connection-check

connection-check

Use the Java Kafka client to check for a connection to a Kafka cluster. Sometimes, this is called a health check.

Instructions

Follow these instructions to get up and running with Kafka and run the example program.

1. Pre-requisites: Java, Kafka and kcat
   • I used Java 21 installed via SDKMAN.
   • I used Kafka 3.8.0 installed via Homebrew.
   • I used kcat 1.7.0 installed via Homebrew.
   • Tip: check your HomeBrew-installed package versions with a command like the following.

   •  brew list --versions kafka

2. Build the program distribution

   • ./gradlew installDist

3. Run the connection-check program

   • ./build/install/connection-check/bin/connection-check

   • Notice that it continuously yields a "COULD NOT CONNECT ❌" message every few because the Kafka instance is not running.
4. Start Kafka

   • ./scripts/start-kafka.sh

   • Wait for a few seconds, and notice that the connection-check program now yields a "CONNECTED ✅" message!
5. When done, stop Kafka

   • ./scripts/stop-kafka.sh

Altogether, the connection-check program will output something like this:

./build/install/connection-check/bin/connection-check

> Task :run
15:02:11 ERROR ConnectionCheckMain - Kafka connection-check: COULD NOT CONNECT ❌
15:02:21 ERROR ConnectionCheckMain - Kafka connection-check: COULD NOT CONNECT ❌
15:02:27 INFO ConnectionCheckMain - Kafka connection-check: CONNECTED ✅
15:02:32 INFO ConnectionCheckMain - Kafka connection-check: CONNECTED ✅
15:02:42 ERROR ConnectionCheckMain - Kafka connection-check: COULD NOT CONNECT ❌
15:02:52 ERROR ConnectionCheckMain - Kafka connection-check: COULD NOT CONNECT ❌

Notes

For a Java program, I think using the AdminClient is the most idiomatic way to check for a connection to a Kafka cluster.

The amount of logs coming out of the Kafka client is verbose, and doubly so because this program instantiates a new instance of the Kafka Admin type for each connection attempt, but this is the best I could come up with.