kubernetes-----控制器
一.控制器概述
- 控制器：又称之为工作负载，分别包含以下类型的控制器，控制器决定资源的类型
1.Deployment
2.StatefulSet
3.DaemonSet
4.Job
5.CronJob
-
pod与控制器之间的关系
控制器：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，比如伸缩，升级等
二.Deployment
- 使用deployment部署无状态应用；管理pod和ReplicaSet（副本数）；具有线上部署、副本设定、滚动升级、回滚等功能；提供声明式更新，例如只更新一个新的image，更新相当于灰度部署。
- 应用场景为：web服务部署
无状态：
deployment认为所有的pod都是一样的
不用考虑顺序的要求
不用考虑在哪个node节点上运行
可以随意扩容和缩容
创建实例
- 创建pod资源
[root@master demo]# cat nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3 ##设定副本数为3，回滚操作通过控制副本数来实现
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 create -f nginx-deployment.yaml
deployment.apps/nginx-deployment created
[root@master demo]#
-
查看pod资源，deploy控制器，副本数
##rs是replicaset的缩写
[root@master demo]# kubectl get pods,deploy,rs
NAME READY STATUS RESTARTS AGE
pod/nginx-deployment-d55b94fd-54cpg 1/1 Running 0 6m57s
pod/nginx-deployment-d55b94fd-fpq25 1/1 Running 0 6m57s
pod/nginx-deployment-d55b94fd-hnxdc 1/1 Running 0 6m57s
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
deployment.extensions/nginx-deployment 3 3 3 3 6m57s
NAME DESIRED CURRENT READY AGE
replicaset.extensions/nginx-deployment-d55b94fd 3 3 3 6m57s
[root@master demo]#
-
查看控制器，使得控制器以yaml的文件格式输出
[root@master demo]# kubectl get deployment.extensions/nginx-deployment -o yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "1"
creationTimestamp: 2020-05-19T14:06:14Z
generation: 1
labels:
app: nginx
name: nginx-deployment
namespace: default
resourceVersion: "416373"
selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/nginx-deployment
uid: e6835a1d-99d9-11ea-bb1a-000c29ce5f24
spec:
progressDeadlineSeconds: 600
replicas: 3 ##副本数控制资源总量
revisionHistoryLimit: 10
selector:
matchLabels:
app: nginx
strategy: ##控制滚动更新的策略
rollingUpdate:
maxSurge: 25% ##表示更新后创建资源25%，一共不超过125%的容量
maxUnavailable: 25% ##释放资源最大为25%
type: RollingUpdate
template:
metadata:
creationTimestamp: null
labels:
app: nginx
spec:
containers:
- image: nginx:1.15.4
imagePullPolicy: IfNotPresent ##默认的镜像来去策略，表示有镜像，则不下载
name: nginx
ports:
- containerPort: 80
protocol: TCP
resources: {}
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
status:
availableReplicas: 3
conditions:
- lastTransitionTime: 2020-05-19T14:06:17Z
lastUpdateTime: 2020-05-19T14:06:17Z
message: Deployment has minimum availability.
reason: MinimumReplicasAvailable
status: "True"
type: Available
- lastTransitionTime: 2020-05-19T14:06:14Z
lastUpdateTime: 2020-05-19T14:06:17Z
message: ReplicaSet "nginx-deployment-d55b94fd" has successfully progressed.
reason: NewReplicaSetAvailable
status: "True"
type: Progressing
observedGeneration: 1
readyReplicas: 3
replicas: 3
updatedReplicas: 3
[root@master demo]# - 查看滚动的历史版本
##只有一行数据表示此前没有进行过更新回滚操作
[root@master demo]# kubectl rollout history deploy/nginx-deployment
deployment.extensions/nginx-deployment
REVISION CHANGE-CAUSE
1
[root@master demo]# 三.StatefulSet
- 部署有状态的应用；
- 解决pod独立生命周期，保持Pod的启动顺序和唯一性；
- 稳定，唯一性的网络标识符，持久存储（例如：etcd配置文件，节点地址变化，将无法使用）
- 有序，优雅的部署和扩展、删除和终止（例如：mysql的主从关系、先启动主，再启动从）有序，滚动更新。
- 应用场景为：数据库
有状态：
实例之间有差异，每个实例都有自己的独特性，元数据不同，例如etcd，zookeeper
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Headless service的区别
- 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，直接半丁具体的Pod的IP
StatefulSet控制器使用实例
- 创建服务资源
[root@master demo]# cat 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
[root@master demo]# kubectl create -f nginx-service.yaml
service/nginx-service created
[root@master demo]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.0.0.1 443/TCP 22d
nginx-service NodePort 10.0.0.178 80:40715/TCP 8s
[root@master demo]#
-
创建headless service资源
[root@master demo]# cat headless.yaml
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
ports:
- port: 80
name: web
clusterIP: None
selector:
app: nginx
[root@master demo]# kubectl apply -f headless.yaml
service/nginx created
[root@master demo]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.0.0.1 443/TCP 22d
nginx ClusterIP None 80/TCP 8s
nginx-service NodePort 10.0.0.178 80:40715/TCP 16m
[root@master demo]#
-
创建DNS解析的资源
[root@master demo]# cat coredns.yaml
# Warning: This is a file generated from the base underscore template file: coredns.yaml.base
apiVersion: v1
kind: ServiceAccount
metadata:
name: coredns
namespace: kube-system
labels:
kubernetes.io/cluster-service: "true"
addonmanager.kubernetes.io/mode: Reconcile
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
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
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
metadata:
name: coredns
namespace: kube-system
labels:
addonmanager.kubernetes.io/mode: EnsureExists
data:
Corefile: |
.: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
[root@master demo]# 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
[root@master demo]#
- 验证DNS解析
##清楚当前目录下与yaml文件相关得资源
[root@master demo]# kubectl delete -f .
。。。
[root@master demo]# kubectl get pods
No resources found.
[root@master demo]# 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
[root@master demo]# kubectl create -f sts.yaml
service/nginx created
statefulset.apps/nginx-statefulset created
[root@master demo]# cat pod3.yaml
apiVersion: v1
kind: Pod
metadata:
name: dns-test
spec:
containers:
- name: busybox
image: busybox:1.28.4
args:
- /bin/sh
- -c
- sleep 6000
restartPolicy: Never
[root@master demo]# kubectl create -f pod3.yaml
pod/dns-test created
[root@master demo]# kubectl get pod,svc
NAME READY STATUS RESTARTS AGE
pod/dns-test 1/1 Running 0 74s
pod/nginx-statefulset-0 1/1 Running 0 97s
pod/nginx-statefulset-1 1/1 Running 0 75s
pod/nginx-statefulset-2 1/1 Running 0 54s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.0.0.1 443/TCP 22d
service/nginx ClusterIP None 80/TCP 97s
[root@localhost 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: 172.17.42.2 nginx-statefulset-0.nginx.default.svc.cluster.local
注：Deployment和StatefulSet的区别是，StatefulSet创建的资源是有身份的
身份的三要素为：
域名：nginx-statefulset-0.nginx
主机名：nginx-statefulset-0
存储：PVC
四.DaemonSet
- 在每一个Node上面运行一个Pod；新加入的Node也同样会自动运行一个Pod
- 应用场景为：Agent
实例如下
五.Jod和CronJob
- Job：普通任务，一次性执行。应用场景为：离线数据处理，视频解码等业务
- CronJob：周期任务，按时执行。应用场景：通知备份等
Job实例如下
- 创建实例资源，
[root@master demo]# cat 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
backoffLimit: 4 ##重试默认次数为4次，当遇到异常时Never状态会重启，所以要设定次数。
[root@master demo]# kubectl create -f job.yaml
job.batch/pi created
[root@master demo]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx-deployment-pk572 1/1 Running 0 12m
nginx-deployment-rzxdh 1/1 Running 0 12m
pi-qpn8l 0/1 Completed 0 59s
[root@master demo]#
- 打印日志
[root@master demo]# kubectl logs pi-qpn8l
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901
[root@master demo]#
CronJob实例如下
##每一分钟都在日志上打印一个hello
[root@master demo]# cat cronjob.yaml
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 cronjob
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
hello */1 * * * * False 0 12s
[root@master demo]# kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-1589904720-k4ssh 0/1 ContainerCreating 0 9s
[root@master demo]# kubectl logs hello-1589904720-k4ssh
Tue May 19 16:12:11 UTC 2020
Hello from the Kubernetes cluster
[root@master demo]# kubectl get cronjob
NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE
hello */1 * * * * False 0 42s 54s
[root@master demo]#
注：cronjob会不停地创建pod资源，所以测试之后建议删除