Kafka Tools – kafka.tools.ReplayLogProducer
Replay Log Producer is a Kafka tool available to copy messages from one Kafka Topic to the other in the same Broker cluster. This supports copying a limited or all messages from a Kafka Topic. The tool is specially useful in a development environment when we want to test something with a limited number of messages first.
Here are some of the options available to run the tool:
The input and output topics are specified through the inputtopic and outputtopic switches respectively.
Let’s startup Landoop’s Kafka Topics UI tool to see the messages as they are copied to our new topics. It should start running on port 8000.
Copying Limited Messages
The tool supports copying a limited number of messages by specifying the messages switch when running the tool. Here we are just copying one message from Merged-SensorsHeartbeat topic to another topic with name Destination-Topic-Limited.
We can see the new topic being created. We can also notice that only one message is copied to the topic, which is what we expected.
Copying the whole Topic
If we don’t specify messages switch at all, then it just uses the default value, which is -1.
Surely, all the messages are copied to Destination-Topic-All topic.
I have noticed that the tool warns you if topic doesn’t already exist. Apparently, you can ignore this for new topic.