前言

Pod通过控制器实现应用的运维，如伸缩、升级等，控制器决定了创建pod资源的方式和类型，在集群上管理和运行容器的对象通过label-selector 相关联。
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

一：k8s的五种控制器

1.1：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

1、deployment：适合无状态的服务部署
2、StatefullSet：适合有状态的服务部署
3、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
4、Job：一次性的执行任务
5、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
  

1.2：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

1.2.1：测试deployment控制器

• 1、编写yaml文件，并创建nginx服务pod资源

[root@master test]# 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
[root@master test]# kubectl create -f nginx-deployment.yaml 	'//创建pod'
deployment.apps/nginx-deployment created
[root@master test]# kubectl get pod -w
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-78cdb5b557-7tr9h   1/1     Running   0          13s
nginx-deployment-78cdb5b557-kbt7m   1/1     Running   0          13s
nginx-deployment-78cdb5b557-knd7n   1/1     Running   0          13s
^C[root@master test]# kubectl get all	'//可以查看所有类型的pod资源'
NAME                                    READY   STATUS    RESTARTS   AGE
pod/nginx-deployment-78cdb5b557-7tr9h   1/1     Running   0          44s
pod/nginx-deployment-78cdb5b557-kbt7m   1/1     Running   0          44s
pod/nginx-deployment-78cdb5b557-knd7n   1/1     Running   0          44s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.0.0.1     <none>        443/TCP   11d

NAME                               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-deployment   3         3         3            3           44s

NAME                                          DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-deployment-78cdb5b557   3         3         3       44s

• 2、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

• 3、查看控制器的历史版本，滚动更新以此为基础

[root@master test]# kubectl rollout history deploy/nginx-deployment
deployment.extensions/nginx-deployment 
REVISION  CHANGE-CAUSE
1         <none>	'//发现只有一个，说明没有开始滚动更新，否则会保持2个'

1.3：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

1.3.1：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
• 1、编写yaml文件并创建service资源

[root@master test]# 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@master test]# kubectl create -f nginx-headless.yaml 
service/nginx-headless created
[root@master test]# kubectl get svc		'//查看service资源'
NAME             TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes       ClusterIP   10.0.0.1     <none>        443/TCP   11d
nginx-headless   ClusterIP   None         <none>        80/TCP    19s	'//刚刚创建的无头服务没有clusterIP'

• 2、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
[root@master test]# 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 test]# kubectl get pod,svc -n kube-system	'//查看kube-system名称空间的pod和svc资源'
NAME                                        READY   STATUS    RESTARTS   AGE
pod/coredns-56684f94d6-8p44x                1/1     Running   0          30s
pod/kubernetes-dashboard-7dffbccd68-58qms   1/1     Running   2          11d

NAME                           TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)         AGE
service/kube-dns               ClusterIP   10.0.0.2     <none>        53/UDP,53/TCP   31s
service/kubernetes-dashboard   NodePort    10.0.0.139   <none>        443:30005/TCP   11d

• 3、创建一个测试的pod资源并验证DNS解析

[root@master test]#  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	'//解析成功'
/ # exit
pod "sh" deleted

1.3.2：创建statefulset资源

• 1、编写yaml文件并创建资源

[root@master test]# 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@master test]# vim pod-dns-test.yaml 	'//创建用来测试dns的pod资源'
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@master test]# kubectl delete -f .	'//先删除之前所有的资源'

• 2、创建资源并测试

[root@master test]# 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 test]# kubectl create -f statefulset-test.yaml 
service/nginx created
statefulset.apps/nginx-statefulset created
[root@master test]# kubectl create -f pod-dns-test.yaml 
pod/dns-test created
[root@master test]# kubectl get pod,svc
NAME                      READY   STATUS    RESTARTS   AGE
pod/dns-test              1/1     Running   0          37s
pod/nginx-statefulset-0   1/1     Running   0          56s
pod/nginx-statefulset-1   1/1     Running   0          39s
pod/nginx-statefulset-2   1/1     Running   0          21s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.0.0.1     <none>        443/TCP   12d
service/nginx        ClusterIP   None         <none>        80/TCP    56s
[root@master test]# kubectl exec -it dns-test sh	'//登陆pod资源进行测试'
/ # nslookup pod/nginx-statefulset-0
/ # 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-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: 172.17.78.2 nginx-statefulset-0.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

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

1.4：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

1.4.1：测试

• 1、编写yaml文件并创建资源

[root@master test]# 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
[root@master test]# kubectl create -f daemonset-test.yaml 
daemonset.apps/nginx-daemonset created

• 2、查看资源的部署情况

[root@master test]# kubectl get pod -o wide
NAME                    READY   STATUS    RESTARTS   AGE   IP            NODE              NOMINATED NODE
dns-test                1/1     Running   0          18m   172.17.14.4   192.168.233.133   <none>
nginx-daemonset-m8lm5   1/1     Running   0          41s   172.17.78.5   192.168.233.132   <none>
nginx-daemonset-sswfq   1/1     Running   0          41s   172.17.14.5   192.168.233.133   <none>
nginx-statefulset-0     1/1     Running   0          18m   172.17.78.2   192.168.233.132   <none>
nginx-statefulset-1     1/1     Running   0          18m   172.17.14.3   192.168.233.133   <none>
nginx-statefulset-2     1/1     Running   0          18m   172.17.78.4   192.168.233.132   <none>
'//发现daemonset的资源已经分配到两个node节点上了'

1.5：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

1.5.1：测试

• 1、编写yaml文件并创建资源

[root@master test]# 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@master test]# kubectl create -f job-test.yaml 
job.batch/pi created

• 2、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

• 3、查看并删除job资源

[root@master test]# kubectl get job
NAME   COMPLETIONS   DURATION   AGE
pi     1/1           65s        2m49s
[root@master test]# kubectl delete -f job-test.yaml 
job.batch "pi" deleted
[root@master test]# kubectl get job
No resources found.

1.6：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

1.6.1：测试

• 1、编写yaml文件并创建资源（建立每分钟打印hello的任务）

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

• 2、查看pod资源

[root@master test]# kubectl get pod -w
NAME                    READY   STATUS    RESTARTS   AGE
dns-test                1/1     Running   0          32m
nginx-daemonset-m8lm5   1/1     Running   0          14m
nginx-daemonset-sswfq   1/1     Running   0          14m
nginx-statefulset-0     1/1     Running   0          32m
nginx-statefulset-1     1/1     Running   0          32m
nginx-statefulset-2     1/1     Running   0          32m
hello-1589946540-6wn5h   0/1   Pending   0     0s
hello-1589946540-6wn5h   0/1   Pending   0     0s
hello-1589946540-6wn5h   0/1   ContainerCreating   0     0s
hello-1589946540-6wn5h   0/1   Completed   0     14s
hello-1589946600-dlt4c   0/1   Pending   0     0s
hello-1589946600-dlt4c   0/1   Pending   0     0s
hello-1589946600-dlt4c   0/1   ContainerCreating   0     0s
hello-1589946600-dlt4c   0/1   Completed   0     16s

• 3、可以查看日志信息

^C[root@master test]# kubectl logs hello-1589946540-6wn5h
Wed May 20 03:49:18 UTC 2020
Hello from the Kubernetes cluster
[root@master test]# kubectl logs hello-1589946600-dlt4c
Wed May 20 03:50:22 UTC 2020
Hello from the Kubernetes cluster
[root@master test]# kubectl delete -f cronjob-test.yaml 
cronjob.batch "hello" deleted	'//使用cronjob要慎重，用完之后要删掉，不然会占用很多资源'