k8s，盘他！k8s的五种控制器类型解析

女爷i 2023-02-10 05:14 18阅读 0赞

### 文章目录 ###

*  一：k8s的五种控制器
 *   *   *  1.1：k8s的控制器类型
         *  1.2：Deployment控制器
         *   *   *  1.2.1：测试deployment控制器
         *  1.3：SatefulSet控制器
         *   *   *  1.3.1：创建无头服务的service资源和dns资源
                 *  1.3.2：创建statefulset资源
         *  1.4：DaemonSet控制器
         *   *   *  1.4.1：测试
         *  1.5：job控制器
         *   *   *  1.5.1：测试
         *  1.6：cronjob控制器
         *   *   *  1.6.1：测试
         *  如有疑问可评论区交流！

# 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
    
    ![mark][]

### 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
    
    > 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。

### 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'

### 如有疑问可评论区交流！ ###

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