Master Node & its Components
- The main machine that controls the nodes.
- Managing & controlling & orchestrating of the worker nodes.
- Make global decisions about cluster, like scheduling.
- Detecting and responding to cluster events, like starting up a new pod.
.:: Kube-APIServer ::.
- Everything in kubernetes cluster will connect and talk to this API Server.
- It is the front-end tools for sending kubeconfigs trough kubectl CLI.
- API server validates & configures required data for worker nodes.
- Communicate with other libraries & components using RESTfull interface
.:: etcd or Cluster-Store ::.
- It is stands for “/etc distributed”.
- A place for storing config files of clusters there. (Accessible only by API Server)
- It is a key-value based storage for manage critical information.
- Highly recommended to have a backup plan for etcd in a cluster.
.:: Kube-Scheduler ::.
- Decide where to start the workload, on which node should it start the application.
- Choosing a node for newly created pods on kubernetes.
- individual & collective resource requirements, hardware/software/policy constraints, affinity & anti-affinity specifications, data locality & inter-workload interference.
.:: Kube-Controller-Manager ::.
- There are some controllers here that each controller is a separate process, but they are all compiled into a single binary and run in a single process.
- It includes: Node/Replication/Endpoints/Service-Account/Token Controller
