Introducing Kubernetes runtime components
A Kubernetes cluster contains two types of nodes: master nodes and worker nodes. Master nodes manage the cluster, while the main purpose of worker nodes is to run the actual workload – for example, the containers we deploy in the cluster. Kubernetes is built up of a number of runtime components. The most important components are as follows:
- There are components that run on master nodes, constituting the control plane:
- API server, the entry point to the control plane. This exposes a RESTful API, which, for example, the Kubernetes CLI tool known as kubectl uses.
- etcd, a highly available and distributed key/value store, used as a database for all cluster data.
- A controller manager, which contains a number of controllers that continuously evaluate the desired state versus the current state for the objects defined in the etcd database. Whenever the desired or current state changes, a controller that...
