Migrate Data to Redpanda with MirrorMaker 2

When you want to migrate data from Kafka or replicate data between Redpanda clusters, you can use the MirrorMaker 2 (MM2) tool bundled in the Kafka download package. This section describes the process of configuring MirrorMaker 2 to replicate data from one Redpanda cluster to another.

MirrorMaker 2 reads a configuration file that specifies the connection details for the Redpanda clusters, as well as other options. After you start MirrorMaker 2, the data migration continues according to the configuration at launch time until you shutdown the MirrorMaker 2 process.

See the Kafka downloads page for download instructions, and the Kafka documentation for details on cross-cluster data mirroring with MirrorMaker 2.

Prerequisites

To set up the replication, you need:

  • 2 Redpanda clusters - You can set up these clusters in any deployment you like, including Kubernetes, Docker, and Linux.

  • MirrorMaker 2 host - You install MirrorMaker 2 on a separate system or on one of the Redpanda clusters, as long as the IP addresses and ports on each cluster are accessible from the MirrorMaker 2 host. You must install the Java Runtime Engine (JRE) on the MirrorMaker 2 host.

Install MirrorMaker 2

MirrorMaker 2 is run by a shell script that is part of the Kafka download package. To install MirrorMaker 2 on the machine that you want to run the replication between the clusters:

  1. Download the latest Kafka download package. For example:

    curl -O https://dlcdn.apache.org/kafka/3.3.1/kafka_2.13-3.3.1.tgz

  2. Extract the files from the archive:

    tar -xvf kafka_2.13-3.3.1.tgz

Create the MirrorMaker 2 configuration files

MirrorMaker 2 uses configuration files to get the connection details for the clusters. You can find the MirrorMaker 2 script and configuration files in the expanded Kafka directory.

.
└── kafka_2.13-3.3.1
    └── bin
        └── connect-mirror-maker.sh
    └── config
        └── connect-mirror-maker.properties

The sample configuration describes a number of the settings for MirrorMaker 2.

To create a basic configuration file, go to the config and run:

cat << EOF > mm2.properties
// Name the clusters
clusters = <cluster_name_1>, <cluster_name_2>

// Assign IP addresses to the cluster names
<cluster_name_1>.bootstrap.servers = <cluster_1_ip>:9092
<cluster_name_2>.bootstrap.servers = <cluster_2_ip>:9092

// Set replication for all topics from Redpanda 1 to Redpanda 2
<cluster_name_1>-><cluster_name_2>.enabled = true
<cluster_name_1>-><cluster_name_2>.topics = .*

// Setting replication factor of newly created remote topics
replication.factor = 1

//Make sure that your target cluster can accept larger message sizes. For example, 30MB messages
<cluster_name_2>.producer.max.request.size=31457280

//Make sure topics are created without a prefix
replication.policy.class=org.apache.kafka.connect.mirror.IdentityReplicationPolicy
EOF
Remember to edit the variable names on the examples for your environment. For example, <cluster_name_1> can become redpanda_1.

Run MirrorMaker 2 to start replication

To start MirrorMaker 2 in the kafka_2.13-3.3.1/bin/ directory, run:

./kafka_2.13-3.3.1/bin/connect-mirror-maker.sh mm2.properties

With this command, MirrorMaker 2 consumes all topics from the <cluster_name_1> cluster and replicates them into the <cluster_name_2> cluster. MirrorMaker 2 adds the prefix <cluster_name_1> to the names of replicated topics.

Change topic replication factor

The replication.factor property is a topic property set at topic creation. A replication factor of three generally provides a good balance between broker loss and replication overhead.

You can increase or decrease the replication factor on an existing topic. For example, if topics were initially created in a test environment with a replication factor of 1 (no replication), to change the topic replication factor to 3, run:

rpk topic alter-config [TOPICS...] --set replication.factor=3

See migration in action

Here are the basic commands to produce and consume streams:

  1. Create a topic in the source cluster called "twitch_chat":

     rpk topic create twitch_chat -X brokers=<node IP>:<kafka API port>

  2. Produce messages to the topic:

     rpk topic produce twitch_chat -X brokers=<node IP>:<kafka API port>

    Type text into the topic and press Ctrl + D to separate between messages.

    Press Ctrl + C to exit the produce command.

  3. Consume (read) the messages from the destination cluster:

     rpk topic consume twitch_chat -X brokers=<node IP>:<kafka API port>

    Each message is shown with its metadata like the following:

     {
    "message": "How do you stream with Redpanda?\n",
    "partition": 0,
    "offset": 1,
    "timestamp": "2021-02-10T15:52:35.251+02:00"
 }

Now you know the replication is working.

Stop MirrorMaker 2

To stop the MirrorMaker 2 process, use top to find its process ID, and then run: kill <MirrorMaker 2 pid>

Message size

When replicating larger message sizes with MirrorMaker 2 on the target cluster, you may get blocked with an error:

org.apache.kafka.common.errors.RecordTooLargeException: The message is xxxx bytes when serialized which is larger than 1048576, which is the value of the max.request.size configuration.

To address this issue, make sure that your mm2.properties configuration file on the target cluster allows bigger messages sizes. For example, for 30MB messages, you’d have the following line in the configuration file:

<cluster_name_2>.producer.max.request.size=31457280

Running MirrorMaker 2 as a service

For production usage Redpanda recommends that you run MirrorMaker 2 as a systemd unit file.

To run MirrorMaker 2 as a systemd unit file:

  1. Edit /etc/systemd/system/multi-user.target.wants/mm2.service and add the following:

    [Unit]
Description=Mirror Maker 2 service
After=network.target
#StartLimitIntervalSec=0
[Service]
Type=simple
Restart=always
LimitNOFILE=49152
RestartSec=1
User=root
Environment=JAVA_HOME=/usr/lib/jvm/java-11-amazon-corretto
ExecStart=/home/ec2-user/kafka_2.13-3.3.1/bin/connect-mirror-maker.sh /home/ec2-user/mm2.properties

# Output to syslog
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=mm2

[Install]
WantedBy=multi-user.target
    The home directory and where you are running MirrorMaker2 from may vary. Note the Kafka folder location, as it may vary by version.

  2. Run:

    sudo systemctl daemon-reload

  3. Run:

    sudo systemctl start mm2.service

You can follow the progress with the tail command:

  • Fedora/RedHat

  • Debian/Ubuntu

tail -f /var/log/messages | grep mm2
tail -f /var/log/syslog | grep mm2

Troubleshooting

If you run into any difficulty with data migration, you can request help in the Redpanda Slack community.