The working cycle of Kubernetes and its components involves the following steps:
- A user or application submits a request to the Kubernetes API server to create or modify a resource (e.g. a pod, a service, a deployment).
- The API server validates the request and stores it in etcd, the distributed key-value store that stores the configuration data of the cluster.
- The kube-controller-manager watches the etcd store for changes and updates the state of the cluster to reflect the desired state.
- The kube-scheduler receives a notification from the API server about a new pod that needs to be scheduled. It uses a scheduling algorithm to determine the best placement for the pod based on resource availability and constraints.
- The kube-scheduler sends a command to the API server to create the pod on the chosen worker node.
- The kubelet on the worker node receives the command and pulls the required container images from the container registry. It then starts the containers and runs them in a container runtime (e.g. Docker, containerd).
- The kubelet communicates with the master nodes to report the status of the pods and the node, and to receive updates and commands.
- If the state of the cluster or the resources in the cluster changes (e.g. due to a scale-up or scale-down event, a failure, or a rolling update), the kube-controller-manager and the kube-scheduler work together to ensure that the desired state is reflected in the actual state.
This is a general overview of the working cycle of Kubernetes and its components. The specific steps and interactions may vary depending on the specific resources and actions being performed and the configuration