本案例要求学习使用kubectl基本命令来管理kubernetes，具体要求如下：
Kubectl是用于控制Kubernetes集群的命令行工具。
Kubectl的语法格式如下:
kubectl [command] [TYPE] [NAME] [flags]
command: 子命令，如 create，get，describe，delete
type: 资源类型，可以表示为单数，复数或缩写形式
name: 资源的名称，如果省略，则显示所有资源信息
flags: 指定可选标志，或附加的参数
实现此案例需要按照如下步骤进行。
步骤一：kubectl命令练习（在master主机操作）
1）run创建容器资源。
语法格式：kubectl run 资源名称 -i -t --image=私有仓库镜像名称:标签
- [root@master ~]# kubectl run haha -i -t --image=192.168.1.100:5000/myos:v1804
- 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.
- If you don't see a command prompt, try pressing enter.
- [root@haha-8bbd48d7b-wcnkd /]# #注意：这里已经进入了容器
- [root@haha-8bbd48d7b-wcnkd /]# ifconfig
- eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
- inet 10.244.7.2 netmask 255.255.255.0 broadcast 0.0.0.0
2)get查询资源
语法格式：
kubectl get node 查询节点状态
kubectl get deployment 查询资源名称
kubectl get pod 查询pod容器资源
kubectl get pod -o wide 查询主机信息
kubectl get pod -o yaml 显示资源文件Yaml格式
- [root@master ~]# kubectl get nodes
- NAME STATUS ROLES AGE VERSION
- master Ready master 12h v1.17.6
- node-0001 Ready <none> 16h v1.17.6
- node-0002 Ready <none> 16h v1.17.6
- node-0003 Ready <none> 16h v1.17.6
- [root@master ~]# kubectl get deployment.apps
- NAME READY UP-TO-DATE AVAILABLE AGE
- haha 1/1 1 1 10m
- [root@master ~]# kubectl get pod
- NAME READY STATUS RESTARTS AGE
- haha-xxxx 1/1 Running 1 14m
- [root@master ~]# kubectl get pod -o wide
- NAME READY STATUS RESTARTS AGE IP NODE ... ...
- haha-xxxx 1/1 Running 1 14m 10.244.7.4 node-0003 ... ...
3）exec进入一个正在运行的容器中
语法格式：
kubectl exec -it 容器id 执行的命令
- [root@kube-master ~]# kubectl get pod
- NAME READY STATUS RESTARTS AGE
- haha-8bbd48d7b-wcnkd 1/1 Running 0 31m
- #查看一个容器资源的名称
- [root@kube-master ~]# kubectl exec -it haha-8bbd48d7b-wcnkd /bin/bash
- # 进入该容器中
- [root@haha-8bbd48d7b-wcnkd /]#
4）查看资源的详细信息（主要用于排错）
语法格式：
kubectl describe 资源类型 资源名称
- [root@kube-master ~]# kubectl describe deployment haha
- # 查看deployment资源的详细信息
- Name: haha
- Namespace: default
- CreationTimestamp: Wed, 04 Mar 2020 15:50:24 +0800
- ... ...
- [root@kube-master ~]# kubectl describe pod haha-8bbd48d7b-wcnkd
- # 查看容器的详细信息
- Name: haha-8bbd48d7b-wcnkd
- Namespace: default
- Node: kube-node1/192.168.1.11
- Start Time: Wed, 04 Mar 2020 15:50:24 +0800
- Labels: pod-template-hash=466804836
- ... ...
5）查看 console 终端的输出信息
- [root@kube-master ~]# kubectl attach haha-8bbd48d7b-wcnkd -c haha -i -t
- If you don't see a command prompt, try pressing enter.
- # 先通过attach进入一个容器
- [root@haha-8bbd48d7b-wcnkd /]# echo hello world #在容器中echo输出信息
- hello world
- [root@haha-8bbd48d7b-wcnkd /]# Ctrl-p + Ctrl-q #按快捷键退出
- [root@kube-master ~]#
- [root@kube-master ~]# kubectl logs haha-8bbd48d7b-wcnkd
- [root@haha-8bbd48d7b-wcnkd /]# echo hello world
- hello world
6）delete删除资源
语法格式：
kubectl delete 资源类型 资源名称
- [root@kube-master ~]# kubectl delete pod haha-xxxxxxxx
- pod "haha-8bbd48d7b-wcnkd" deleted
- # 删除pod，注意：这里的pod名称不能照抄！！！！
- [root@kube-master ~]# kubectl get pod -o wide # 容器被删除后会自动重建
- NAME READY STATUS RESTARTS AGE IP NODE
- haha-xxxxxxxx 1/1 Running 0 3s 10.254.9.2 kube-node2
- haha-xxxxxxxx 1/1 Terminating 2 1h 10.254.39.2 kube-node1
- [root@kube-master ~]# kubectl get deployment #查看deployment资源
- NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
- haha 1 1 1 1 1h
- [root@kube-master ~]# kubectl delete deployment haha
- deployment.extensions "haha" deleted
- # 删除deployment资源，容器彻底消失
本案例要求熟悉资源文件的语法，具体要求如下：
实现此案例需要按照如下步骤进行。
步骤一：查看现有资源的资源对象文件（在master主机操作）
语法格式：
kubectl get 资源对象 资源名称 -o 格式（json|yaml）
- [root@kube-master ~]# kubectl get deployment apache -o yaml
- apiVersion: extensions/v1beta1
- kind: Deployment
- metadata:
- annotations:
- ... ...
- # 导出deployment资源的资源对象文件，depoyment资源的名称为apache，导出yaml格式
步骤二：编写资源对象文件（在master主机操作）
注意：所有资源文件都在云盘第四阶段kubernetes/v1.17.6/config/目录有案例！！！
1）Pod资源文件
- [root@master ~]# vim mypod.yaml
- ---
- kind: Pod
- apiVersion: v1
- metadata:
- name: mypod
- spec:
- containers:
- - name: mylinux
- image: 192.168.1.100:5000/myos:v1804
- stdin: true
- tty: true
- [root@master ~]# kubectl apply -f mypod.yaml
- pod/mypod created
- [root@master ~]# kubectl get pod
- NAME READY STATUS RESTARTS AGE
- mypod 1/1 Running 0 13s
- [root@master ~]# kubectl delete -f mypod.yaml
- pod "mypod" deleted
- [root@master ~]#
2）Deployment资源文件
- [root@master ~]# vim myapache.yaml
- ---
- kind: Deployment
- apiVersion: apps/v1
- metadata:
- name: myapache
- spec:
- selector:
- matchLabels:
- myapp: httpd
- replicas: 1
- template:
- metadata:
- labels:
- myapp: httpd
- spec:
- containers:
- - name: webcluster
- image: 192.168.1.100:5000/myos:httpd
- stdin: false
- tty: false
- ports:
- - protocol: TCP
- containerPort: 80
- restartPolicy: Always
- [root@master ~]# kubectl apply -f myapache.yaml
- deployment.apps/myapache created
- [root@master ~]# kubectl get deployments.apps
- NAME READY UP-TO-DATE AVAILABLE AGE
- myapache 1/1 1 1 19s
- [root@master ~]# kubectl get pod
- NAME READY STATUS RESTARTS AGE
- myapache-69b494dc5c-bff95 1/1 Running 0 28s
- [root@master ~]#
3)备注
为了建立控制器和 pod 间的关联，kubernetes 先给每个 pod 打上一个标签（Label），然后再给相应的位置定义标签选择器（Label Selector），引用这些标签，资源文件的效果如下：
- ... ...
- selector: #声明标签选择器
- app: nginx #为服务的后端选择标签
- ... ...
- metadata:
- labels: #声明标签
- app: nginx #定义标签名字(上下标签必须一致)
- ... ...
4）如何使用资源文件
使用资源文件管理对象，语法格式：kubectl (apply|create|delete) -f 资源文件
本案例主要练习集群扩容更新与回滚，分别实现以下目标：
实现此案例需要按照如下步骤进行。
步骤一：创建一个单节点的Web容器（在master主机操作操作）
资源文件在云盘的第四阶段kubernetes/v1.17.6/config/目录有案例。
各位同学需要提前下载素材文件并传到master主机。
- [root@master ~]# kubectl get deployments.apps
- NAME READY UP-TO-DATE AVAILABLE AGE
- myapache 1/1 1 1 113s
- [root@master ~]# kubectl scale deployment myapache --replicas=3
- deployment.apps/myapache scaled
- [root@master ~]# kubectl get deployments.apps
- NAME READY UP-TO-DATE AVAILABLE AGE
- myapache 3/3 3 3 2m12s
- [root@master ~]#
步骤二：集群扩容（在master主机操作操作）
我们可以使用命令行调整容器副本数量，也可以通过修改资源文件、更新资源的方式调整容器副本数量。
- [root@master ~]# kubectl scale deployment.apps httpd-example --replicas=3
步骤三：集群更新与回滚
各位同学需要提前下载素材文件并传到master主机。
- [root@master config]# kubectl rollout history deployment myapache
- deployment.apps/myapache
- REVISION CHANGE-CAUSE
- 1 <none>
- [root@master ~]# curl http://10.244.3.5
- this is apache
- [root@master ~]# kubectl edit deployments.apps myapache
- deployment.apps/myapache edited
- [root@master ~]# curl http://10.244.2.6
- this is nginx
- [root@master ~]# kubectl rollout history deployment myapache
- deployment.apps/myapache
- REVISION CHANGE-CAUSE
- 1 <none>
- 2 <none>
- [root@master ~]# kubectl rollout undo deployment myapache --to-revision=1
- deployment.apps/myapache rolled back
- [root@master ~]# curl http://10.244.3.6
- this is apache
- [root@master ~]#
步骤三：节点标签选择器
- [root@master ~]# vim myapache.yaml
- ---
- kind: Deployment
- apiVersion: apps/v1
- metadata:
- name: myapache
- spec:
- selector:
- matchLabels:
- myapp: httpd
- replicas: 1
- template:
- metadata:
- labels:
- myapp: httpd
- spec:
- nodeName: node-0001 # 新增一行
- containers:
- - name: webcluster
- image: 192.168.1.100:5000/myos:httpd
- stdin: false
- tty: false
- ports:
- - protocol: TCP
- containerPort: 80
- restartPolicy: Always
- [root@master ~]# kubectl delete -f myapache.yaml
- deployment.apps "myapache" deleted
- [root@master ~]# kubectl apply -f myapache.yaml
- deployment.apps/myapache created
- [root@master ~]# kubectl get pods -o wide
- NAME READY STATUS RESTARTS AGE IP NODE
- myapache-xxx 1/1 Running 0 3m49s 10.244.3.9 node-0001
- [root@master ~]# kubectl delete -f myapache.yaml
- deployment.apps "myapache" deleted
- [root@master ~]# kubectl get nodes --show-labels
- NAME STATUS ROLES AGE VERSION LABELS
- master Ready master 10h v1.17.6 kubernetes.io/hostname=master ... ...
- node-0001 Ready <none> 10h v1.17.6 kubernetes.io/hostname=node-0001 ... ...
- node-0002 Ready <none> 10h v1.17.6 kubernetes.io/hostname=node-0002 ... ...
- node-0003 Ready <none> 10h v1.17.6 kubernetes.io/hostname=node-0003 ... ...
- [root@master ~]# kubectl label nodes node-0002 node-0003 disktype=ssd
- node/node-0002 labeled
- node/node-0003 labeled
- [root@master ~]# kubectl get nodes --show-labels
- NAME STATUS ROLES AGE VERSION LABELS
- master Ready master 10h v1.17.6 kubernetes.io/hostname=master ... ...
- node-0001 Ready <none> 10h v1.17.6 kubernetes.io/hostname=node-0001 ... ...
- node-0002 Ready <none> 10h v1.17.6 disktype=ssd ... ...
- node-0003 Ready <none> 10h v1.17.6 disktype=ssd ... ...
- [root@master ~]# vim myapache.yaml
- ---
- kind: Deployment
- apiVersion: apps/v1
- metadata:
- name: myapache
- spec:
- selector:
- matchLabels:
- myapp: httpd
- replicas: 1
- template:
- metadata:
- labels:
- myapp: httpd
- spec:
- nodeSelector: # 新添加
- disktype: ssd # 新添加
- containers:
- - name: webcluster
- image: 192.168.1.100:5000/myos:httpd
- stdin: false
- tty: false
- ports:
- - protocol: TCP
- containerPort: 80
- restartPolicy: Always
- [root@master ~]# kubectl scale deployment myapache --replicas=3
- deployment.apps/myapache scaled
- [root@master ~]# kubectl get pod -o wide
- NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
- myapache-xxx 1/1 Running 0 9s 10.244.1.7 node-0003 <none>
- myapache-xxx 1/1 Running 0 9s 10.244.2.8 node-0002 <none>
- myapache-xxx 1/1 Running 0 21s 10.244.2.7 node-0002 <none>
- [root@master ~]# kubectl delete -f myapache.yaml
- deployment.apps "myapache" deleted
- [root@master ~]# kubectl label nodes node-0002 node-0003 disktype-
- node/node-0002 labeled
- node/node-0003 labeled
- [root@master ~]# kubectl get nodes --show-labels
- NAME STATUS ROLES AGE VERSION LABELS
- master Ready master 10h v1.17.6 kubernetes.io/hostname=master ... ...
- node-0001 Ready <none> 10h v1.17.6 kubernetes.io/hostname=node-0001 ... ...
- node-0002 Ready <none> 10h v1.17.6 kubernetes.io/hostname=node-0002 ... ...
- node-0003 Ready <none> 10h v1.17.6 kubernetes.io/hostname=node-0003 ... ...
- [root@master ~]#