MirrorMaker 2 (MM2) is a tool that is included with Apache Kafka 2.4.0 and higher that can be used to keep multiple Apache Kafka clusters in sync as well as to fan-in and fan-out messages between clusters. Here are some of the high level features of MM2:
Leverages the Kafka Connect framework and ecosystem.
Includes both source and sink connectors.
Includes a high-level driver that manages connectors in a dedicated cluster.
Detects new topics, partitions.
Automatically syncs topic configuration between clusters.
Manages downstream topic ACL.
Supports “active/active” cluster pairs, as well as any number of active clusters.
Supports cross-datacenter replication, aggregation, and other complex topologies.
Provides new metrics including end-to-end replication latency across multiple data centers/clusters.
Emits offsets required to migrate consumers between clusters.
Tooling for offset translation.
MirrorMaker-compatible legacy mode.
To read more about MM2, see KIP-382