feat: add the necessary portion of the doc from the old doc

docs/eventing/configuration/broker-configuration.md

@@ -85,6 +85,9 @@ clusterDefault:
 
 This configuration sets `MTChannelBasedBroker` as the default Broker class for the entire cluster and specifies its configuration.
 
+!!! note
+    Be aware that different Broker classes usually require different configuration ConfigMaps. See the configuration options of the different [Broker implementations](../brokers/broker-types/README.md) on how their referenced ConfigMaps have to look like (e.g. for [MTChannelBasedBroker](../brokers/broker-types/channel-based-broker/README.md#configuration-configmap) or [Knative Broker for Apache Kafka](../brokers/broker-types/kafka-broker/README.md#configure-a-kafka-broker)).
+
 ## Configuring Namespace-specific Defaults
 
 To set default Broker classes and configurations for specific namespaces:
@@ -111,6 +114,240 @@ namespaceDefaults:
 
 This configuration sets different default Broker classes and configurations for `namespace-1` and `namespace-2`.
 
+
+## Configuring delivery spec defaults
+
+You can configure default event delivery parameters for Brokers that are applied in cases where an event fails to be delivered:
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: config-br-defaults
+  namespace: knative-eventing
+data:
+  # Configures the default for any Broker that does not specify a spec.config or Broker class.
+  default-br-config: |
+    clusterDefault:
+      brokerClass: MTChannelBasedBroker
+      brokerClasses:
+        MTChannelBasedBroker:
+          apiVersion: v1
+          kind: ConfigMap
+          name: kafka-channel
+          namespace: knative-eventing
+          delivery:
+            retry: 10
+            backoffDelay: PT0.2S
+            backoffPolicy: exponential
+    namespaceDefaults:
+      namespace-1:
+        brokerClass: MTChannelBasedBroker
+        brokerClasses:
+          MTChannelBasedBroker:
+            apiVersion: v1
+            kind: ConfigMap
+            name: config-br-default-channel
+            namespace: knative-eventing
+            delivery:
+              deadLetterSink:
+                ref:
+                  kind: Service
+                  namespace: example-namespace
+                  name: example-service
+                  apiVersion: v1
+                uri: example-uri
+              retry: 10
+              backoffPolicy: exponential
+              backoffDelay: "PT0.2S"
+```
+
+### Dead letter sink
+
+You can configure the `deadLetterSink` delivery parameter so that if an event fails to be delivered it is sent to the specified event sink.
+
+### Retries
+
+You can set a minimum number of times that the delivery must be retried before the event is sent to the dead letter sink, by configuring the `retry` delivery parameter with an integer value.
+
+### Back off delay
+
+You can set the `backoffDelay` delivery parameter to specify the time delay before an event delivery retry is attempted after a failure. The duration of the `backoffDelay` parameter is specified using the ISO 8601 format.
+
+### Back off policy
+
+The `backoffPolicy` delivery parameter can be used to specify the retry back off policy. The policy can be specified as either linear or exponential. When using the linear back off policy, the back off delay is the time interval specified between retries. When using the exponential backoff policy, the back off delay is equal to `backoffDelay*2^<numberOfRetries>`.
+
+## Integrating Istio with Knative Brokers
+
+### Protect a Knative Broker by using JSON Web Token (JWT) and Istio
+
+#### Prerequisites
+
+- You have installed Knative Eventing.
+- You have installed Istio.
+
+#### Procedure
+
+1. Label the `knative-eventing` namespace, so that Istio can handle JWT-based user authentication, by running the command:
+
+    ```bash
+    kubectl label namespace knative-eventing istio-injection=enabled
+    ```
+
+1. Restart the broker ingress pod, so that the `istio-proxy` container can be injected as a sidecar, by running the command:
+
+    ```bash
+    kubectl delete pod <broker-ingress-pod-name> -n knative-eventing
+    ```
+
+   Where `<broker-ingress-pod-name>` is the name of your Broker ingress pod.
+
+   The pod now has two containers:
+
+    ```{ .bash .no-copy }
+    knative-eventing     <broker-ingress-pod-name>           2/2     Running   1              175m
+    ```
+
+1. Create a broker, then use get the URL of your Broker by running the command:
+
+    ```bash
+    kubectl get broker <broker-name>
+    ```
+
+   Where `<broker-name>` is the name of your Broker.
+
+   Example output:
+
+    ```{ .bash .no-copy }
+    NAMESPACE   NAME        URL                                                                          AGE   READY   REASON
+    default     my-broker   http://broker-ingress.knative-eventing.svc.cluster.local/default/my-broker   6s    True
+    ```
+
+1. Start a `curl` pod by running the following command:
+
+    ```bash
+    kubectl -n default run curl --image=radial/busyboxplus:curl -i --tty
+    ```
+
+1. Send a CloudEvent with an HTTP POST against the Broker URL by running the following command:
+
+    ```bash
+    curl -X POST -v \
+    -H "content-type: application/json"  \
+    -H "ce-specversion: 1.0"  \
+    -H "ce-source: my/curl/command"  \
+    -H "ce-type: my.demo.event"  \
+    -H "ce-id: 0815"  \
+    -d '{"value":"Hello Knative"}' \
+    <broker-URL>
+    ```
+
+   Where `<broker-URL>` is the URL of your Broker. For example:
+
+    ```{ .bash .no-copy }
+    curl -X POST -v \
+    -H "content-type: application/json"  \
+    -H "ce-specversion: 1.0"  \
+    -H "ce-source: my/curl/command"  \
+    -H "ce-type: my.demo.event"  \
+    -H "ce-id: 0815"  \
+    -d '{"value":"Hello Knative"}' \
+    http://broker-ingress.knative-eventing.svc.cluster.local/default/my-broker
+    ```
+
+1. You will receive a `202` HTTP response code, that the broker did accept the request:
+
+    ```{ .bash .no-copy }
+    ...
+    * Mark bundle as not supporting multiuse
+    < HTTP/1.1 202 Accepted
+    < allow: POST, OPTIONS
+    < date: Tue, 15 Mar 2022 13:37:57 GMT
+    < content-length: 0
+    < x-envoy-upstream-service-time: 79
+    < server: istio-envoy
+    < x-envoy-decorator-operation: broker-ingress.knative-eventing.svc.cluster.local:80/*
+    ```
+
+1. Apply a `AuthorizationPolicy` object in the `knative-eventing` namespace to describe that the path to the Broker is restricted to a given user:
+
+    ```yaml
+    apiVersion: security.istio.io/v1beta1
+    kind: AuthorizationPolicy
+    metadata:
+      name: require-jwt
+      namespace: knative-eventing
+    spec:
+      action: ALLOW
+      rules:
+      - from:
+        - source:
+           requestPrincipals: ["testing@secure.istio.io/testing@secure.istio.io"]
+        to:
+        - operation:
+            methods: ["POST"]
+            paths: ["/default/my-broker"]
+    ```
+
+1. Create a `RequestAuthentication` object for the user `requestPrincipal` in the `istio-system` namespace:
+
+    ```yaml
+    apiVersion: security.istio.io/v1beta1
+    kind: RequestAuthentication
+    metadata:
+      name: "jwt-example"
+      namespace: istio-system
+    spec:
+      jwtRules:
+      - issuer: "testing@secure.istio.io"
+        jwksUri: "https://raw.githubusercontent.com/istio/istio/release-1.13/security/tools/jwt/samples/jwks.json"
+    ```
+
+1. Now retrying the `curl` command results in a `403 - Forbidden` response code from the server:
+
+    ```{ .bash .no-copy }
+    ...
+    * Mark bundle as not supporting multiuse
+    < HTTP/1.1 403 Forbidden
+    < content-length: 19
+    < content-type: text/plain
+    < date: Tue, 15 Mar 2022 13:47:53 GMT
+    < server: istio-envoy
+    < connection: close
+    < x-envoy-decorator-operation: broker-ingress.knative-eventing.svc.cluster.local:80/*
+    ```
+
+1. To access the Broker, add the Bearer JSON Web Token as part of the request:
+
+    ```bash
+    TOKEN=$(curl https://raw.githubusercontent.com/istio/istio/release-1.13/security/tools/jwt/samples/demo.jwt -s)
+
+    curl -X POST -v \
+    -H "content-type: application/json"  \
+    -H "Authorization: Bearer ${TOKEN}"  \
+    -H "ce-specversion: 1.0"  \
+    -H "ce-source: my/curl/command"  \
+    -H "ce-type: my.demo.event"  \
+    -H "ce-id: 0815"  \
+    -d '{"value":"Hello Knative"}' \
+    <broker-URL>
+    ```
+
+   The server now responds with a `202` response code, indicating that it has accepted the HTTP request:
+
+    ```{ .bash .no-copy }
+    * Mark bundle as not supporting multiuse
+    < HTTP/1.1 202 Accepted
+    < allow: POST, OPTIONS
+    < date: Tue, 15 Mar 2022 14:05:09 GMT
+    < content-length: 0
+    < x-envoy-upstream-service-time: 40
+    < server: istio-envoy
+    < x-envoy-decorator-operation: broker-ingress.knative-eventing.svc.cluster.local:80/*
+    ```
+
+
 ## Best Practices and Considerations
 
 1. **Consistency**: Ensure that the `brokerClass` specified matches a key in the `brokerClasses` map to maintain consistency.