.. _migrate-replicator:

###################################
Migrate from |mmaker| to Replicator
###################################

This topic provides examples of how to migrate from an existing datacenter that is using |mmaker| to Replicator. In these
examples, messages are replicated from a specific point in time, not from the beginning. This is helpful if you have a
large number of legacy messages that you do not want to migrate.

Assume there are two datacenters, DC1 (Active) and DC2 (Passive), that are each running a |ak-tm| cluster. There is a single
topic in DC1 and it has been replicated to DC2 with the same topic name. The topic name is ``inventory``.

.. include:: ../includes/replicator-topic-preserve.rst

.. _samepartition:

***************************************************
Example 1: Same Number of Partitions in DC1 and DC2
***************************************************

In this example, you migrate from |mmaker| to Replicator and keep the same number of partitions for ``inventory`` in DC1 and
DC2.

Prerequisites:
    - |cp| 5.0.0 or later is :ref:`installed <installation>`.
    - You must have the same number of partitions for ``inventory`` in DC1 and DC2 to use this method.
    - The ``src.consumer.group.id`` in Replicator must match ``group.id`` in |mmaker|.

#.  Stop the running |mmaker| instance in DC1, where ``<mm pid>`` is the |mmaker| process ID.

    ::

        kill <mm pid>

#.  Configure and start Replicator. In this example, Replicator is run as an executable from the command line or from
    :ref:`a Docker image <config_reference>`.

    #. Add these values to ``<path-to-confluent>/etc/kafka-connect-replicator/replicator_consumer.properties``. Replace
       ``localhost:9082`` with the ``bootstrap.servers`` of DC1, the source cluster:

       .. codewithvars:: bash

            bootstrap.servers=localhost:9082
            topic.preserve.partitions=true

    #. Add this value to ``<path-to-confluent>/etc/kafka-connect-replicator/replicator_producer.properties``. Replace
       ``localhost:9092`` with the ``bootstrap.servers`` of DC2, the destination cluster:

       .. codewithvars:: bash

            bootstrap.servers=localhost:9092

    #.  Ensure the replication factors are set to ``2`` or ``3`` for production, if they are not already:

        .. codewithvars:: bash

            echo "confluent.topic.replication.factor=3" >> ./etc/kafka-connect-replicator/quickstart-replicator.properties
            echo "offset.storage.replication.factor=3" >> ./etc/kafka-connect-replicator/quickstart-replicator.properties
            echo "config.storage.replication.factor=3" >> ./etc/kafka-connect-replicator/quickstart-replicator.properties
            echo "status.storage.replication.factor=3" >> ./etc/kafka-connect-replicator/quickstart-replicator.properties

    #.  Start Replicator.

        .. codewithvars:: bash

          <path-to-confluent>/bin/replicator --cluster.id <new-cluster-id> \
          --producer.config replicator_producer.properties \
          --consumer.config replicator_consumer.properties \
          --replication.config ./etc/kafka-connect-replicator/quickstart-replicator.properties

Replicator will use the committed offsets by |mmaker| from DC1 and start replicating messages from DC1 to DC2 based on
these offsets.

.. _diffpartition:

********************************************************
Example 2: Different Number of Partitions in DC1 and DC2
********************************************************

In this example, you migrate from |mmaker| to Replicator and have a different number of partitions for ``inventory`` in DC1
and DC2.

Prerequisite:
    - |cp| 5.0.0 or later is :ref:`installed <installation>`.
    - The ``src.consumer.group.id`` in Replicator must match ``group.id`` in |mmaker|.

#.  Stop the running |mmaker| instance from DC1.

#.  Configure and start Replicator. In this example, Replicator is run as an executable from the command line or from
    :ref:`a Docker image <config_reference>`.

    #. Add this value to ``<path-to-confluent>/etc/kafka-connect-replicator/replicator_consumer.properties``. Replace
       ``localhost:9082`` with the ``bootstrap.servers`` of DC1, the source cluster:

       .. codewithvars:: bash

            bootstrap.servers=localhost:9082
            topic.preserve.partitions=false

    #. Add this value to ``<path-to-confluent>/etc/kafka-connect-replicator/replicator_producer.properties``. Replace
       ``localhost:9092`` with the ``bootstrap.servers`` of DC2, the destination cluster:

       .. codewithvars:: bash

            bootstrap.servers=localhost:9092

    #.  Ensure the replication factors are set to ``2`` or ``3`` for production, if they are not already:

        .. codewithvars:: bash

            echo "confluent.topic.replication.factor=3" >> ./etc/kafka-connect-replicator/quickstart-replicator.properties
            echo "offset.storage.replication.factor=3" >> ./etc/kafka-connect-replicator/quickstart-replicator.properties
            echo "config.storage.replication.factor=3" >> ./etc/kafka-connect-replicator/quickstart-replicator.properties
            echo "status.storage.replication.factor=3" >> ./etc/kafka-connect-replicator/quickstart-replicator.properties

    #.  Start Replicator.

        .. codewithvars:: bash

          <path-to-confluent>/bin/replicator --cluster.id <new-cluster-id> \
          --producer.config replicator_producer.properties \
          --consumer.config replicator_consumer.properties \
          --replication.config ./etc/kafka-connect-replicator/quickstart-replicator.properties

Replicator will use the committed offsets by |mmaker| from DC1 and start replicating messages from DC1 to DC2 based on
these offsets.