k8s常用指令
常用指令
案例演示1： 通过对web应用的部署，暴露，升级，回滚，扩容来演示kubectl指令的使用
1 部署一个web应用
[root@master kubectl-cmd]# kubectl create deployment java-demo --image=tomcat
deployment.apps/java-demo created
[root@master kubectl-cmd]#
[root@master kubectl-cmd]# kubectl get pods
NAME READY STATUS RESTARTS AGE
java-demo-6bdbd5ffbf-fr8wc 1/1 Running 0 102s
[root@master kubectl-cmd]#
2 把这个应用暴露出去
[root@master kubectl-cmd]# kubectl expose deployment java-demo --port=80 --target-port=8080 --name=java-demo --type=NodePort
service/java-demo exposed
[root@master kubectl-cmd]#
[root@master kubectl-cmd]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
java-demo NodePort 10.98.211.51 <none> 80:32166/TCP 11s
[root@master kubectl-cmd]#
命令格式：
kubectl expose (-f FILENAME | TYPE NAME) [--port=port] [--protocol=TCP|UDP|SCTP] [--target-port=number-or-name][--name=name][--external-ip=external-ip-of-service] [--type=type] [options]
命令解析：
暴露的资源类型是deployment
deployment的名字是depname-java
--port=80 对外暴露集群内容的端口是80
--target-port=8080 镜像中应用程序提供的端口是8080
--name=java-demo 暴露的这个service的名字是java-demo
--type=NodePort 暴露出去的端口类型是NodePort
3 对这个应用进行升级
通过替换容器的方式，把名称为java-demo的deployment中containers中镜像的名字由tomcat替换成nginx
[root@master kubectl-cmd]# kubectl set image deployment java-demo tomcat=nginx
deployment.apps/java-demo image updated
[root@master kubectl-cmd]#
查看containters中容器名称的方法：
[root@master kubectl-cmd]# kubectl get deployment java-demo -o yaml
template:
metadata:
creationTimestamp: null
labels:
app: java-demo
spec:
containers:
- image: tomcat
imagePullPolicy: Always
name: tomcat
注意：
升级之前web是tomcat，默认端口是8080，升级之后web是nginx 默认端口是80,所以需要手动修改这个要修改service.的targetPort,把它修改为80
[root@master kubectl-cmd]# kubectl edit svc java-demo
spec:
clusterIP: 10.98.211.51
externalTrafficPolicy: Cluster
ports:
- nodePort: 32166
port: 80
protocol: TCP
targetPort: 80
4 应用回滚
[root@master kubectl-cmd]# kubectl rollout undo deployment java-demo #回滚到上一个版本
deployment.apps/java-demo rolled back
[root@master kubectl-cmd]#
[root@master kubectl-cmd]# kubectl get pods
NAME READY STATUS RESTARTS AGE
java-demo-6bdbd5ffbf-75l8f 1/1 Running 0 19s
java-demo-759fc8c66c-qqwxz 1/1 Terminating 0 28m
[root@master kubectl-cmd]#
[root@master kubectl-cmd]# kubectl get pods
NAME READY STATUS RESTARTS AGE
java-demo-6bdbd5ffbf-75l8f 1/1 Running 0 86s
[root@master kubectl-cmd]#
注意：
要把service中端口修改为8080
5 扩容/缩容
[root@master kubectl-cmd]# kubectl scale deployment java-demo --replicas=3
deployment.apps/java-demo scaled
[root@master kubectl-cmd]# kubectl get pods
NAME READY STATUS RESTARTS AGE
java-demo-6bdbd5ffbf-75l8f 1/1 Running 0 5m40s
java-demo-6bdbd5ffbf-bjzjd 1/1 Running 0 45s
java-demo-6bdbd5ffbf-xdhgp 1/1 Running 0 45s
[root@master kubectl-cmd]#
案例演示2：通过对yaml文件的介绍来演示kubectl指令的使用
YAML的介绍
它是一种简介的非标记语言
YAML文件格式
缩进表示层级关系
不支持制表符“tab”缩进，使用空格缩进
通常开头缩进 2 个空格
字符后缩进 1 个空格，如冒号、逗号等
“---” 表示YAML格式，一个文件的开始
“#”注释
1 从官网拷贝ymal案例
https://kubernetes.io/docs/tutorials/kubernetes-basics/官网搜索deployment，找到一个案例，用vim编辑器进行部分修改
apiVersion:
查看k8s所支持的aipVersion
[root@master ~]# kubectl api-versions
admissionregistration.k8s.io/v1
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
authentication.k8s.io/v1
authentication.k8s.io/v1beta1
authorization.k8s.io/v1
authorization.k8s.io/v1beta1
autoscaling/v1
autoscaling/v2beta1
autoscaling/v2beta2
batch/v1
batch/v1beta1
certificates.k8s.io/v1beta1
coordination.k8s.io/v1
coordination.k8s.io/v1beta1
discovery.k8s.io/v1beta1
events.k8s.io/v1beta1
extensions/v1beta1
networking.k8s.io/v1
networking.k8s.io/v1beta1
node.k8s.io/v1beta1
policy/v1beta1
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
scheduling.k8s.io/v1
scheduling.k8s.io/v1beta1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1
[root@master ~]#
原数据metadata：
通常包括：资源的名称和命名空间
[root@master ~]# kubectl get ns
NAME STATUS AGE
default Active 293d
ingress-nginx Active 40d
kube-node-lease Active 293d
kube-public Active 293d
kube-system Active 293d
kubernetes-dashboard Active 293d
ops Active 7d19h
test Active 3d11h
[root@master ~]#
2 用指令生成yaml文件
生成一个deployment文件
[root@master kubectl-cmd]# kubectl create deployment web --image=nginx --dry-run=client -o yaml
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
labels:
app: web
name: web
spec:
replicas: 1
selector:
matchLabels:
app: web
strategy: {}
template:
metadata:
creationTimestamp: null
labels:
app: web
spec:
containers:
- image: nginx
name: nginx
resources: {}
status: {}
[root@master kubectl-cmd]#
生成一个service文件
[root@master kubectl-cmd]# kubectl apply -f deploy1.yaml
deployment.apps/web created
[root@master kubectl-cmd]# kubectl expose deployment web --port=80 --type=NodePort --target-port=80 --name=web --dry-run=client -o yaml
apiVersion: v1
kind: Service
metadata:
creationTimestamp: null
labels:
app: web
name: web
spec:
ports:
- port: 80
protocol: TCP
targetPort: 80
selector:
app: web
type: NodePort
status:
loadBalancer: {}
[root@master kubectl-cmd]#
3 有get 指令导出现有资源的yaml文件
[root@master kubectl-cmd]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
java-demo 3/3 3 3 22h
nfs-client-provisioner 1/1 1 1 7d20h
web 1/1 1 1 6m6s
[root@master kubectl-cmd]#
[root@master kubectl-cmd]#
[root@master kubectl-cmd]# kubectl get deployment java-demo -o yaml --export
查看当前k8s系统中资源类型的缩写
[root@master kubectl-cmd]# kubectl api-resources
查看某一资源层级下有哪些资源可以使用
kubectl explain <type>.<fieldName>[.<fieldName>]
[root@master kubectl-cmd]# kubectl explain deployment.spec.template.spec.containers
[root@master kubectl-cmd]# kubectl explain pods.spec.containers
指令补全功能
[root@master kubectl-cmd]# yum search bash-comp
[root@master kubectl-cmd]# yum install -y bash-completion.noarch
[root@master kubectl-cmd]# source /usr/share/bash-completion/bash_completion
[root@master kubectl-cmd]# source <(kubectl completion bash)
[root@master kubectl-cmd]#
