APIserver符合RESTful风格，支持GET/PUT/DELETE/POST等各种操作。所以也支持kubectl通过一系列命令对各处资源进行管理控制。
常用的资源
1)、workLoad(工作负载型资源，运行APP，对外提供服务): Pod/ReplicaSet/Deployment/ StatefulSet/ DaemonSet/ Job/ Cronjob /
2)、service discovery and Load Balance(服务发现及均衡型资源)：Service/ Ingress
3)、configuration and storage(配置与存储类型资源) ：Volume,CSI(容器存储接口，扩展第三方的存储)
ConfigMap，Secret(特殊的配置类型资源)
Downward API(配置类型资源)
4)、集群级资源(配置在名称空间级别)： namespace, node, role, clusterRole, roleBinding, clusterRoleBinding
5)、元数据类型资源：HPA、PodTemplate、limitRange（读取权限)
一、配置清单(configuration mainfest)
kubectl 通常通过ymal格式的配置清单对资源进行管理控制。APIserver仅处理Json格式定义的资源定义。ymal格式的配置清单由APIserver自动将其转为json格式，而后再提交处理。
[root@docker79 ~]# kubectl get deployment
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deploy 2 2 2 2 1d
[root@docker79 ~]# kubectl get deployment nginx-deploy -o yaml (查看nginx-deploy的配置清单)
配置清单主格式如下
apiVersion: group/version (如果group省略表示core组)
kind: Pod (资源类型)
metadata: 元数据
spec: 期望状态 disired state
status: 当前状态， current state ，本字段由kubernetes 集群维护;
[root@docker79 ~]# kubectl api-versions (查看默认支持的group与version)
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
apps/v1beta1
apps/v1beta2
authentication.k8s.io/v1
authentication.k8s.io/v1beta1
authorization.k8s.io/v1
authorization.k8s.io/v1beta1
autoscaling/v1
autoscaling/v2beta1
batch/v1
batch/v1beta1
certificates.k8s.io/v1beta1
events.k8s.io/v1beta1
extensions/v1beta1
networking.k8s.io/v1
policy/v1beta1
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
scheduling.k8s.io/v1beta1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1[root@docker79 ~]#
kubectl explain
kubectl explain Resource_Kind[.Subitem...] 查看相关resource 在定义配置清单时的帮助信息。在帮助信息中常见格式如下：
apiVersion
metadata
资源清单 例1：
[root@docker79 ~]# mkdir manifests
[root@docker79 ~]# cd manifests/
[root@docker79 manifests]# vim pod-demo.yaml
[root@docker79 manifests]# cat pod-demo.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-demo
namespace: default
labels:
app: nginx
tier: frontend
spec:
containers:
- name: nginx
image: nginx:1-alpine
- name: busybox
image: busybox:latest
command:
- "/bin/sh"
- "-c"
- "sleep 3600"[root@docker79 manifests]# kubectl create -f pod-demo.yaml
pod/pod-demo created
[root@docker79 manifests]# kubectl get pods
NAME READY STATUS RESTARTS AGE
pod-demo 2/2 Running 0 8s
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
pod-demo 2/2 Running 0 17s 10.244.1.9 docker78
[root@docker79 manifests]#
[root@docker79 manifests]# kubectl logs pod-demo busybox
[root@docker79 manifests]# kubectl logs pod-demo nginx
[root@docker79 manifests]# kubectl exec -it pod-demo -c busybox -- /bin/sh
/ # netstat -tnlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN -
/ # exit
[root@docker79 manifests]# kubectl delete -f pod-demo.yaml
pod "pod-demo" deleted
[root@docker79 manifests]#
再次修改资源清单，例2：
[root@docker79 manifests]# vim pod-demo.yaml
[root@docker79 manifests]# cat pod-demo.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-demo
namespace: default
labels:
app: nginx
tier: frontend
spec:
containers:
- name: nginx
image: nginx:1-alpine
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
name: http
- name: https
containerPort: 443[root@docker79 manifests]# kubectl apply -f pod-demo.yaml
pod/pod-demo created
[root@docker79 manifests]# kubectl get pods
NAME READY STATUS RESTARTS AGE
pod-demo 1/1 Running 0 6s
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
pod-demo 1/1 Running 0 14s 10.244.1.10 docker78
[root@docker79 manifests]#
说明：imagePullPolicy:
ports 选项可参考：kubectl explain pod.spec.containers.ports
二、Labels、Selector及 Annotation
Lables 是 key=value 格式的键值对儿。key最大长度 63字符，只能以字母或数字开头，由字母、数字、-、_、. 组成。value 最大长度 63字符，可以为空。标签支持前缀，但不能超出253字符(一般都是name或FQDN)
[root@docker79 manifests]# kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
pod-demo 1/1 Running 0 14m app=nginx,tier=frontend
[root@docker79 manifests]# kubectl get pods -L app
NAME READY STATUS RESTARTS AGE APP
pod-demo 1/1 Running 0 15m nginx
[root@docker79 manifests]# kubectl get pods -l app --show-labels
NAME READY STATUS RESTARTS AGE LABELS
pod-demo 1/1 Running 0 15m app=nginx,tier=frontend
[root@docker79 manifests]# kubectl label pods pod-demo release=canary 手工打标签
pod/pod-demo labeled
[root@docker79 manifests]# kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
pod-demo 1/1 Running 0 24m app=nginx,release=canary,tier=frontend
[root@docker79 manifests]# kubectl label pods pod-demo release=canary2 --overwrite
pod/pod-demo labeled
[root@docker79 manifests]# kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
pod-demo 1/1 Running 0 25m app=nginx,release=canary2,tier=frontend
[root@docker79 manifests]#
Selector标签选择器
支持两类：1、等值关系的标签选择器 ； 2、集合关系的标签选择器。
等值关系： = , == , !=
集合关系： in , notin
[root@docker79 manifests]# kubectl get pods -l "release in (canary,beta,alpha)"
NAME READY STATUS RESTARTS AGE
pod-demo 1/1 Running 0 28m
[root@docker79 manifests]#
标签选择器关联其它资源（如pod控制器和service) 。使用以下两个字段进行关联：
matchLabels: 直接给定键值
matchExpressions: 基于给定的表达式来定义使用标签选择器 ,定义格式如 { key: "KEY", operator: "OPERATER", value: [ VAL1, VAL2, …]}
操作符： In , NotIn (values字段的值必须为非空列表） Exists , NotExists（values字段的值必须为空列表)
节点标签选择器
nodeSelector
例：
[root@docker79 manifests]# kubectl get nodes --show-labels
NAME STATUS ROLES AGE VERSION LABELS
docker77 Ready 2d v1.11.2 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=docker77
docker78 Ready 2d v1.11.2 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=docker78
docker79 Ready master 2d v1.11.2 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=docker79,node-role.kubernetes.io/master=
[root@docker79 manifests]#
[root@docker79 manifests]# kubectl label node docker77 diskType=ssd
node/docker77 labeled
[root@docker79 manifests]# kubectl get nodes --show-labels
NAME STATUS ROLES AGE VERSION LABELS
docker77 Ready 2d v1.11.2 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,diskType=ssd,kubernetes.io/hostname=docker77
docker78 Ready 2d v1.11.2 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=docker78
docker79 Ready master 2d v1.11.2 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=docker79,node-role.kubernetes.io/master=
[root@docker79 manifests]#
[root@docker79 manifests]# kubectl delete -f pod-demo.yaml
pod "pod-demo" deleted
[root@docker79 manifests]# vim pod-demo.yaml
[root@docker79 manifests]# cat pod-demo.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-demo
namespace: default
labels:
app: nginx
tier: frontend
spec:
containers:
- name: nginx
image: nginx:1-alpine
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
name: http
- name: https
containerPort: 443
nodeSelector:
diskType: ssd
[root@docker79 manifests]#
[root@docker79 manifests]# kubectl apply -f pod-demo.yaml
pod/pod-demo created
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
pod-demo 0/1 ContainerCreating 0 17s docker77
[root@docker79 manifests]# annotations (资源注解)
与label不同之处在于： 它不能用于挑选资源对象，仅用于为对象提供“元数据”。
例：
[root@docker79 manifests]# kubectl delete -f pod-demo.yaml
pod "pod-demo" deleted
[root@docker79 manifests]# vim pod-demo.yaml
[root@docker79 manifests]# cat pod-demo.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-demo
namespace: default
labels:
app: nginx
tier: frontend
annotations:
inspiry.cn/author: "cluster admin"
spec:
containers:
- name: nginx
image: nginx:1-alpine
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
name: http
- name: https
containerPort: 443
nodeSelector:
diskType: ssd
[root@docker79 manifests]# kubectl apply -f pod-demo.yaml
pod/pod-demo created
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
pod-demo 1/1 Running 0 13s 10.244.2.9 docker77
[root@docker79 manifests]# kubectl describe pod pod-demo
Name: pod-demo
Namespace: default
Priority: 0
PriorityClassName:
Node: docker77/192.168.20.77
Start Time: Wed, 26 Sep 2018 16:25:44 +0800
Labels: app=nginx
tier=frontend
Annotations: inspiry.cn/author=cluster admin
...... 三、pod生命周期
状态： Pending ， Running ，Failed， Successded ， Unknown
Pod生命周期中的重要行为：
1) 初始化container
2) container探测：liveness probe（存活探测) 和 readiness probe (就绪探测)
以上两种探测使用的探针类型有：ExeAction、TCPSocketAction、HTTPGetAction
探针探测时的常用选项如下：
failureThreshold 探测多少次宣告失败，默认3次
periodSeconds 每次间隔时长，默认10s
timeoutSeconds 每次的超时时长，默认1s
initialDelaySeconds 初始延时的时长，默认立即探测
探测结果的重启策略restartPolicy 有以下三种值：
Always: 一旦故障，立即重启
Never: 不重启
OnFailure: 只有出现 failure状态时才重启
3) 启动后勾子和中止前勾子 lifecycle
kubectl explain pods.spec.containers.lifecycle.postStart
kubectl explain pods.spec.containers.lifecycle.preStop
例1-liveness：
[root@docker79 manifests]# vim liveness-exec.yaml
[root@docker79 manifests]# cat liveness-exec.yaml
apiVersion: v1
kind: Pod
metadata:
name: liveness-exec-pod
namespace: default
spec:
containers:
- name: liveness-exec-container
image: busybox:latest
imagePullPolicy: IfNotPresent
command: ["/bin/sh", "-c", "touch /tmp/healthy; sleep 30; rm -f /tmp/healthy; sleep 3600" ]
livenessProbe:
exec:
command: ["test", "-e" , "/tmp/health"]
initialDelaySeconds: 1
periodSeconds: 3
restartPolicy: Never
[root@docker79 manifests]# kubectl apply -f liveness-exec.yaml
pod/liveness-exec-pod created
[root@docker79 manifests]# kubectl get pods
NAME READY STATUS RESTARTS AGE
liveness-exec-pod 1/1 Running 0 6s
pod-demo 1/1 Running 0 18m
[root@docker79 manifests]# kubectl get pods
NAME READY STATUS RESTARTS AGE
liveness-exec-pod 0/1 Error 0 51s
pod-demo 1/1 Running 0 19m
[root@docker79 manifests]#说明：container启动之后在30s之内 成功探测/tmp/health 文件存在，所以container status处于running状态；但30s之后/tmp/health文件被rm，导致探测/tmp/health文件不存在，所以container status处于Eroor 。
例2-liveness：
[root@docker79 manifests]# vim liveness-httpsocket.yaml
[root@docker79 manifests]# cat liveness-httpsocket.yaml
apiVersion: v1
kind: Pod
metadata:
name: liveness-httpget-pod
namespace: default
spec:
containers:
- name: liveness-httpget-container
image: nginx:1-alpine
imagePullPolicy: IfNotPresent
ports:
- name: http
containerPort: 80
livenessProbe:
httpGet:
port: http
path: /index.html
initialDelaySeconds: 1
periodSeconds: 3
[root@docker79 manifests]# kubectl apply -f liveness-httpsocket.yaml
pod/liveness-httpget-pod created
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
liveness-httpget-pod 1/1 Running 0 8s 10.244.1.13 docker78
pod-demo 1/1 Running 0 2h 10.244.2.9 docker77
[root@docker79 manifests]#
[root@docker79 manifests]# kubectl exec -it liveness-httpget-pod -- /bin/sh
/ # ls /usr/share/nginx/html/
50x.html index.html
/ # rm /usr/share/nginx/html/index.html -f
/ # exit
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
liveness-httpget-pod 1/1 Running 1 2m 10.244.1.13 docker78
pod-demo 1/1 Running 0 2h 10.244.2.9 docker77
[root@docker79 manifests]# 说明：当httpGetAction探针探测到无法访问 /index.html 时，立即执行restartPolicy重启策略，该策略默认值always，所以可以看到 pod 的 restarts 为1.
例3-readiness：
[root@docker79 manifests]# vim readiness-httpget.yaml
[root@docker79 manifests]# cat readiness-httpget.yaml
apiVersion: v1
kind: Pod
metadata:
name: readiness-httpget-pod
namespace: default
spec:
containers:
- name: readiness-httpget-container
image: nginx:1-alpine
imagePullPolicy: IfNotPresent
ports:
- name: http
containerPort: 80
readinessProbe:
httpGet:
port: http
path: /index.html
initialDelaySeconds: 1
periodSeconds: 3
[root@docker79 manifests]# kubectl apply -f readiness-httpget.yaml
pod/readiness-httpget-pod created
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
pod-demo 1/1 Running 0 3h 10.244.2.9 docker77
readiness-httpget-pod 1/1 Running 0 9s 10.244.1.14 docker78
[root@docker79 manifests]# kubectl exec -it readiness-httpget-pod -- /bin/sh
/ # rm -f /usr/share/nginx/html/index.html
/ #
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
pod-demo 1/1 Running 0 3h 10.244.2.9 docker77
readiness-httpget-pod 0/1 Running 0 1m 10.244.1.14 docker78
[root@docker79 manifests]# kubectl exec -it readiness-httpget-pod -- /bin/sh
/ # echo readiness > /usr/share/nginx/html/index.html
/ # [root@docker79 manifests]#
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
pod-demo 1/1 Running 0 3h 10.244.2.9 docker77
readiness-httpget-pod 1/1 Running 0 2m 10.244.1.14 docker78
[root@docker79 manifests]# 说明：就绪探测与service 调度有紧密关联，只有就绪的pod才能被调度。例3中当删除/usr/share/nginx/html/index.html之后，探针无法获取/index.html，所以pod的READY状态处于0/1状态；当再次创建/usr/share/nginx/html/index.html之后，探针有效探测到/index.html之后，pod的READY状态处于1/1状态。
例4-lifecycle：
[root@docker79 manifests]# vim lifecycle-poststart.yaml
[root@docker79 manifests]# cat lifecycle-poststart.yaml
apiVersion: v1
kind: Pod
metadata:
name: lifecycle-poststart-pod
namespace: default
spec:
containers:
- name: lifecycle-poststart-container
image: busybox:latest
imagePullPolicy: IfNotPresent
lifecycle:
postStart:
exec:
command: ["mkdir","-p","/var/www/inspiry"]
command: ["/bin/sh","-c","sleep 60; /bin/httpd -f -h /var/www/inspiry"]
[root@docker79 manifests]# kubectl apply -f lifecycle-poststart.yaml
pod/lifecycle-poststart-pod created
[root@docker79 manifests]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
lifecycle-poststart-pod 1/1 Running 0 9s 10.244.1.15 docker78
[root@docker79 manifests]# kubectl exec -it lifecycle-poststart-pod -- /bin/sh
/ # ls /var/www/
inspiry
/ # netstat -tnlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 :::80 :::* LISTEN 1/httpd
/ # exit
[root@docker79 manifests]# 说明：例4中使用lifecycle.postStart.exec 表示pod中container启动后执行的命令.