Example for Kafka TLS Authentication (#2473)

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add examples for kafka tls

* add example for kafka tls

* add example for kafka tls

docs/eventing/samples/kafka/source/README.md

@@ -124,8 +124,10 @@ You must ensure that you meet the [prerequisites listed in the Apache Kafka over
      name: kafka-source
    spec:
      consumerGroup: knative-group
-     bootstrapServers: my-cluster-kafka-bootstrap.kafka:9092 #note the kafka namespace
-     topics: knative-demo-topic
+     bootstrapServers:
+     - my-cluster-kafka-bootstrap.kafka:9092 # note the kafka namespace
+     topics:
+     - knative-demo-topic
      sink:
        ref:
          apiVersion: serving.knative.dev/v1
@@ -177,7 +179,6 @@ You must ensure that you meet the [prerequisites listed in the Apache Kafka over
 
    ```
    $ kubectl logs --selector='serving.knative.dev/service=event-display' -c user-container
-   ```
 
    ☁️ cloudevents.Event
    Validation: valid
@@ -195,7 +196,6 @@ Data,
        {
          "msg": "This is a test!"
        }
-
    ```
 
 ## Teardown Steps
@@ -226,7 +226,7 @@ customresourcedefinition.apiextensions.k8s.io "kafkasources.sources.knative.dev"
    deleted service "kafka-controller" deleted statefulset.apps
    "kafka-controller-manager" deleted
 
-````
+   ```
 4. (Optional) Remove the Apache Kafka Topic
 
    ```shell
@@ -247,9 +247,7 @@ You can specify the key deserializer among four types:
 * `float` for 32-bit & 64-bit floating points
 * `byte-array` for a Base64 encoded byte array
 
-To specify it, add the label `kafkasources.sources.knative.dev/key-type` to the
-`KafkaSource` definition like:
-
+To specify it, add the label `kafkasources.sources.knative.dev/key-type` to the `KafkaSource` definition like:
    ```yaml
    apiVersion: sources.knative.dev/v1alpha1
    kind: KafkaSource
@@ -259,11 +257,69 @@ metadata:
       kafkasources.sources.knative.dev/key-type: int
    spec:
     consumerGroup: knative-group
-  bootstrapServers: my-cluster-kafka-bootstrap.kafka:9092 #note the kafka namespace
-  topics: knative-demo-topic
+    bootstrapServers:
+    - my-cluster-kafka-bootstrap.kafka:9092 # note the kafka namespace
+    topics:
+    - knative-demo-topic
     sink:
       ref:
         apiVersion: serving.knative.dev/v1
         kind: Service
         name: event-display
    ```
+
+## Connecting to a TLS enabled Kafka broker
+
+The KafkaSource supports TLS and SASL authentication methods. For enabling TLS authentication, please have the below files
+
+* CA Certificate
+* Client Certificate and Key
+
+KafkaSource expects these files to be in pem format, if it is in other format like jks, please convert to pem.
+
+1. Create the certificate files as secrets in the namespace where KafkaSource is going to be set up
+   ```
+
+   $ kubectl create secret generic cacert --from-file=caroot.pem
+   secret/cacert created
+
+   $ kubectl create secret tls kafka-secret --cert=certificate.pem --key=key.pem
+   secret/key created
+
+
+   ```
+
+2. Apply the KafkaSource, change bootstrapServers and topics accordingly.
+   ```yaml
+   apiVersion: sources.knative.dev/v1alpha1
+   kind: KafkaSource
+   metadata:
+    name: kafka-source-with-tls
+   spec:
+    net:
+      tls:
+        enable: true
+        cert:
+          secretKeyRef:
+            key: tls.crt
+            name: kafka-secret
+        key:
+          secretKeyRef:
+            key: tls.key
+            name: kafka-secret
+        caCert:
+          secretKeyRef:
+            key: caroot.pem
+            name: cacert
+   consumerGroup: knative-group
+   bootstrapServers:
+   - my-secure-kafka-bootstrap.kafka:443
+   topics:
+   - knative-demo-topic
+   sink:
+     ref:
+       apiVersion: serving.knative.dev/v1
+       kind: Service
+       name: event-display
+   ```
+