K8s五种控制器

k8s的控制器类型

Kubernetes中内建了很多controller（控制器），这些相当于一个状态机，用来控制Pod的具体状态和行为
deployment：适合无状态的服务部署
StatefullSet：适合有状态的服务部署
DaemonSet：一次部署，所有的node节点都会部署，例如一些典型的应用场景：
运行集群存储 daemon，例如在每个Node上运行 glusterd、ceph
在每个Node上运行日志收集 daemon，例如 fluentd、 logstash
在每个Node上运行监控 daemon，例如 Prometheus Node Exporter
Job：一次性的执行任务
Cronjob：周期性的执行任务

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

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

[root@localhost bate3]# vim nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment	##控制器类型
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

[root@localhost bate3]# kubectl create -f nginx-deployment.yaml 
deployment.apps/nginx-deployment created
[root@localhost bate3]# kubectl get pod -w
NAME                                READY   STATUS              RESTARTS   AGE
nginx-deployment-78cdb5b557-g42hm   0/1     ContainerCreating   0          19s
nginx-deployment-78cdb5b557-rbpgh   0/1     ContainerCreating   0          19s
nginx-deployment-78cdb5b557-zt2ld   1/1     Running             0          19s
nginx-deployment-78cdb5b557-rbpgh   1/1   Running   0     60s
nginx-deployment-78cdb5b557-g42hm   1/1   Running   0     81s

查看控制器参数：可以使用describe或者edit两种方式

[root@master test]# kubectl describe deploy nginx-deployment
##或者使用edit
[root@master test]# kubectl edit deploy nginx-deployment
##两种方式都可以查看pod的更详细的信息，包括各种类型的名称、资源、事件等
    ...省略内容
  strategy:
    rollingUpdate:		##此段解释的是滚动更新机制'
      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%
    type: RollingUpdate
    …省略内容

SatefulSet控制器

1、适合部署有状态应用
2、解决Pod的独立生命周期，保持Pod启动顺序和唯一性
3、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）
4、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）
5、有序，滚动更新
6、应用场景：例如数据库

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。

常规的service服务和无头服务的区别
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，直接绑定具体的Pod的IP，无头服务经常用于statefulset的有状态部署

创建无头服务的service资源和dns资源

由于有状态服务的IP地址是动态的，所以使用无头服务的时候要绑定dns服务

编写yaml文件并创建service资源

[root@localhost bate3]# vim nginx-headless.yaml
apiVersion: v1
kind: Service	##创建一个service类型的资源
metadata:
  name: nginx-headless
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None	##不使用clusterIP
  selector:
    app: nginx

[root@localhost bate3]# kubectl create -f nginx-headless.yaml 
service/nginx-headless created
[root@localhost bate3]# kubectl get svc
NAME             TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
http-service     NodePort    10.0.0.138   <none>        80:42018/TCP   2d9h
kubernetes       ClusterIP   10.0.0.1     <none>        443/TCP        14d
mytomcat         NodePort    10.0.0.61    <none>        80:30800/TCP   43h
nginx-headless   ClusterIP   None         <none>        80/TCP         7s 

配置dns服务，使用yaml文件创建

[root@localhost bate3]# 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


[root@localhost bate3]# 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@localhost bate3]# kubectl get svc,pod -n kube-system
NAME                           TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)         AGE
service/kube-dns               ClusterIP   10.0.0.2     <none>        53/UDP,53/TCP   28s
service/kubernetes-dashboard   NodePort    10.0.0.238   <none>        443:30001/TCP   6d

NAME                                        READY   STATUS    RESTARTS   AGE
pod/coredns-56684f94d6-bpszw                1/1     Running   0          28s
pod/kubernetes-dashboard-7dffbccd68-wc77c   1/1     Running   1          2d

创建一个测试的pod资源并验证DNS解析

[root@localhost bate3]# kubectl run -it --image=busybox:1.28.4 --rm --restart=Never sh
If you don't see a command prompt, try pressing enter.
/ # 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

/ # exit
pod "sh" deleted

创建statefulset资源

[root@localhost bate3]# vim statefulset-test.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None	##指定为无头服务
  selector:
    app: nginx
---
apiVersion: apps/v1beta1  
kind: StatefulSet  
metadata:
  name: nginx-statefulset  
  namespace: default
spec:
  serviceName: nginx  
  replicas: 3  ##指定副本数量
  selector:
    matchLabels:  
       app: nginx
  template:  
    metadata:
      labels:
        app: nginx  
    spec:
      containers:
      - name: nginx
        image: nginx:latest  
        ports:
        - containerPort: 80 

[root@localhost bate3]# vim pod-dns-test.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

[root@localhost bate3]# mv coredns.yaml /
[root@localhost bate3]# ls
nginx-deployment.yaml  nginx-headless.yaml  pod-dns-test.yaml  statefulset-test.yaml
[root@localhost bate3]# kubectl delete -f .
deployment.apps "nginx-deployment" deleted
service "nginx-headless" deleted
Error from server (NotFound): error when deleting "pod-dns-test.yaml": pods "dns-test" not found
Error from server (NotFound): error when deleting "statefulset-test.yaml": services "nginx" not found
Error from server (NotFound): error when deleting "statefulset-test.yaml": statefulsets.apps "nginx-statefulset" not found
[root@localhost bate3]# mv /coredns.yaml /bate3

创建资源并测试

[root@localhost bate3]# kubectl apply -f coredns.yaml
serviceaccount/coredns unchanged
clusterrole.rbac.authorization.k8s.io/system:coredns unchanged
clusterrolebinding.rbac.authorization.k8s.io/system:coredns unchanged
configmap/coredns unchanged
deployment.extensions/coredns unchanged
service/kube-dns unchanged
[root@localhost bate3]# kubectl create -f statefulset-test.yaml 
service/nginx created
statefulset.apps/nginx-statefulset created
[root@localhost bate3]# kubectl create -f pod-dns-test.yaml 
pod/dns-test created

[root@localhost bate3]# kubectl get svc,pods
NAME                   TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
service/http-service   NodePort    10.0.0.138   <none>        80:42018/TCP   2d9h
service/kubernetes     ClusterIP   10.0.0.1     <none>        443/TCP        14d
service/mytomcat       NodePort    10.0.0.61    <none>        80:30800/TCP   43h
service/nginx          ClusterIP   None         <none>        80/TCP         68s

NAME                      READY   STATUS    RESTARTS   AGE
pod/dns-test              1/1     Running   0          15s
pod/nginx-statefulset-0   1/1     Running   0          68s
pod/nginx-statefulset-1   1/1     Running   0          61s
pod/nginx-statefulset-2   1/1     Running   0          50s

[root@master test]# kubectl exec -it dns-test sh	##登陆pod资源进行测试
/ # 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: 172.17.45.2 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: 172.17.9.2 nginx-statefulset-1.nginx.default.svc.cluster.local

/ # exit

相比于Deployment而言，StatefulSet是有身份的！（序列编号区分唯一身份）
身份三要素：
1、域名 nginx-statefulset-0.nginx
2、主机名 nginx-statefulset-0
3、存储(PVC)

StatefulSet的有序部署和有序伸缩
有序部署（即0到N-1）
有序收缩，有序删除（即从N-1到0）
无论是部署还是删除，更新下一个 Pod 前，StatefulSet 控制器终止每个 Pod 并等待它们变成 Running 和 Ready。

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：监控，分布式存储，日志收集等

编写yaml文件并创建资源测试

[root@localhost bate3]# vim daemonset-test.yaml
apiVersion: apps/v1
kind: DaemonSet 
metadata:
  name: nginx-daemonset
  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

查看资源的部署情况

[root@localhost bate3]# vim daemonset-test.yaml
[root@localhost bate3]# kubectl create -f daemonset-test.yaml 
daemonset.apps/nginx-daemonset created
[root@localhost bate3]# kubectl get pod -o wide
NAME                    READY   STATUS    RESTARTS   AGE     IP            NODE       NOMINATED NODE
dns-test                1/1     Running   0          8m24s   172.17.9.5    20.0.0.5   <none>
nginx-daemonset-4whnb   1/1     Running   0          4s      172.17.45.4   20.0.0.4   <none>
nginx-daemonset-6glzs   1/1     Running   0          4s      172.17.9.6    20.0.0.5   <none>
……略

job控制器

一次性执行任务，类似Linux中的job
应用场景：如离线数据处理，视频解码等业务

编写yaml文件并创建资源

[root@localhost bate3]# vim job-test.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)"]		##命令是计算π的值
      restartPolicy: Never
  backoffLimit: 4		##重试次数默认是6次，修改为4次，当遇到异常时Never状态会重启，所以要设定次数。
[root@localhost bate3]# kubectl create -f job-test.yaml 
job.batch/pi created

查看job资源

[root@master test]# kubectl get pod -w
NAME                    READY   STATUS              RESTARTS   AGE
dns-test                1/1     Running             0          23m
nginx-daemonset-m8lm5   1/1     Running             0          5m33s
nginx-daemonset-sswfq   1/1     Running             0          5m33s
nginx-statefulset-0     1/1     Running             0          23m
nginx-statefulset-1     1/1     Running             0          23m
nginx-statefulset-2     1/1     Running             0          23m
pi-dhzrg                0/1     ContainerCreating   0          50s
pi-dhzrg   1/1   Running   0     61s
pi-dhzrg   0/1   Completed   0     65s	##执行成功后就结束了
^C
[root@master test]# kubectl logs pi-dhzrg	'//查看日志可以查看结果'
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901

查看并删除job资源

^C[root@localhost bate3]# kubectl delete -f job-test.yaml 
job.batch "pi" deleted
[root@localhost bate3]# kubectl get job
No resources found.

cronjob控制器

周期性任务，像Linux的Crontab一样。
应用场景：如通知，备份等

编写yaml文件并创建资源

建立每分钟打印hello的任务

[root@localhost bate3]# vim cronjob-test.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		##异常退出时重启

[root@localhost bate3]# kubectl create -f cronjob-test.yaml 
cronjob.batch/hello created

查看pod资源

[root@localhost bate3]# kubectl get pod -w
NAME                    READY   STATUS    RESTARTS   AGE
……略
hello-1602725700-tp7kw   0/1   Pending   0     0s
hello-1602725700-tp7kw   0/1   Pending   0     0s
hello-1602725700-tp7kw   0/1   ContainerCreating   0     0s
hello-1602725700-tp7kw   0/1   Completed   0     4s
hello-1602725760-gtxbv   0/1   Pending   0     0s
hello-1602725760-gtxbv   0/1   Pending   0     0s
hello-1602725760-gtxbv   0/1   ContainerCreating   0     0s
hello-1602725760-gtxbv   0/1   Completed   0     2s
……略

查看日志信息

[root@localhost bate3]# kubectl logs hello-1602725700-tp7kw
Thu Oct 15 01:35:04 UTC 2020
Hello from the Kubernetes cluster
[root@localhost bate3]# kubectl logs hello-1602725760-gtxbv
Thu Oct 15 01:36:01 UTC 2020
Hello from the Kubernetes cluster

记得删除，不然容易吃资源
[root@localhost bate3]# kubectl delete -f cronjob-test.yaml 
cronjob.batch "hello" deleted