Node master is in charge of maintaining the desired state of the cluster and controlling the applications that are running and the containerized images that are used. To do this, the master node executes the following processes:
- etcd: Etcd is a database of type (key, value) that is used to maintain the global configuration of the cluster.
- Kube-apiserver:nodes master expose an API that is used to nodes working and clients of the cluster to communicate.
- kube-scheduler: it is the Kubernetes component in charge of deciding on which node a certain container runs.
- kube-controller-manager: it is in charge of executing the different controllers. A “controller” is in charge of ensuring that the desired state of the application and the cluster is met at all times (eg, that there are 5 instances of a given container at all times).
In the absence of a master node, the cluster would not be able to perform the previously stated functions, so the Kubernetes functions would be greatly affected.