Added kafka features config map to kafka broker docs (#5622)

* Added kafka features config map to kafka broker docs

* Update docs/eventing/brokers/broker-types/kafka-broker/README.md

Co-authored-by: Leo Li <leoli@redhat.com>

* Update docs/eventing/brokers/broker-types/kafka-broker/README.md

Co-authored-by: Leo Li <leoli@redhat.com>

* Update docs/eventing/brokers/broker-types/kafka-broker/README.md

Co-authored-by: Leo Li <leoli@redhat.com>

* Update docs/eventing/brokers/broker-types/kafka-broker/README.md

Co-authored-by: Leo Li <leoli@redhat.com>

* Update docs/eventing/brokers/broker-types/kafka-broker/README.md

Co-authored-by: Leo Li <leoli@redhat.com>

* Update docs/eventing/brokers/broker-types/kafka-broker/README.md

Co-authored-by: Pierangelo Di Pilato <pierangelodipilato@gmail.com>

* Moved kafka features config info to new page

* Apply suggestions from code review

Co-authored-by: Pierangelo Di Pilato <pierangelodipilato@gmail.com>

* Follow example from serving for documenting configmap keys

Signed-off-by: Calum Murray <cmurray@redhat.com>

* Fix macro

Signed-off-by: Calum Murray <cmurray@redhat.com>

---------

Signed-off-by: Calum Murray <cmurray@redhat.com>
Co-authored-by: Leo Li <leoli@redhat.com>
Co-authored-by: Pierangelo Di Pilato <pierangelodipilato@gmail.com>

config/nav.yml

@@ -191,7 +191,9 @@ nav:
             - Available Broker types: eventing/brokers/broker-types/README.md
             # add default IMC broker page, page explaining broker types
             - Channel based Broker: eventing/brokers/broker-types/channel-based-broker/README.md
-            - Apache Kafka: eventing/brokers/broker-types/kafka-broker/README.md
+            - Apache Kafka: 
+              - About Apache Kafka Broker: eventing/brokers/broker-types/kafka-broker/README.md
+              - Configuring Kafka features: eventing/brokers/broker-types/kafka-broker/configuring-kafka-features.md
             - RabbitMQ Broker: eventing/brokers/broker-types/rabbitmq-broker/README.md
           - Creating a Broker: eventing/brokers/create-broker.md
           - Developer configuration options: eventing/brokers/broker-developer-config-options.md

docs/eventing/brokers/broker-types/kafka-broker/README.md

@@ -6,7 +6,7 @@ Notable features are:
 
 - Control plane High Availability
 - Horizontally scalable data plane
-- [Extensively configurable](#kafka-producer-and-consumer-configurations)
+- [Extensively configurable](./configuring-kafka-features)
 - Ordered delivery of events based on [CloudEvents partitioning extension](https://github.com/cloudevents/spec/blob/v1.0.2/cloudevents/extensions/partitioning.md)
 - Support any Kafka version, see [compatibility matrix](https://cwiki.apache.org/confluence/display/KAFKA/Compatibility+Matrix)
 - Supports 2 [data plane modes](#data-plane-isolation-vs-shared-data-plane): data plane isolation per-namespace or shared data plane
@@ -440,7 +440,7 @@ Upon the creation of the first `Broker` with `KafkaNamespaced` class, the `kafka
 
 All the configuration mechanisms that are available for the `Kafka` Broker class are also available for the brokers with `KafkaNamespaced` class with these exceptions:
 
-* [Above](#kafka-producer-and-consumer-configurations) it is described how producer and consumer configurations is done by modifying the `config-kafka-broker-data-plane` configmap in the `knative-eventing` namespace. Since Kafka Broker controller propagates this configmap into the user namespace, currently there is no way to configure producer and consumer configurations per namespace. Any value set in the `config-kafka-broker-data-plane` `ConfigMap` in the `knative-eventing` namespace will be also used in the user namespace.
+* [This page](./configuring-kafka-features) describes how producer and consumer configurations is done by modifying the `config-kafka-broker-data-plane` configmap in the `knative-eventing` namespace. Since Kafka Broker controller propagates this configmap into the user namespace, currently there is no way to configure producer and consumer configurations per namespace. Any value set in the `config-kafka-broker-data-plane` `ConfigMap` in the `knative-eventing` namespace will be also used in the user namespace.
 * Because of the same propagation, it is also not possible to configure consumer offsets commit interval per namespace.
 * A few more configmaps are propagated: `config-tracing` and `kafka-config-logging`. This means, tracing and logging are also not configurable per namespace.
 * Similarly, the data plane deployments are propagated from the `knative-eventing` namespace to the user namespace. This means that the data plane deployments are not configurable per namespace and will be identical to the ones in the `knative-eventing` namespace.

docs/eventing/brokers/broker-types/kafka-broker/configuring-kafka-features.md

@@ -0,0 +1,70 @@
+# Configuring Kafka Features
+
+There are many different configuration options for how Knative Eventing and the Knaitve Broker for Apache Kafka interact with the Apache Kafka clusters.
+
+## Configure Knative Eventing Kafka features
+
+There are various kafka features/default values the Knative Kafka Broker uses when interacting with Kafka.
+
+### Consumer Group ID for Triggers
+
+The `triggers.consumergroup.template` value determines the template used to generate the consumer group ID used by your triggers.
+
+* **Global key:** `triggers.consumergroup.template`
+* **Possible values:**: Any valid [go text/template](https://pkg.go.dev/text/template)
+* **Default:** `{% raw %}knative-trigger-{{ .Namespace }}-{{ .Name }}{% endraw %}`
+
+**Example:**
+
+=== "Global (ConfigMap)"
+    ```yaml
+    apiVersion: v1
+    kind: ConfigMap
+    metadata:
+      name: config-kafka-features
+      namespace: knative-eventing
+    data:
+      triggers.consumergroup.template: {% raw %}"knative-trigger-{{ .Namespace }}-{{ .Name }}"{% endraw %}
+    ```
+
+### Broker topic name template
+
+The `brokers.topic.template` values determines the template used to generate the Kafka topic names used by your brokers.
+
+* **Global Key:** `brokers.topic.template`
+* **Possible values:** Any valid [go text/template](https://pkg.go.dev/text/template)
+* **Default:** `{% raw %}knative-broker-{{ .Namespace }}-{{ .Name }}{% endraw %}`
+
+**Example:**
+
+=== "Global (ConfigMap)"
+    ```yaml
+    apiVersion: v1
+    kind: ConfigMap
+    metadata:
+      name: config-kafka-features
+      namespace: knative-eventing
+    data:
+      brokers.topic.template: {% raw %}"knative-broker-{{ .Namespace }}-{{ .Name }}"{% endraw %}
+    ```
+
+## Channel topic name template
+
+The `channels.topic.template` value determines the template used to generate the kafka topic names used by your channels.
+
+* **Global Key:** `channels.topic.template`
+* **Possible values:** Any valid [go text/template](https://pkg.go.dev/text/template)
+* **Default:** `{% raw %}messaging-kafka.{{ .Namespace }}.{{ .Name }}{% endraw %}`
+
+**Example:**
+
+=== "Global (ConfigMap)"
+    ```yaml
+    apiVersion: v1
+    kind: ConfigMap
+    metadata:
+      name: config-kafka-features
+      namespace: knative-eventing
+    data:
+      channels.topic.template: {% raw %}"messaging-kafka.{{ .Namespace }}.{{ .Name }}"{% endraw %}
+    ```