文章目錄
一：k8s的五種控制器
1.1：k8s的控制器類型
- Kubernetes中內建了很多controller（控制器），這些相當於一個狀態機，用來控制Pod的具體狀態和行爲
1、deployment：適合無狀態的服務部署
2、StatefullSet：適合有狀態的服務部署
3、DaemonSet：一次部署，所有的node節點都會部署，例如一些典型的應用場景：
- 運行集羣存儲 daemon，例如在每個Node上運行 glusterd、ceph
- 在每個Node上運行日誌收集 daemon，例如 fluentd、 logstash
- 在每個Node上運行監控 daemon，例如 Prometheus Node Exporter
4、Job：一次性的執行任務
5、Cronjob：週期性的執行任務
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控制器又被稱爲工作負載，pod通過控制器實現應用的運維，比如伸縮、升級等
1.2：Deployment控制器
- 適合部署無狀態的應用服務，用來管理pod和replicaset，具有上線部署、副本設定、滾動更新、回滾等功能，還可提供聲明式更新，例如只更新一個新的Image
1.2.1：測試deployment控制器
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1、編寫yaml文件，並創建nginx服務pod資源
[root@master test]# vim nginx-deployment.yaml apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deployment labels: app: nginx spec: replicas: 3 '//指定副本數爲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 '//創建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 '//可以查看所有類型的pod資源' 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、查看控制器參數：可以使用describe或者edit兩種方式
[root@master test]# kubectl describe deploy nginx-deployment '//或者使用edit' [root@master test]# kubectl edit deploy nginx-deployment '//兩種方式都可以查看pod的更詳細的信息，包括各種類型的名稱、資源、事件等' ...省略內容 strategy: rollingUpdate: '//此段解釋的是滾動更新機制' maxSurge: 25% '//25%指的是pod數量的百分比，最多可以擴容125%' maxUnavailable: 25% '//25%指的是pod數量的百分比，最多可以縮容75%' type: RollingUpdate ...省略內容 -
3、查看控制器的歷史版本，滾動更新以此爲基礎
[root@master test]# kubectl rollout history deploy/nginx-deployment deployment.extensions/nginx-deployment REVISION CHANGE-CAUSE 1 <none> '//發現只有一個，說明沒有開始滾動更新，否則會保持2個'
1.3：SatefulSet控制器
1、適合部署有狀態應用
2、解決Pod的獨立生命週期，保持Pod啓動順序和唯一性
3、穩定，唯一的網絡標識符，持久存儲（例如：etcd配置文件，節點地址發生變化，將無法使用）
4、有序，優雅的部署和擴展、刪除和終止（例如：mysql主從關係，先啓動主，再啓動從）
5、有序，滾動更新
6、應用場景：例如數據庫
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無狀態服務的特點：
1）deployment 認爲所有的pod都是一樣的
2）不用考慮順序的要求
3）不用考慮在哪個node節點上運行
4）可以隨意擴容和縮容
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有狀態服務的特點：
1）實例之間有差別，每個實例都有自己的獨特性，元數據不同，例如etcd，zookeeper
2）實例之間不對等的關係，以及依靠外部存儲的應用。
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常規的service服務和無頭服務的區別
service：一組Pod訪問策略，提供cluster-IP羣集之間通訊，還提供負載均衡和服務發現。
Headless service 無頭服務，不需要cluster-IP，直接綁定具體的Pod的IP，無頭服務經常用於statefulset的有狀態部署
1.3.1：創建無頭服務的service資源和dns資源
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由於有狀態服務的IP地址是動態的，所以使用無頭服務的時候要綁定dns服務
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1、編寫yaml文件並創建service資源
[root@master test]# vim nginx-headless.yaml apiVersion: v1 kind: Service '//創建一個service類型的資源' 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資源' 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 '//剛剛創建的無頭服務沒有clusterIP' -
2、配置dns服務，使用yaml文件創建
[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 '//系統賬戶，爲pod中的進程和外部用戶提供身份信息' metadata: name: coredns namespace: kube-system '//指定名稱空間' labels: kubernetes.io/cluster-service: "true" addonmanager.kubernetes.io/mode: Reconcile --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole '//創建訪問權限的角色' 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 '//創建集羣角色綁定的用戶' 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 '//通過此服務來更改服務發現的工作方式' 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名稱空間的pod和svc資源' 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、創建一個測試的pod資源並驗證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：創建statefulset資源
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1、編寫yaml文件並創建資源
[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 '//指定爲無頭服務' selector: app: nginx --- apiVersion: apps/v1beta1 kind: StatefulSet metadata: name: nginx-statefulset namespace: default spec: serviceName: nginx replicas: 3 '//指定副本數量' 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 '//創建用來測試dns的pod資源' 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 . '//先刪除之前所有的資源' -
2、創建資源並測試
[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 '//登陸pod資源進行測試' / # 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 -
相比於Deployment而言，StatefulSet是有身份的！（序列編號區分唯一身份）
身份三要素：
1、域名 nginx-statefulset-0.nginx
2、主機名 nginx-statefulset-0
3、存儲(PVC)
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StatefulSet的有序部署和有序伸縮
有序部署（即0到N-1）
有序收縮，有序刪除（即從N-1到0）
無論是部署還是刪除，更新下一個 Pod 前，StatefulSet 控制器終止每個 Pod 並等待它們變成 Running 和 Ready。
1.4：DaemonSet控制器
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在每一個Node上運行一個Pod
新加入的Node也同樣會自動運行一個Pod
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應用場景：監控，分佈式存儲，日誌收集等
1.4.1：測試
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1、編寫yaml文件並創建資源
[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、查看資源的部署情況
[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> '//發現daemonset的資源已經分配到兩個node節點上了'
1.5：job控制器
- 一次性執行任務，類似Linux中的job
- 應用場景：如離線數據處理，視頻解碼等業務
1.5.1：測試
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1、編寫yaml文件並創建資源
[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)"] '//命令是計算π的值' restartPolicy: Never backoffLimit: 4 '//重試次數默認是6次，修改爲4次，當遇到異常時Never狀態會重啓，所以要設定次數。' [root@master test]# kubectl create -f job-test.yaml job.batch/pi created -
2、查看job資源
[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 '//執行成功後就結束了' ^C[root@master test]# kubectl logs pi-dhzrg '//查看日誌可以查看結果' 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901 -
3、查看並刪除job資源
[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
- 週期性任務，像Linux的Crontab一樣。
- 應用場景：如通知，備份等
1.6.1：測試
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1、編寫yaml文件並創建資源（建立每分鐘打印hello的任務）
[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資源
[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、可以查看日誌信息
^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，用完之後要刪掉，不然會佔用很多資源'