How to ensure that a message in Kafka reaches from one pod to another?

To ensure that a message in Kafka is delivered from one pod to another, several levels need to be checked:

1. Producer: make sure the message is successfully sent to Kafka. You can use acknowledgments (acks) from the broker — setting acks=all guarantees that the message is written to all replicas.

2. Kafka Broker: verify that the message is actually written to the topic. You can use Kafka tools (e.g., kafka-console-consumer) to read messages from the topic.

3. Consumer: ensure that the other pod has successfully read the message. To do this:

   • Check the consumer logs for successful receipt and processing of the message.
   • Use offset management — if the offset has moved, it means the message has been read.

4. Monitoring and metrics: set up monitoring for delays, errors, and delivery confirmations.

5. Testing: you can write an integration test that sends a test message and checks its receipt.

Thus, guaranteeing delivery involves configuring the correct Kafka parameters (acks, retries), monitoring, and checking the consumer's offset.