Kubernetes Getting Started

Brief introduction
It is a new, container-based, distributed solution that solves the problem of load balancing and deployment in traditional system architectures based on a powerful automation mechanism, thus saving 30% development costs, followed by a complete clustering capability,

Including service registration, service discovery, fault detection and repair, service rolling upgrade, online expansion, health monitoring and other capabilities. Using Kubernetes can be a great way for developers to be more focused on business implementations while embracing a microservices architecture

Architecture

Basic concepts and terminology

1 , master cluster's control node.

Each kubernetes cluster needs to have a master node responsible for the management and control of the entire cluster. The Mater node includes a set of key processes:

• Kube-apiserver resources to delete and change the entrance of the operation, the doorman
• Kube-controller-manage Automation Control Center for all resources, major
• Kube-schedule is responsible for the scheduling of resources, control room

2 , node cluster's load nodes

Each node is assigned a certain workload (container) by master, and when node stops running, master dispatches the container to the other Node,node nodes including a set of critical processes:

• Kubelet responsible for the creation of pod corresponding container, start-Stop task
• Kube-proxy for service communication and load balancing
• Docker engine Docker engines are responsible for the creation and management of native containers

Common commands

View cluster Nodes

Kubectl Get Nodes

View node Details

Kubectl describe node xxx

3 , pod resource call base unit

Each pod contains a root container (pause) container and several other business containers, where the state of the root container represents the state of the container as a whole, and the business container shares the IP of the Pause container and the volumn it hangs on. Each pod in the cluster is assigned a unique IP, called the pod IP, and multiple containers in a pod share the pod IP address.

Pod A container stops, k8s detects and restarts all containers in the pod, so it fits in a pod to hold a business-related container

(1) The number of copies of the Replication Controller (RC) meets expectations at any time

The RC definition includes the following sections:

• • Number of replicas expected by pod
  • Label Selector for filtering the target pod
  • Create a new copy ' when the number of replicas is less than expected

Example: Defines a copy of tier:frontend in a kubenetes cluster with only one

(2) Replication Set (RS) Next-generation RC

The difference with RC is that RS supports the label Selector of the collection type, while RC supports only the equation-based label Selector. Other feature types.

(3) Label and label Selector

Label and label selector Concepts, Kubernetes can set the Key=value form of a label for the corresponding resource (pod,rc,service,deployment), which is simply understood as classification. At the same time, label selector can be managed according to the specified label and resource. For example, a service can load-balance a pod with a corresponding label based on the label selector. Label selector is divided into equation form (env=test) and set form (env not In[test,dev])

(4) Deployment increase the control and statistics of service start-up status on the basis of RS

An upgrade was made on the basis of RC to better solve the service orchestration problem. You can know the "progress of the deployment" of the current pod

Common commands

Create deployment

Kubectl create-f Tomcat-deployment.yaml

View Information '

Kubectl Get deployments

(5) Service Kubernetes the core resource object, POD RC RS, and other resource objects are all services provided for the service

kubernetes Every service inside is what we call microservices.

• • RC's role is to ensure service capabilities and service quality is always in the expected Biaozhun
  • Service and backend replica clusters are load balanced via label selector

Once the service is created, Kubernetes automatically assigns it an available cluster IP and does not change throughout the service's lifetime, and service name and services IP DNS mappings resolve the problem

Common commands

View Service

Kubectl Get Svc-n XXX

Create service

Kubectl create-f XXX

Kubernetes Getting Started