官网入门教程

create a cluster

concept

集群图

Kubernetes 是一个生产级的开源平台，用于协调计算机集群内部和跨计算机集群的应用程序容器的分发(调度)和运行。？这句话不是很明白

K8s集群由两种资源组成：

• 一个master是集群的调度节点
• Nodes 是应用程序实际运行的工作节点

interactive learning

使用minikube创建集群
minikube version
minikube start
使用minikube 启动vm，并让k8s集群在vm上运行

kubectl version 查看集群版本
client version is the kubectl version
server version is the Kubernetes installed on the master

Client Version: version.Info{
Major:"1", Minor:"15", GitVersion:"v1.15.2",
GitCommit:"f6278300bebbb750328ac16ee6dd3aa7d3549568", 
GitTreeState:"clean", BuildDate:"2019-08-05T09:23:26Z", 
GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"
}
Server Version: version.Info{
Major:"1", Minor:"15", GitVersion:"v1.15.0", 
GitCommit:"e8462b5b5dc2584fdcd18e6bcfe9f1e4d970a529",
GitTreeState:"clean", BuildDate:"2019-06-19T16:32:14Z",
GoVersion:"go1.12.5", Compiler:"gc", Platform:"linux/amd64"
}

kubectl cluster-info to view the cluster details
kubectl get nodes

NAME       STATUS   ROLES    AGE   VERSION
minikube   Ready    master   10m   v1.15.0

show all nodes that can be used to host our applications

create a deployment

A Deployment is responsible for creating and updating instances of your application `·

kubectl run edgar --image=edgar --port=80
kubectl run deploymentName ImageAddress accessablePort

kubectl run ... performed few things:

• searched for a suitable node where an instance of the application could be run (we have only 1 available node)
• scheduled the application to run on that Node
• configured the cluster to reschedule the instance on a new Node when needed

  interactive learning

  explore your app

  pods、nodes

A Pod is a group of one or more application containers (such as Docker or rkt) and includes shared storage (volumes), IP address and information about how to run them.

_

troubleshooting
kubectl get kubectl describ kubectl logs kubectl exec

interactive learning

show the app in the terminal

pods are running in an isolated, private network.

1. open a new terminal and run the proxy. kubectl proxy
2. tab to the first terminal and then will et the Pod name and query.

export POD_NAME=$(kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}') echo Name of the Pod: $POD_NAME
output: Name of the Pod: kubernetes-bootcamp-5b48cfdcbd-rpg65

1. to visit application

curl http://localhost:8001/api/v1/namespaces/default/pods/$POD_NAME/proxy/

view the container logs
kubectl logs $POD_NAME

executing command on the container
list the environments variables
kubectl exec $POD_NAME env

start a bash session in the Pod’s container
kubectl exec -ti $POD_NAME bash

check the application is up
curl localhost:8080

to close your container connection type **exit**

using a service to expose your app

• Service
• Understand how labels and LabelSelector objects relate to a Service

• Expose an application outside a Kubernetes cluster using a Service

  concept

  Services can be exposed in different ways by specifying a type in the ServiceSpec

• ClusterIP (default)

• _NodePort. _Superset of ClusterIP.
• _LoadBalancer. _Superset of NodePort
• _ExternalName. _No proxy is used

Labels are key/value pairs attached to objects and can be used in any number of ways:

• Designate objects for development, test, and production
• Embed version tags
• Classify an object using tags

interactive learning

create a new service

list current services from the cluster
kubectl get services

to create a service and expose it to external traffic
kubectl expose deployment/kubernetes-bootcamp --type="NodePort" --port 8080

to get $NODE_PORT
export NODE_PORT=$(kubectl get services/kubernetes-bootcamp -o go-template='{{(index .spec.ports 0).nodePort}}')

test that the app is exposed outside of the cluster using curl
curl $(minikube ip):$NODE_PORT

using labels

to find the name of the label
kubectl describe deployment
labels: run=kubernetes-bootcamp

using label to query the Pod
kubectl get pods -l run=kubernetes-bootcamp

to apply a new label
label = key value
1 export POD_NAME=$(kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}')
2 kubectl label pod $POD_NAME app=v1

deleting a service

delete a service by target label
kubectl delete service -l run=kubernetes-bootcamp

confirm that the service is gone
kubectl get services

confirm that route is not exposed anymore
curl $(minikube ip):$NODE_PORT

confirm that the app is still running inside the pod
kubectl exec -ti $POD_NAME curl localhost:8080 suceess
We see here that the application is up. This is because the Deployment is managing the application. To shut down the application, you would need to delete the Deployment as well.

scale your app

Scaling a Deployment

before:

after

interactive learning

scale
kubectl scale deployments/kubernetes-bootcamp --replicas=2

load balancing
export NODE_PORT=$(kubectl get services/kubernetes-bootcamp -o go-template='{{(index .spec.ports 0).nodePort}}')

Execute the command multiple times. We hit a different Pod with every request
curl $(minikube ip):$NODE_PORT

update your app

• update

kubectl set image deploymentName newImage
kubectl set image deployments/kubernetes-bootcamp kubernetes-bootcamp=jocatalin/kubernetes-bootcamp:v2

• verify an update

way 1
curl $(minikube ip):$NODE_PORT

way 2
kubectl rollout status deployments/kubernetes-bootcamp

• rollback an update

kubectl rollout undo deployments/kubernetes-bootcamp
executing result as same as git revert