Kubernetes Important Concept Understanding

Kubernetes Important Concept Understanding

Kubernetes is currently the most mainstream container orchestration tool, the next generation of distributed architecture of the king. 2018 Kubernetes The first version 1.10 has been released. Here's a look at some of the basic concepts of kubernetes.

The kubernetes divides the machines in the cluster into master nodes and work nodes (node). The master node runs a set of processes Kube-apiserver, Kube-controller-manager, and Kube-schedule, as well as ETCD services, that manage the cluster. node as a working node in the cluster, running a real application, the smallest running unit kubernetes managed on node is Pod,node running the Kubelet, Kube-proxy, Docker engine service process. Such as:

Available: Images from the Web

Master node : Control node of the cluster
Kubernetes API Server (kube-aoiserver): provides the HTTP rest interface of the key service process, is the Kubernetes of all the resources of the increase, deletion, change, check and other operations of the only entry, is also a cluster control of the entry process.
Kube-controller-manager: The Automation Control center of all resources in kubernetes, can be understood as the "big manager" of the resource object.
Kube-schedule: Responsible for the process of resource scheduling (pod scheduling), the equivalent of the bus company's "control room"
ETCD: The data for all resource objects inside the kubernetes are saved in ETCD.

node Nodes: Node nodes can be either a physical machine or a virtual machine. When a node goes down, the work on it is automatically transferred to the other node by master.
Kubelet: Responsible for the pod corresponding to the creation of containers, starting and stopping tasks. At the same time, work closely with master node to realize the basic function of cluster management.
Kube-proxy: An important component for implementing communication and load balancing mechanisms for kubernetes service.
Docker Engine (Docker):D Ocker engine, responsible for the creation and management of native containers.

Pod concept
Pod is the most important and basic concept of kubernetes, and each pod has a special pause container called the "root container". The mirror corresponding to the Pause container is part of the Kubernetes platform, with the exception of the Pause container, where each pod contains one or more tightly related user business containers.
All resource objects in the kubernetes can be defined or described in either YAML or JSON format, as shown in the definition of a pod:
Apiserver:v1
Kind:pod
Metadata
Name:myweb
Labels
Name:myweb
Spec
Containers
-name:myweb
Image:kubeguide/tomcat-app:v1
Ports
-containterport:8080
Env:
-name:mysql_service_host
Value: ' MySQL '
-name:mysql_service_port
Value: ' 3306 '

Kind for pod indicates that this is a pod definition, the Name property in metadata is the name of the pod, and Metdata can also define the label of the resource object, which declares that MyWeb has a name=myweb label (label). The definition of the container contained in the pod is declared in the Spec section, where a container named MyWeb, corresponding to the mirror KUBEGUIDE/TOMCAT-APP:V1, is injected with mysql_service_host= ' MySQL ' and mysql_service_port= ' 3306 ' environment variables (env keyword) and start the container process on port 8080 (containerport).

The above is some of the most basic concepts in kubernetes, the detailed content will continue to be updated in the future!

Kubernetes Important Concept Understanding