kubernetes常用命令：缩容扩容回滚

查看版本

kubectl version

查看节点

kubectl get nodes

部署app

说明： 提供deployment名称和app镜像地址（docker镜像地址）

kubectl run kubernetes-bootcamp --image=gcr.io/google-samples/kubernetes-bootcamp:v1 --port=8080

再如：

run test --image=preparedman/mytomcat:tagname --port=8088

查看app

kubectl proxy

测试：curl http://localhost:8001/version

{
  "major": "1",
  "minor": "13",
  "gitVersion": "v1.13.3",
  "gitCommit": "721bfa751924da8d1680787490c54b9179b1fed0",
  "gitTreeState": "clean",
  "buildDate": "2019-02-01T20:00:57Z",
  "goVersion": "go1.11.5",
  "compiler": "gc",
  "platform": "linux/amd64"
}

获取pod名字

export POD_NAME=$(kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"
"}}{{end}}')

测试：echo Name of the Pod: $POD_NAME

使用kubectl进行故障排除

主要使用如下命令

kubectl get - list resources 列出资源
kubectl describe - show detailed information about a resource 显示资源详情
kubectl logs - print the logs from a container in a pod 打印`pod` 中container的日志
kubectl exec - execute a command on a container in a pod 在`pod`中的container上执行命令

获取应用配置

查看应用是否在运行

kubectl get pods

查看pod 中有哪些container

kubectl describe pods

结果如下：

Name:               kubernetes-bootcamp-6bf84cb898-jk4jc
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               minikube/172.17.0.72
Start Time:         Wed, 24 Apr 2019 13:21:58 +0000
Labels:             pod-template-hash=6bf84cb898
                    run=kubernetes-bootcamp
Annotations:        <none>
Status:             Running
IP:                 172.18.0.4
Controlled By:      ReplicaSet/kubernetes-bootcamp-6bf84cb898
Containers:
  kubernetes-bootcamp:
    Container ID:   docker://55491b363d26b62e432cd4841ed4f65cc5b98e645d172c6ed88feaebcb4ec06c
    Image:          gcr.io/google-samples/kubernetes-bootcamp:v1
    Image ID:       docker-pullable://jocatalin/kubernetes-bootcamp@sha256:0d6b8ee63bb57c5f5b6156f446b3bc3b3c143d233037f3a2f00e279c8fcc64af
    Port:           8080/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Wed, 24 Apr 2019 13:22:00 +0000
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-l7v8b (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-l7v8b:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-l7v8b
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  3m6s  default-scheduler  Successfully assigned default/kubernetes-bootcamp-6bf84cb898-jk4jc to minikube
  Normal  Pulled     3m4s  kubelet, minikube  Container image "gcr.io/google-samples/kubernetes-bootcamp:v1" already present on machine
  Normal  Created    3m4s  kubelet, minikube  Created container
  Normal  Started    3m4s  kubelet, minikube  Started container

打印container日志

kubectl logs $POD_NAME

在container中直接执行命令

比如：获取pod名字是kubernetes-bootcamp-6bf84cb898-jk4jc的日期，默认使用第一个container container by default

kubectl exec kubernetes-bootcamp-6bf84cb898-jk4jc date  

再入：进入container的命令行环境

kubectl exec kubernetes-bootcamp-6bf84cb898-jk4jc bash

退出使用

exit

暴露你的应用service

列出当前集群中的service

kubectl get services

创建一个新的service并暴露给外部流量

kubectl expose deployment/kubernetes-bootcamp --type="NodePort" --port 8080

查看service详情

kubectl describe services/kubernetes-bootcamp

结果：

Name:                     kubernetes-bootcamp
Namespace:                default
Labels:                   run=kubernetes-bootcamp
Annotations:              <none>
Selector:                 run=kubernetes-bootcamp
Type:                     NodePort
IP:                       10.105.231.53
Port:                     <unset>  8080/TCP
TargetPort:               8080/TCP
NodePort:                 <unset>  32400/TCP
Endpoints:                172.18.0.4:8080
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>

创建一个环境变量NODE_PORT，它的值等于service暴露的端口

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

echo NODE_PORT=$NODE_PORT

测试：

curl $(minikube ip):$NODE_PORT

使用labels

查看label

kubectl describe deployment

你能看到这样一行：

Labels:                 run=kubernetes-bootcamp

通过label查询pod

kubectl get pods -l run=kubernetes-bootcamp

通过label查询service

kubectl get services -l run=kubernetes-bootcamp

获取pod名字，并保存到环境变量POD_NAME中

export POD_NAME=$(kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"
"}}{{end}}')

echo name of the pod: $POD_NAME

添加新的lebel

使用label命令

kubectl label pod $POD_NAME app=v1

查看：

kubectl describe pods $POD_NAME

删除service

通过label删除service

kubectl delete service -l run=kubernetes-bootcamp

确认删除：

kubectl get services

确认没有暴露给集群外部：

curl $(minikube ip):$NODE_PORT

确认集群内部还可以访问：

kubectl exec -ti $POD_NAME curl localhost:8080

扩容

设置deployments的replica数量为4

kubectl scale deployments/kubernetes-bootcamp --replicas=4

查看结果：

可以看到修改replica设置生效

NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
kubernetes-bootcamp   4/4     4            4           3m17s

pod数量已经改变，查看详情

kubectl get pods -o wide

结果：

NAME                                   READY   STATUS    RESTARTS   AGE     IP           NODE       NOMINATED NODE   READINESS GATES
kubernetes-bootcamp-6bf84cb898-7tbrg   1/1     Running   0          2m50s   172.18.0.5   minikube   <none>           <none>
kubernetes-bootcamp-6bf84cb898-fx68f   1/1     Running   0          3m52s   172.18.0.4   minikube   <none>           <none>
kubernetes-bootcamp-6bf84cb898-prgsc   1/1     Running   0          2m50s   172.18.0.6   minikube   <none>           <none>
kubernetes-bootcamp-6bf84cb898-qv4gc   1/1     Running   0          2m50s   172.18.0.7   minikube   <none>           <none>

查看4个pod

kubectl describe deployments/kubernetes-bootcamp

结果：

Replicas:               4 desired | 4 updated | 4 total | 4 available | 0 unavailable

查看service是否是负载均衡的

查看具体IP

kubectl describe services/kubernetes-bootcamp

结果：

Endpoints:                172.18.0.2:8080,172.18.0.4:8080,172.18.0.6:8080 + 1 more...

创建环境变量NODE_PORT

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

echo NODE_PORT=$NODE_PORT

调用请求

可以看到，每次请求的都是不同的pod

curl $(minikube ip):$NODE_PORT

结果：

Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6bf84cb898-2l975 | v=1
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6bf84cb898-zbmj4 | v=1
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6bf84cb898-qg5xh | v=1
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6bf84cb898-zbmj4 | v=1
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6bf84cb898-bn98t | v=1
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6bf84cb898-zbmj4 | v=1
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6bf84cb898-zbmj4 | v=1
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6bf84cb898-zbmj4 | v=1

缩容

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

## 更新到版本2

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

验证更新

查看暴露出来的ip和端口

kubectl describe services/kubernetes-bootcamp

结果：

Name:                     kubernetes-bootcamp
Namespace:                default
Labels:                   run=kubernetes-bootcamp
Annotations:              <none>
Selector:                 run=kubernetes-bootcamp
Type:                     NodePort
IP:                       10.98.28.235
Port:                     <unset>  8080/TCP
TargetPort:               8080/TCP
NodePort:                 <unset>  31419/TCP
Endpoints:                172.18.0.10:8080,172.18.0.11:8080,172.18.0.8:8080 + 1 more...
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>

创建环境变量

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

echo NODE_PORT=$NODE_PORT

访问：

curl $(minikube ip):$NODE_PORT

结果：

访问版本2，且每次访问不同的地址

Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-5bf4d5689b-tcxpf | v=2
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-5bf4d5689b-tcxpf | v=2
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-5bf4d5689b-86c8g | v=2
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-5bf4d5689b-fx9tf | v=2
$ curl $(minikube ip):$NODE_PORT
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-5bf4d5689b-tcxpf | v=2

确认更新

kubectl rollout status deployments/kubernetes-bootcamp

回滚

更新到版本10

kubectl set image deployments/kubernetes-bootcamp kubernetes-bootcamp=gcr.io/google-samples/kubernetes-bootcamp:v10

查看发现报错，因为版本库中没有版本10

kubectl get deployments
kubectl get pods
kubectl describe pods

报错

Warning  Failed     38s (x3 over 77s)  kubelet, minikube  Failed to pull image "gcr.io/google-samples/kubernetes-bootcamp:v10": rpc error: code = Unknown desc = Error response from daemon: manifest for gcr.io/google-samples/kubernetes-bootcamp:v10 not found

执行会滚

kubectl rollout undo deployments/kubernetes-bootcamp