SAP Updated C_KYMD_01 Exam Questions and Answers by harper

 A Kubernetes cluster is a set of machines, either physical or virtual, that run Kubernetes agents and are managed by the control plane1. A cluster consists of at least one control plane node and one or more worker nodes. The control plane node runs the processes that control the cluster, such as the API server, the scheduler, and the controller manager. The worker nodes run the pods that host the containerized applications. Machines can be grouped into node pools, which are sets of machines that share the same configuration, such as size, type, or labels2. References: 1(https://kubernetes.io/docs/concepts/overview/components/),  2(https://www.redhat.com/en/topics/containers/what-is-a-kubernetes-cluster)

• Use kubectl apply to create or update resources from a file or stdin. This command does a three-way diff between the previous configuration, the input configuration, and the current configuration of the resource, and then applies the changes.
• Use kubectl patch to update Kubernetes API objects in place. Do a strategic merge patch or a JSON merge patch.
• Use kubectl replace to delete and re-create the resource. You can use this command to update immutable fields of a resource, such as its kind or name.

References:

• Manage Kubernetes Objects
• Command line tool (kubectl)
• kubectl Quick Reference

Kyma Eventing simplifies the process of publishing and subscribing to events in the cluster. Publishing events means sending information about a change in the state of the application or the system to the Eventing backend. Subscribing to events means registering interest for a specific event type from a specific source. Kyma Eventing allows users to publish events by sending HTTP requests to the Event Publisher Proxy component, which validates and forwards the events to the NATS backend. Kyma Eventing also allows users to subscribe to events by creating Subscription custom resources that specify the event source, type, and the HTTP endpoint of the service that will receive the events. Kyma Eventing handles the delivery of the events from the NATS backend to the subscribers with the help of the Eventing Controller and the Eventing Dispatcher components. References: https://kyma-project.io/

https://blogs.sap.com/2021/06/15/in-cluster-eventing-in-sap-btp-kyma-runtime/

The API Gateway is a component that enables exposing and securing services outside the Kyma cluster using the APIRule custom resource (CR)1. The API Gateway has the following characteristics:

• It is the central point of contact for all external traffic that enters the Kyma cluster. The API Gateway is a custom-configured Istio Ingress Gateway that is installed in the kyma-system namespace called kyma-gateway2. The kyma-gateway acts as a reverse proxy that routes the incoming requests to the appropriate services based on the host name and the path specified in the APIRule CR3.
• It uses Envoy Proxy to handle traffic and forward it to the correct service. The API Gateway is based on the Istio Gateway, which is a load balancer that operates at the edge of the mesh and enables ingress and egress traffic for the cluster. The Istio Gateway is implemented by a pod that runs an Envoy Proxy container, which is responsible for receiving and forwarding the traffic according to the Istio routing rules.

References:

• 1: Kyma / API Gateway v2
• 2: Using the API Gateway to Expose Services - SAP Learning
• 3: SAP BTP, Kyma Runtime API Gateway future architecture based on Istio | SAP Blogs
• [4]: Istio / Gateway
• [5]: Istio / Envoy