Basic Concept

Master

A physical machine. It is using to monitor and dispatch to each node to work. The master is the controller.

Node

A node can be a virtual or physical machine. A node is a worker

Pod

  • A pod is the smallest unit in K8S. A pod is a container of containers.
  • A pod contains can container many containers.
  • A pod is a process.
  • Each pod has its own IP address.
  • Each pod can communicate, but the communication has to go via kube-proxy.
  • Pause is a root container in the pod.
  • Pod should contain a complete module per container.
  • You can use the analogy that each pod is a virtual machine.
  • All the communication should go through the pause between it goes out the pod

    Label

    Label is a description tag of a pod.

    Replication Controller

    It is used to replicate, delete, add new pods. It monitors the system has enough pods between nodes.

    Service

    Service is a logic group. Usually, the same services are put into the same pod. E.g Backend services are grouped into one pod and frontend services are grouped in another pod.