k8s快速入门
1.快速创建k8s集群
参考网站：https://kubernetes.io/docs/tutorials/kubernetes-basics
点击教程菜单 1. Create a Cluster -> Interactive Tutorial - Creating a Cluster
note：通过 Kubernetes 的命令行工具 kubectl 远程管理集群- minikube start 创建集群
- kubectl cluster-info 查看集群信息
Kubernetes master is running at https://172.17.0.15:8443
KubeDNS is running at https://172.17.0.15:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy- kubectl get nodes 查看节点信息
NAME STATUS ROLES AGE VERSION
minikube Ready master 2m53s v1.13.32.部署应用
kubectl run kubernetes-bootcamp --image=docker.io/jocatalin/kubernetes-bootcamp:v1 --port=8080
显示信息
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/kubernetes-bootcamp created这里我们通过 kubectl run 部署了一个应用，命名为 kubernetes-bootcamp
--image 指定Docker 镜像
--port 设置应用对外服务的端口
3.访问应用
默认情况下，所有 Pod只能在集群内部访问。为了能够从外部访问应用，我们需要将容器的 8080 端口映射到节点的端口。
kubectl expose deployment/kubernetes-bootcamp --type="NodePort" --port 8080
显示信息
service/kubernetes-bootcamp exposed查看services及对应的映射端口
kubectl get services
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 9m47s
kubernetes-bootcamp NodePort 10.105.140.245 <none> 8080:31048/TCP 82skubernetes 是默认的 service，暂时不用考虑。kubernetes-bootcamp 是我们应用的 service，8080 端口已经映射到 host01 的 31048 端口，端口号是随机分配的
通过curl命令进行访问
curl host01:30393
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6c5cfd894b-ccqz7 | v=14.Scale 应用
默认情况下应用只会运行一个副本，可以通过 kubectl get deployments查看副本数。
kubectl get deployments
NAME READY UP-TO-DATE AVAILABLE AGE
kubernetes-bootcamp 1/1 1 1 2m增加副本个数
kubectl scale deployments/kubernetes-bootcamp --replicas=3deployment.extensions/kubernetes-bootcamp scaled
$ kubectl get deployments
NAME READY UP-TO-DATE AVAILABLE AGE
kubernetes-bootcamp 3/3 3 3 2m34s减少副本个数
$ kubectl scale deployments/kubernetes-bootcamp --replicas=1
deployment.extensions/kubernetes-bootcamp scaled
$ kubectl get deployments
NAME READY UP-TO-DATE AVAILABLE AGE
kubernetes-bootcamp 1/1 1 1 3m51s
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
kubernetes-bootcamp-6c5cfd894b-9cn54 1/1 Running 0 41s
kubernetes-bootcamp-6c5cfd894b-ccqz7 1/1 Running 0 4m44s
kubernetes-bootcamp-6c5cfd894b-gnhgz 1/1 Running 0 41s
$ kubectl scale deployments/kubernetes-bootcamp --replicas=1
deployment.extensions/kubernetes-bootcamp scaled
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
kubernetes-bootcamp-6c5cfd894b-9cn54 1/1 Terminating 0 57s
kubernetes-bootcamp-6c5cfd894b-ccqz7 1/1 Running 0 5m
kubernetes-bootcamp-6c5cfd894b-gnhgz 1/1 Terminating 0 57s4.滚动更新
当前应用使用的 image 版本为 v1，执行如下命令将其升级到 v2：
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$ kubectl set image deployments/kubernetes-bootcamp kubernetes-bootcamp=jocatalin/kubernetes-bootcamp:v2
deployment.extensions/kubernetes-bootcamp image updated
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
kubernetes-bootcamp-5bf4d5689b-4k5lb 1/1 Running 0 3s
kubernetes-bootcamp-5bf4d5689b-b9szr 1/1 Running 0 4s
kubernetes-bootcamp-5bf4d5689b-sxxs5 1/1 Running 0 4s
kubernetes-bootcamp-5bf4d5689b-zftkx 1/1 Running 0 3s
kubernetes-bootcamp-6c5cfd894b-ccqz7 1/1 Terminating 0 6m25s
kubernetes-bootcamp-6c5cfd894b-r4mtd 1/1 Terminating 0 6s
kubernetes-bootcamp-6c5cfd894b-r6txw 1/1 Terminating 0 6s
kubernetes-bootcamp-6c5cfd894b-vnbd6 1/1 Terminating 0 6s
$ curl host01:30393
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-5bf4d5689b-zftkx | v=2通过 kubectl get pods 可以观察滚动更新的过程：v1 的 Pod 被逐个删除，同时启动了新的 v2 Pod。更新完成后访问新版本应用。
如果要回退到 v1 版本也很容易，执行 kubectl rollout undo 命令：
$ kubectl rollout undo deployments/kubernetes-bootcamp
deployment.extensions/kubernetes-bootcamp rolled back
$ curl host01:30393
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-6c5cfd894b-pq7kv | v=1