Concepts and architecture

Kubernetes provides the foundation of a Konvoy cluster. Because of this fundamental relationship, you should be familiar with a few key concepts and terms. The topics in this section provide a brief overview of the native Kubernetes architecture, the core components of the Konvoy cluster, and a simplified view of the Konvoy architecture and the operational workflow for a Konvoy cluster.

The following diagram provides a simplified architectural overview to help you visualize the key components of the cluster:

Figure 1 - Architectural overview

Master components for the Kubernetes control plane

The native Kubernetes cluster consists of master components that provide the cluster’s control plane and worker nodes that run users’ containers and maintain the runtime environment.

The master components in your cluster manage activities that affect the cluster as a whole. For example, master components handle scheduling and changes to workload requirements in response to cluster events.

Technically, you can deploy master components on any machine in the cluster. By default, however, master components are only deployed on the machines you designate as control plane servers.

The master components in a native Kubernetes cluster include the following:

• kube-apiserver exposes the Kubernetes application programming interface (API) and provides a web-based front-end for the Kubernetes control plane.
• etcd provides a key value store that you can use to store all Kubernetes cluster data.
• kube-scheduler monitors the cluster to detect newly-created pods that have no node assigned, and selects a node for those pods to run on.
• kube-controller-manager manages the collection of individual controller processes as a single binary.

The controllers include:

• A node controller that keeps track of node status and responds if nodes go down.
• A replication controller that maintains the correct number of pods for every replication controller object in the system.
• An endpoints controller that populates endpoints.
• A service account and token controller that creates default accounts and access tokens for new service namespaces.
• cloud-controller-manager runs controllers that interact with the underlying cloud providers.

For more information about any of the master components or Kubernetes control plane, see the Kubernetes documentation.

Worker nodes

Worker nodes maintain running pods and provide the runtime environment for the native Kubernetes cluster. Each work node includes the following key components:

• The kubelet agent runs on each node in the cluster to ensure that the containers created by Kubernetes for a pod are running and in a healthy state.
• The kube-proxy serves as a network proxy that runs on each node in the cluster to enforce network routing and connection forwarding rules.
• The Kubernetes container runtime manages any supported type of container, such as Docker or containerd, that runs on the cluster.

Platform service addons

The native Kubernetes cluster supports a set of addons. Addons use Kubernetes resources to implement specific cluster-level features; because they provide cluster-level features, addons are defined in the kube-system namespace.

Konvoy supplements the native Kubernetes cluster by providing a predefined and pre-configured set of addons. Because this predefined set of addons provides critical features for managing a Kubernetes cluster in a production environment, the default set of addons is identified as Konvoy platform services which are a key part of delivering an opinionated Kubernetes solution.

Related information

For information on related topics or procedures, refer to the following:

• Kubernetes Base Addons