K8s的五种控制器类型解析
文章目录
- 前言
- K8S的五种控制器
-
- 控制器类型介绍
- Pod与控制器之间的关系
- 1. Deployment控制器
-
- 测试deployment控制器
- 编写yaml文件，并创建nginx服务pod资源
- 查看控制器
- 更新机制：
- 查看历史版本
- 2. SatefulSet 控制器
-
- 部署有状态应用
- 无状态服务的特点：
- 有状态服务的特点
- headless方式（因为Pod动态IP地址，所以常用于绑定DNS访问）
- 复制coredns.yaml到master01的root家目录
- DNS 域名解析，解析成功
- 总结
- 3 . DaemonSet 控制器
-
- 检查资源
- 4. Job 控制器
-
- 一次性执行
- 5 . CronJob 控制器
-
- 周期性任务
前言
K8S的五种控制器
控制器类型介绍
控制器：又称之为工作负载，分别包含以下类型控制器
1：Deployment
2：StatefulSet
3：DaemonSet
4：Job
5：CronJob
Pod与控制器之间的关系
controllers：在集群上管理和运行容器的对象通过label-selector相关联
Pod通过控制器实现应用的运维，如伸缩，升级等
控制器又被称为工作负载，pod通过控制器实现应用的运维，比如伸缩、升级等
1. Deployment控制器
适合部署无状态的应用服务，用来管理pod和replicaset，具有上线部署、副本设定、滚动更新、回滚等功能，还可提供声明式更新，例如只更新一个新的Image
测试deployment控制器
编写yaml文件，并创建nginx服务pod资源
//Replicaset 是控制版本，副本数，回滚就是通过此来实现
[root@master demo]# vim nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3 '//指定副本数为3'
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx1
image: nginx:1.15.4
ports:
- containerPort: 80
创建pod资源
[root@master demo]# kubectl create -f nginx-deployment.yaml
deployment.apps/nginx-deployment created
查看资源
[root@master demo]# kubectl get pods,deploy,rs
NAME READY STATUS RESTARTS AGE
pod/nginx-deployment-78cdb5b557-8gxc2 1/1 Running 0 88s
pod/nginx-deployment-78cdb5b557-pnkmb 1/1 Running 0 88s
pod/nginx-deployment-78cdb5b557-v6tr9 1/1 Running 0 88s
pod/pod-example 1/1 Running 0 29m
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
deployment.extensions/nginx-deployment 3 3 3 3 88s
NAME DESIRED CURRENT READY AGE
replicaset.extensions/nginx-deployment-78cdb5b557 3 3 3 88s
查看控制器
查看控制器参数：可以使用describe或者edit两种方式
[root@localhost demo]# kubectl edit deployment/nginx-deployment
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "1"
creationTimestamp: 2020-10-14T11:48:34Z
generation: 1
labels:
app: nginx
name: nginx-deployment
namespace: default
resourceVersion: "89774"
selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/nginx-deployment
uid: 304e5d7b-0e13-11eb-9770-000c2994a1fc
spec:
progressDeadlineSeconds: 600
replicas: 3
revisionHistoryLimit: 10
selector:
matchLabels:
app: nginx
strategy: //'此段解释的是滚动更新机制'
rollingUpdate:
maxSurge: 25% // //25%指的是pod数量的百分比，最多可以扩容125%'
maxUnavailable: 25% //'//25%指的是pod数量的百分比，最多可以缩容75%'
"/tmp/kubectl-edit-0xo04.yaml" 70L, 1962C
更新机制：
会先增加25% ，在删除25% ，保持资源数量在 replicas 值范围 在设定值
查看历史版本
[root@master demo]# kubectl rollout history deployment/nginx-deployment
deployment.extensions/nginx-deployment
REVISION CHANGE-CAUSE
1
2. SatefulSet 控制器
部署有状态应用
解决Pod独立生命周期，保持Pod启动顺序和唯一性
稳定，唯一的网络标识符，持久存储（例如：etcd配置文件，节点地址发生变化，将无法使用）
有序，优雅的部署和扩展、删除和终止（例如：mysql主从关系，先启动主，再启动从）
有序，滚动更新
应用场景：数据库
https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/
无状态服务的特点：
1）deployment 认为所有的pod都是一样的
2）不用考虑顺序的要求
3）不用考虑在哪个node节点上运行
4）可以随意扩容和缩容
有状态服务的特点
1）实例之间有差别，每个实例都有自己的独特性，元数据不同，例如etcd，zookeeper
2）实例之间不对等的关系，以及依靠外部存储的应用。
常规service和无头服务区别
service：一组Pod访问策略，提供cluster-IP群集之间通讯，还提供负载均衡和服务发现。
Headless service 无头服务，不需要cluster-IP，直接绑定具体的Pod的IP
[root@master demo]# !vim
vim nginx-service.yaml
apiVersion: v1
kind: Service
metadata:
name: nginx-service
labels:
app: nginx
spec:
type: NodePort
ports:
- port: 80
targetPort: 80
selector:
app: nginx
创建资源
[root@master demo]# kubectl create -f nginx-service.yaml
service/nginx-service created
查看资源
[root@master demo]# kubectl get pods,svc
NAME READY STATUS RESTARTS AGE
pod/nginx-deployment-78cdb5b557-8gxc2 1/1 Running 0 24m
pod/nginx-deployment-78cdb5b557-pnkmb 1/1 Running 0 24m
pod/nginx-deployment-78cdb5b557-v6tr9 1/1 Running 0 24m
pod/pod-example 1/1 Running 0 52m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 4d10h
service/nginx-service NodePort 10.0.0.65 <none> 80:49741/TCP 59s
//在node节点上操作
systemctl restart flanneld.service
systemctl restart docker
[root@node2 ~]# curl 10.0.0.65
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
headless方式（因为Pod动态IP地址，所以常用于绑定DNS访问）
[root@master demo]# vim headless.yaml
apiVersion: v1
kind: Service '//创建一个service类型的资源'
metadata:
name: nginx
labels:
app: nginx
spec:
ports:
- port: 80
name: web
clusterIP: None '//不使用clusterIP'
selector:
app: nginx
查看service 资源
[root@master demo]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 4d11h
nginx ClusterIP None <none> 80/TCP 27s //'//刚刚创建的无头服务没有clusterIP'
nginx-service NodePort 10.0.0.65 <none> 80:49741/TCP 90m
[root@master demo]#
复制coredns.yaml到master01的root家目录
官方文档地址：
https://www.kubernetes.org.cn/4694.html
下载 coredns.yaml 文件
[root@master opt]# ls
coredns.yaml demo dockersoft etcd kubernetes rh
创建DNS资源
、配置dns服务，使用yaml文件创建
[root@master test]# vim coredns.yaml
# Warning: This is a file generated from the base underscore template file: coredns.yaml.base
apiVersion: v1
kind: ServiceAccount '//系统账户，为pod中的进程和外部用户提供身份信息'
metadata:
name: coredns
namespace: kube-system '//指定名称空间'
labels:
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole '//创建访问权限的角色'
metadata:
labels:
kubernetes.io/bootstrapping: rbac-defaults
addonmanager.kubernetes.io/mode: Reconcile
name: system:coredns
rules:
- apiGroups:
- ""
resources:
- endpoints
- services
- pods
- namespaces
verbs:
- list
- watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding '//创建集群角色绑定的用户'
metadata:
annotations:
rbac.authorization.kubernetes.io/autoupdate: "true"
labels:
kubernetes.io/bootstrapping: rbac-defaults
addonmanager.kubernetes.io/mode: EnsureExists
name: system:coredns
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: system:coredns
subjects:
- kind: ServiceAccount
name: coredns
namespace: kube-system
---
apiVersion: v1
kind: ConfigMap '//通过此服务来更改服务发现的工作方式'
metadata:
name: coredns
namespace: kube-system
labels:
addonmanager.kubernetes.io/mode: EnsureExists
data:
Corefile: | '//是coreDNS的配置文件'
.:53 {
errors
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
proxy . /etc/resolv.conf
cache 30
loop
reload
loadbalance
}
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: coredns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
kubernetes.io/name: "CoreDNS"
spec:
# replicas: not specified here:
# 1. In order to make Addon Manager do not reconcile this replicas parameter.
# 2. Default is 1.
# 3. Will be tuned in real time if DNS horizontal auto-scaling is turned on.
strategy:
type: RollingUpdate
rollingUpdate:
maxUnavailable: 1
selector:
matchLabels:
k8s-app: kube-dns
template:
metadata:
labels:
k8s-app: kube-dns
annotations:
seccomp.security.alpha.kubernetes.io/pod: 'docker/default'
spec:
serviceAccountName: coredns
tolerations:
- key: node-role.kubernetes.io/master
effect: NoSchedule
- key: "CriticalAddonsOnly"
operator: "Exists"
containers:
- name: coredns
image: coredns/coredns:1.2.2
imagePullPolicy: IfNotPresent
resources:
limits:
memory: 170Mi
requests:
cpu: 100m
memory: 70Mi
args: [ "-conf", "/etc/coredns/Corefile" ]
volumeMounts:
- name: config-volume
mountPath: /etc/coredns
readOnly: true
ports:
- containerPort: 53
name: dns
protocol: UDP
- containerPort: 53
name: dns-tcp
protocol: TCP
- containerPort: 9153
name: metrics
protocol: TCP
livenessProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
securityContext:
allowPrivilegeEscalation: false
capabilities:
add:
- NET_BIND_SERVICE
drop:
- all
readOnlyRootFilesystem: true
dnsPolicy: Default
volumes:
- name: config-volume
configMap:
name: coredns
items:
- key: Corefile
path: Corefile
---
apiVersion: v1
kind: Service
metadata:
name: kube-dns
namespace: kube-system
annotations:
prometheus.io/port: "9153"
prometheus.io/scrape: "true"
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
kubernetes.io/name: "CoreDNS"
spec:
selector:
k8s-app: kube-dns
clusterIP: 10.0.0.2
ports:
- name: dns
port: 53
protocol: UDP
- name: dns-tcp
port: 53
protocol: TCP
创建资源
[root@master opt]# kubectl create -f coredns.yaml
serviceaccount/coredns created
clusterrole.rbac.authorization.k8s.io/system:coredns created
clusterrolebinding.rbac.authorization.k8s.io/system:coredns created
configmap/coredns created
deployment.extensions/coredns created
service/kube-dns created
查看资源
[root@master opt]# kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-56684f94d6-rsfqv 0/1 ContainerCreating 0 24s
kubernetes-dashboard-7dffbccd68-gzlkg 1/1 Running 1 4d10h
[root@master opt]# kubectl get pods -n kube-system -w
NAME READY STATUS RESTARTS AGE
coredns-56684f94d6-rsfqv 0/1 ContainerCreating 0 31s
kubernetes-dashboard-7dffbccd68-gzlkg 1/1 Running 1 4d10h
coredns-56684f94d6-rsfqv 1/1 Running 0 41s
‘//创建用来测试dns的pod资源’
vim pod8.yaml
apiVersion: v1
kind: Pod
metadata:
name: dns-test
spec:
containers:
- name: busybox
image: busybox:1.28.4
args:
- /bin/sh
- -c
- sleep 36000
restartPolicy: Never
创建资源
kubectl create -f pod8.yaml
[root@master demo]# kubectl get all
NAME READY STATUS RESTARTS AGE
pod/dns-test 1/1 Running 0 5m5s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 4d12h
service/nginx ClusterIP None <none> 80/TCP 2m4s
service/nginx-service NodePort 10.0.0.154 <none> 80:45247/TCP 3s
进入dns-test容器，查看DNS主机名解析
[root@master demo]# kubectl exec -it dns-test sh
/ # nslookup kubernetes
Server: 10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local
Name: kubernetes
Address 1: 10.0.0.1 kubernetes.default.svc.cluster.local
/ # nslookup nginx-service
Server: 10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local
Name: nginx-service
Address 1: 10.0.0.154 nginx-service.default.svc.cluster.local
/ #
创建YAML文件,
[root@master demo]# vim sts.yaml
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
ports:
- port: 80
name: web
clusterIP: None
selector:
app: nginx
---
apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
name: nginx-statefulset
namespace: default
spec:
serviceName: nginx
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:latest
ports:
- containerPort: 80
清理所有pods
[root@master demo]# kubectl delete -f .
创建资源
[root@master demo]# kubectl create -f sts.yaml
service/nginx created
statefulset.apps/nginx-statefulset created
[root@master demo]# kubectl get pods
NAME READY STATUS RESTARTS AGE
dns-test 1/1 Running 0 7m57s
nginx-statefulset-0 1/1 Running 0 2m1s
nginx-statefulset-1 1/1 Running 0 49s
nginx-statefulset-2 1/1 Running 0 46s
[root@master demo]# kubectl get pods,svc
NAME READY STATUS RESTARTS AGE
pod/dns-test 1/1 Running 0 9m1s
pod/nginx-statefulset-0 1/1 Running 0 3m5s
pod/nginx-statefulset-1 1/1 Running 0 113s
pod/nginx-statefulset-2 1/1 Running 0 110s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 4d12h
service/nginx ClusterIP None <none> 80/TCP 3m5s
[root@master demo]# kubectl get ep
NAME ENDPOINTS AGE
kubernetes 192.168.100.3:6443,192.168.100.8:6443 4d12h
nginx 172.17.16.4:80,172.17.18.3:80,172.17.18.4:80 5m35s
DNS 域名解析，解析成功
[root@master demo]# kubectl exec -it dns-test sh
/ # nslookup nginx-statefulset-0.nginx
Server: 10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local
Name: nginx-statefulset-0.nginx
Address 1: 172.17.18.3 nginx-statefulset-0.nginx.default.svc.cluster.local
/ # nslookup nginx-statefulset-1.nginx
Server: 10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local
Name: nginx-statefulset-1.nginx
Address 1: 172.17.16.4 nginx-statefulset-1.nginx.default.svc.cluster.local
/ # nslookup nginx-statefulset-2.nginx
Server: 10.0.0.2
Address 1: 10.0.0.2 kube-dns.kube-system.svc.cluster.local
Name: nginx-statefulset-2.nginx
Address 1: 172.17.18.4 nginx-statefulset-2.nginx.default.svc.cluster.local
/ #
节点访问 172.17.18.3
总结
StatefulSet与Deployment区别：有身份的！
身份三要素：
域名 nginx-statefulset-0.nginx
主机名 nginx-statefulset-0
存储（PVC）
3 . DaemonSet 控制器
在每一个Node上运行一个Pod
新加入的Node也同样会自动运行一个Pod
应用场景：Agent （代理）
官方文档：
https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/
示例1
[root@master demo]# vim ds.yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.15.4
ports:
- containerPort: 80
-
[root@master demo]# kubectl apply -f ds.yaml
daemonset.apps/nginx-deployment created
检查资源
因为yaml 文件并未设置副本集， 然而却自动每个节点都创造了一个deployment
可见，DaemonSet会在每个node节点都创建一个Pod
root@master demo]# kubectl get pods
NAME READY STATUS RESTARTS AGE
dns-test 1/1 Running 0 27m
nginx-deployment-7gvsx 1/1 Running 0 31s
nginx-deployment-qgzgm 1/1 Running 0 31s
4. Job 控制器
Job分为普通任务（Job）和定时任务（CronJob）
一次性执行
应用场景：离线数据处理，视频解码等业务
官方文档：
https://kubernetes.io/docs/concepts/workloads/controllers/jobs-run-to-completion/
示例：
//示例中当遇到异常时Never状态不会重启。
[root@master demo]# vim job.yaml
apiVersion: batch/v1
kind: Job
metadata:
name: pi
spec:
template:
spec:
containers:
- name: pi
image: perl
command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
restartPolicy: Never //不重启
# backoffLimit: 4 //重启次数
//在node节点下载perl镜像，因为镜像比较大所以提前下载好
[root@node1 ~]# docker pull perl
创建资源，用perl 语言去计算圆周率
[root@master demo]# kubectl apply -f job.yaml
job.batch/pi created
查看状态
因为是一次性任务，在执行完任务后，会自动结束
[root@master demo]# kubectl get pods
NAME READY STATUS RESTARTS AGE
dns-test 1/1 Running 0 36m
nginx-deployment-7gvsx 1/1 Running 0 10m
nginx-deployment-qgzgm 1/1 Running 0 10m
pi-fd25w 0/1 Completed 0 36s
查看执行的结果
[root@master demo]# kubectl logs pi-fd25w
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901
[root@master demo]# kubectl get job
NAME COMPLETIONS DURATION AGE
pi 1/1 10s 5m8s
//清除job资源
[root@master demo]# kubectl delete -f job.yaml
job.batch "pi" deleted
5 . CronJob 控制器
周期性任务，像Linux的Crontab一样。
周期性任务
应用场景：通知，备份
https://kubernetes.io/docs/tasks/job/automated-tasks-with-cron-jobs/
示例：
//每分钟打印hello
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: hello
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: hello
image: busybox
args:
- /bin/sh
- -c
- date; echo Hello from the Kubernetes cluster
restartPolicy: OnFailure
[root@master demo]# kubectl create -f cronjob.yaml
cronjob.batch/hello created
[root@master demo]# kubectl get pods
NAME READY STATUS RESTARTS AGE
dns-test 1/1 Running 0 46m
nginx-deployment-7gvsx 1/1 Running 0 19m
nginx-deployment-qgzgm 1/1 Running 0 19m
[root@master demo]# kubectl get cronjob
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
hello */1 * * * * False 0 <none> 34s
[root@master demo]#
查看执行结果
[root@master demo]# kubectl logs hello-1602687420-l5qkh
Wed Oct 14 14:57:04 UTC 2020
Hello from the Kubernetes cluster
//等待一分钟后又会再执行一次，计划任务生效
[root@master demo]# kubectl get pods -w
NAME READY STATUS RESTARTS AGE
dns-test 1/1 Running 0 48m
hello-1602687360-dz8gg 0/1 Completed 0 99s
hello-1602687420-l5qkh 0/1 Completed 0 39s