Add Kafka escapeHeaders documentation (#4332)

* Add Kafka escapeHeaders documentation

Signed-off-by: Anton Troshin <[email protected]>

* update the escapeHeaders setting docs

Signed-off-by: Anton Troshin <[email protected]>

* review fixes

Signed-off-by: Anton Troshin <[email protected]>

---------

Signed-off-by: Anton Troshin <[email protected]>
Co-authored-by: Yaron Schneider <[email protected]>

daprdocs/content/en/reference/components-reference/supported-bindings/kafka.md

@@ -63,6 +63,8 @@ spec:
     value: true
   - name: schemaLatestVersionCacheTTL # Optional. When using Schema Registry Avro serialization/deserialization. The TTL for schema caching when publishing a message with latest schema available.
     value: 5m
+  - name: escapeHeaders # Optional.
+    value: false
 ```
 
 ## Spec metadata fields
@@ -99,6 +101,7 @@ spec:
 | `consumerFetchDefault` | N | Input/Output | The default number of message bytes to fetch from the broker in each request. Default is `"1048576"` bytes. | `"2097152"` |
 | `heartbeatInterval` | N | Input | The interval between heartbeats to the consumer coordinator. At most, the value should be set to a 1/3 of the `sessionTimeout` value. Defaults to `"3s"`. | `"5s"` |
 | `sessionTimeout` | N | Input | The timeout used to detect client failures when using Kafka’s group management facility. If the broker fails to receive any heartbeats from the consumer before the expiration of this session timeout, then the consumer is removed and initiates a rebalance. Defaults to `"10s"`. | `"20s"` |
+| `escapeHeaders` | N | Input | Enables URL escaping of the message header values received by the consumer. Allows receiving content with special characters that are usually not allowed in HTTP headers. Default is `false`. | `true` |
 
 #### Note
 The metadata `version` must be set to `1.0.0` when using Azure EventHubs with Kafka.

daprdocs/content/en/reference/components-reference/supported-pubsub/setup-apache-kafka.md

@@ -63,6 +63,8 @@ spec:
     value: true
   - name: schemaLatestVersionCacheTTL # Optional. When using Schema Registry Avro serialization/deserialization. The TTL for schema caching when publishing a message with latest schema available.
     value: 5m
+  - name: escapeHeaders # Optional.
+    value: false
 
 ```
 
@@ -112,6 +114,7 @@ spec:
 | consumerFetchDefault | N | The default number of message bytes to fetch from the broker in each request. Default is `"1048576"` bytes. | `"2097152"` |
 | heartbeatInterval | N | The interval between heartbeats to the consumer coordinator. At most, the value should be set to a 1/3 of the `sessionTimeout` value. Defaults to "3s". | `"5s"` |
 | sessionTimeout | N | The timeout used to detect client failures when using Kafka’s group management facility. If the broker fails to receive any heartbeats from the consumer before the expiration of this session timeout, then the consumer is removed and initiates a rebalance. Defaults to "10s". | `"20s"` |
+| escapeHeaders | N | Enables URL escaping of the message header values received by the consumer. Allows receiving content with special characters that are usually not allowed in HTTP headers. Default is `false`. | `true` |
 
 The `secretKeyRef` above is referencing  a [kubernetes secrets store]({{< ref kubernetes-secret-store.md >}}) to access the tls information. Visit [here]({{< ref setup-secret-store.md >}}) to learn more about how to configure a secret store component.
 
@@ -485,6 +488,39 @@ curl -X POST http://localhost:3500/v1.0/publish/myKafka/myTopic?metadata.correla
       }'
 ```
 
+## Receiving message headers with special characters
+
+The consumer application may be required to receive message headers that include special characters, which may cause HTTP protocol validation errors. 
+HTTP header values must follow specifications, making some characters not allowed. [Learn more about the protocols](https://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2).
+In this case, you can enable `escapeHeaders` configuration setting, which uses URL escaping to encode header values on the consumer side.
+
+{{% alert title="Note" color="primary" %}}
+When using this setting, the received message headers are URL escaped, and you need to URL "un-escape" it to get the original value.
+{{% /alert %}}
+
+Set `escapeHeaders` to `true` to URL escape.
+
+```yaml
+apiVersion: dapr.io/v1alpha1
+kind: Component
+metadata:
+  name: kafka-pubsub-escape-headers
+spec:
+  type: pubsub.kafka
+  version: v1
+  metadata:
+  - name: brokers # Required. Kafka broker connection setting
+    value: "dapr-kafka.myapp.svc.cluster.local:9092"
+  - name: consumerGroup # Optional. Used for input bindings.
+    value: "group1"
+  - name: clientID # Optional. Used as client tracing ID by Kafka brokers.
+    value: "my-dapr-app-id"
+  - name: authType # Required.
+    value: "none"
+  - name: escapeHeaders
+    value: "true"
+```
+
 ## Avro Schema Registry serialization/deserialization
 You can configure pub/sub to publish or consume data encoded using [Avro binary serialization](https://avro.apache.org/docs/), leveraging an [Apache Schema Registry](https://developer.confluent.io/courses/apache-kafka/schema-registry/) (for example, [Confluent Schema Registry](https://developer.confluent.io/courses/apache-kafka/schema-registry/), [Apicurio](https://www.apicur.io/registry/)).
 
@@ -597,6 +633,7 @@ To run Kafka on Kubernetes, you can use any Kafka operator, such as [Strimzi](ht
 
 {{< /tabs >}}
 
+
 ## Related links
 - [Basic schema for a Dapr component]({{< ref component-schema >}})
 - Read [this guide]({{< ref "howto-publish-subscribe.md##step-1-setup-the-pubsub-component" >}}) for instructions on configuring pub/sub components