replication-latency-ms-max"
objectName="mirus:type=MirusSourceConnector,topic=*" attribute="replication-latency-ms-min"
objectName="mirus:type=MirusSourceConnector,topic=*" attribute="replication-latency-ms-avg"
objectName="mirus:type=MirusSourceConnector,topic=*" attribute="replication-latency-ms-count"

Destination Information (MissingPartitionsJmxReporter)

objectName="mirus:type=mirus" attribute="missing-dest-partitions-count"

Connector Metrics (ConnectorJmxReporter)

objectName="mirus:type=connector-metrics,connector=*" attribute="task-failed-restart-attempts-count"
objectName="mirus:type=connector-metrics,connector=*" attribute="connector-failed-restart-attempts-count"
objectName="mirus:type=connector-metrics,connector=*" attribute="failed-task-count"
objectName="mirus:type=connector-metrics,connector=*" attribute="paused-task-count"
objectName="mirus:type=connector-metrics,connector=*" attribute="destroyed-task-count"
objectName="mirus:type=connector-metrics,connector=*" attribute="running-task-count"
objectName="mirus:type=connector-metrics,connector=*" attribute="unassigned-task-count"

Task Metrics (TaskJmxReporter)

objectName="mirus:type=connector-task-metrics,connector=*" attribute="task-failed-restart-attempts-count"

Developer Info

To preform a release: mvn release:prepare release:perform GPG Keys may need to be passed to maven with -Darguments='-Dgpg.passphrase= -Dgpg.keyname=55Z32RD1'


Questions or comments can also be posted on the Mirus Github issues page.


Paul Davidson and contributors.

Code Style

This project uses the Google Java Format.

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