feat: create client.properties for use with kafka scripts

CHANGELOG.md

@@ -10,6 +10,10 @@ All notable changes to this project will be documented in this file.
 - Add experimental support for Kafka KRaft mode ([#889]).
 - Add experimental support for Kafka `4.1.0` ([#889]).
 - Add `prometheus.io/path|port|scheme` annotations to metrics service ([#897]).
+- Add `client.properties` to the Kafka configuration config map ([#898]).
+
+  Use this file together with the Kafka client shell scripts and preconfigured TLS settings.
+  Unfortunately, when Kerberos is enabled this file is incomplete and must be edited first before it can be used.
 
 ### Changed
 
@@ -21,11 +25,15 @@ All notable changes to this project will be documented in this file.
   - use the new `server.yaml` for jmx configuration
   - update metrics tests
   - update monitoring doc
+- Replace `kcat` with Kafka client scripts wherever possible ([#898]).
+
+  At the moment, `kcat` is still used for liveliness probes and Kerberos tests.
 
 [#889]: https://github.com/stackabletech/kafka-operator/pull/889
 [#890]: https://github.com/stackabletech/kafka-operator/pull/890
 [#892]: https://github.com/stackabletech/kafka-operator/pull/892
 [#897]: https://github.com/stackabletech/kafka-operator/pull/897
+[#898]: https://github.com/stackabletech/kafka-operator/pull/898
 [#900]: https://github.com/stackabletech/kafka-operator/pull/900
 
 ## [25.7.0] - 2025-07-23

docs/modules/kafka/examples/getting_started/getting_started.sh

@@ -90,28 +90,33 @@ trap "kill $PORT_FORWARD_PID" EXIT
 
 sleep 15
 
-echo "Creating test data"
-# tag::kcat-create-data[]
-echo "some test data" > data
-# end::kcat-create-data[]
-
-echo "Writing test data"
-# tag::kcat-write-data[]
-kcat -b localhost:9092 -t test-data-topic -P data
-# end::kcat-write-data[]
-
-echo "Reading test data"
-# tag::kcat-read-data[]
-kcat -b localhost:9092 -t test-data-topic -C -e > read-data.out
-# end::kcat-read-data[]
-
-echo "Check contents"
-# tag::kcat-check-data[]
-grep "some test data" read-data.out
-# end::kcat-check-data[]
-
-echo "Cleanup"
-# tag::kcat-cleanup-data[]
-rm data
-rm read-data.out
-# end::kcat-cleanup-data[]
+echo "Creating test topic test-data-topic"
+# tag::create-topic[]
+kubectl exec -n default simple-kafka-broker-default-0 -c kafka -t -- /stackable/kafka/bin/kafka-topics.sh \
+--create \
+--topic test-data-topic \
+--partitions 1 \
+--bootstrap-server localhost:9092
+# end::create-topic[]
+
+echo "Publish test data"
+# tag::write-data[]
+kubectl exec -n default simple-kafka-broker-default-0 -c kafka -t -- /stackable/kafka/bin/kafka-producer-perf-test.sh \
+--producer-props bootstrap.servers=localhost:9092 \
+--topic test-data-topic \
+--payload-monotonic \
+--throughput 1 \
+--num-records 5
+# end::write-data[]
+
+echo "Consume test data"
+# tag::read-data[]
+kubectl exec -n default simple-kafka-broker-default-0 -c kafka -t -- /stackable/kafka/bin/kafka-console-consumer.sh \
+--bootstrap-server localhost:9092 \
+--topic test-data-topic \
+--offset earliest \
+--partition 0 \
+--timeout-ms 1000
+# end::read-data[]
+
+echo "Success!"

docs/modules/kafka/examples/getting_started/getting_started.sh.j2

@@ -90,28 +90,33 @@ trap "kill $PORT_FORWARD_PID" EXIT
 
 sleep 15
 
-echo "Creating test data"
-# tag::kcat-create-data[]
-echo "some test data" > data
-# end::kcat-create-data[]
-
-echo "Writing test data"
-# tag::kcat-write-data[]
-kcat -b localhost:9092 -t test-data-topic -P data
-# end::kcat-write-data[]
-
-echo "Reading test data"
-# tag::kcat-read-data[]
-kcat -b localhost:9092 -t test-data-topic -C -e > read-data.out
-# end::kcat-read-data[]
-
-echo "Check contents"
-# tag::kcat-check-data[]
-grep "some test data" read-data.out
-# end::kcat-check-data[]
-
-echo "Cleanup"
-# tag::kcat-cleanup-data[]
-rm data
-rm read-data.out
-# end::kcat-cleanup-data[]
+echo "Creating test topic test-data-topic"
+# tag::create-topic[]
+kubectl exec -n default simple-kafka-broker-default-0 -c kafka -t -- /stackable/kafka/bin/kafka-topics.sh \
+--create \
+--topic test-data-topic \
+--partitions 1 \
+--bootstrap-server localhost:9092
+# end::create-topic[]
+
+echo "Publish test data"
+# tag::write-data[]
+kubectl exec -n default simple-kafka-broker-default-0 -c kafka -t -- /stackable/kafka/bin/kafka-producer-perf-test.sh \
+--producer-props bootstrap.servers=localhost:9092 \
+--topic test-data-topic \
+--payload-monotonic \
+--throughput 1 \
+--num-records 5
+# end::write-data[]
+
+echo "Consume test data"
+# tag::read-data[]
+kubectl exec -n default simple-kafka-broker-default-0 -c kafka -t -- /stackable/kafka/bin/kafka-console-consumer.sh \
+--bootstrap-server localhost:9092 \
+--topic test-data-topic \
+--offset earliest \
+--partition 0 \
+--timeout-ms 1000
+# end::read-data[]
+
+echo "Success!"

docs/modules/kafka/pages/getting_started/first_steps.adoc

@@ -1,6 +1,5 @@
 = First steps
-:description: Deploy and verify a Kafka cluster on Kubernetes with Stackable Operators, including ZooKeeper setup and data testing using kcat.
-:kcat-install: https://github.com/edenhill/kcat#install
+:description: Deploy and verify a Kafka cluster on Kubernetes with Stackable Operators, including ZooKeeper setup and data testing.
 
 After going through the xref:getting_started/installation.adoc[] section and having installed all the operators, you now deploy a Kafka cluster and the required dependencies.
 Afterward you can <<_verify_that_it_works, verify that it works>> by producing test data into a topic and consuming it.
@@ -65,58 +64,90 @@ This creates the actual Kafka instance.
 
 == Verify that it works
 
-Next you produce data into a topic and read it via {kcat-install}[kcat].
-Depending on your platform you may need to replace `kafkacat` in the commands below with `kcat`.
+Next, use the Kafka client scripts to create a topic and publish and consume data.
 
-First, make sure that all the Pods in the StatefulSets are ready:
+The Kafka operator has created a service called `simple-kafka-broker-default-bootstrap`.
+This service represents the endpoint clients should initially connect to in order to publish and consume data.
+First, make sure that the service exists and it is healthy:
 
 [source,bash]
 ----
-kubectl get statefulset
+kubectl describe svc simple-kafka-broker-default-bootstrap
 ----
 
-The output should show all pods ready:
+The output should look somewhat like this:
 
 ----
-NAME                                 READY   AGE
-simple-kafka-broker-default          3/3     5m
-simple-zk-server-default             3/3     7m
+Name:                     simple-kafka-broker-default-bootstrap
+Namespace:                default
+Labels:                   app.kubernetes.io/component=broker
+                          app.kubernetes.io/instance=simple-kafka-broker-default-bootstrap
+                          app.kubernetes.io/managed-by=listeners.stackable.tech_listener
+                          app.kubernetes.io/name=listener
+                          app.kubernetes.io/role-group=default
+                          app.kubernetes.io/version=3.9.1-stackable0.0.0-dev
+                          stackable.tech/vendor=Stackable
+Annotations:              <none>
+Selector:                 listener.stackable.tech/mnt.9555cbb6f38d4b0ca1771e6d83d28e27=simple-kafka-broker-default-bootstrap
+Type:                     NodePort
+IP Family Policy:         SingleStack
+IP Families:              IPv4
+IP:                       10.105.88.52
+IPs:                      10.105.88.52
+Port:                     kafka  9092/TCP
+TargetPort:               9092/TCP
+NodePort:                 kafka  32608/TCP
+Endpoints:                10.244.4.22:9092,10.244.4.24:9092,10.244.4.23:9092
+Session Affinity:         None
+External Traffic Policy:  Local
+Internal Traffic Policy:  Cluster
+Events:                   <none>
 ----
 
-Then, create a port-forward for the Kafka Broker:
+The output shows that there are three endpoints serviced here.
+They correspond to the three broker pods belonging to the Kafka cluster.
+
+Then, create a port-forward on this service:
 
 ----
 include::example$getting_started/getting_started.sh[tag=port-forwarding]
 ----
 
-Create a file containing some data:
+Now, create a new topic called `test-data-topic`:
 
 ----
-include::example$getting_started/getting_started.sh[tag=kcat-create-data]
+include::example$getting_started/getting_started.sh[tag=create-topic]
 ----
 
-Write that data:
+Use the Kafka performance producer script to send a couple of messages to the topic previously created:
 
 ----
-include::example$getting_started/getting_started.sh[tag=kcat-write-data]
+include::example$getting_started/getting_started.sh[tag=write-data]
 ----
 
-Read that data:
+The output should contain the following line:
 
 ----
-include::example$getting_started/getting_started.sh[tag=kcat-read-data]
+5 records sent, 1.138434 records/sec (0.00 MB/sec), 83.40 ms avg latency, 395.00 ms max latency, 3 ms 50th, 395 ms 95th, 395 ms 99th, 395 ms 99.9th.
 ----
 
-Check the content:
+This confirms that there were five messages sent to the topic and it also displays performance timers.
+We are not interested in any performance indicators but appreciate the fact that there were five unique messages that we consume later.
+
+Now let's consume the messages from above:
 
 ----
-include::example$getting_started/getting_started.sh[tag=kcat-check-data]
+include::example$getting_started/getting_started.sh[tag=read-data]
 ----
 
-And clean up:
+The consumer should print the messages in between logging statements
 
 ----
-include::example$getting_started/getting_started.sh[tag=kcat-cleanup-data]
+0
+1
+2
+3
+4
 ----
 
 You successfully created a Kafka cluster and produced and consumed data.

docs/modules/kafka/pages/getting_started/index.adoc

@@ -11,7 +11,6 @@ You need:
 * a Kubernetes cluster
 * kubectl
 * optional: Helm
-* https://github.com/edenhill/kcat#install[kcat] for testing
 
 Resource sizing depends on cluster type(s), usage and scope, but as a starting point a minimum of the following resources is recommended for this operator:
 

docs/modules/kafka/pages/index.adoc

@@ -21,7 +21,7 @@ It is commonly used for real-time data processing, data ingestion, event streami
 
 == Getting started
 
-Follow the xref:kafka:getting_started/index.adoc[] which guides you through installing The Stackable Kafka and ZooKeeper operators, setting up ZooKeeper and Kafka and testing your Kafka using `kcat`.
+Follow the xref:kafka:getting_started/index.adoc[] which guides you through installing The Stackable Kafka and ZooKeeper operators, setting up ZooKeeper and Kafka and testing your Kafka installation.
 
 == Resources