kubernetes基本功能(Kubernetes副本机制篇)(1)

前言

在上文Kubernetes Pod操作篇介绍了Kubernetes的核心组件Pod,本文继续介绍kubernetes的副本机制,正是因为副本机制你的部署能自动保待运行,并且保持健康,无须任何手动干预。

探针

kubernetes可以通过存活探针(liveness probe)检查容器是否还在运行。可以为pod中的每个容器单独指定存活探针;如果探测失败,kubernetes将定期执行探针并重新启动容器;
kubernetes有以下三种探测容器的机制:

1.准备镜像

1.1 准备App.js

为了测试探针的作用,需要准备新的镜像;在之前的服务中稍作改动,在第五个请求之后,给每个请求返回HTTP状态码500(Internal Server Error),app.js做如下改动:

const http = require('http'); const os = require('os'); console.log("kubia server is starting..."); var requestCount = 0; var handler = function(request,response){ console.log("Received request from " request.connection.remoteAddress); requestCount ; if (requestCount > 5) { response.writeHead(500); response.end("I'm not well. Please restart me!"); return; } response.writeHead(200); response.end("You've hit " os.hostname() "\n"); }; var www = http.createServer(handler); www.listen(8080);

requestCount记录请求的次数,大于5次直接返回500状态码,这样探针可以捕获状态码进行服务器重启;

1.2 构建镜像

[root@localhost unhealthy]# docker build -t kubia-unhealthy . Sending build context to Docker daemon 3.584kB Step 1/3 : FROM node:7 ---> d9aed20b68a4 Step 2/3 : ADD app.js /app.js ---> e9e1b44f8f54 Step 3/3 : ENTRYPOINT ["node","app.js"] ---> Running in f58d6ff6bea3 Removing intermediate container f58d6ff6bea3 ---> d36c6390ec66 Successfully built d36c6390ec66 Successfully tagged kubia-unhealthy:latest

通过docker build构建kubia-unhealthy镜像

1.3 推送镜像

[root@localhost unhealthy]# docker tag kubia-unhealthy ksfzhaohui/kubia-unhealthy [root@localhost unhealthy]# docker login Authenticating with existing credentials... WARNING! Your password will be stored unencrypted in /root/.docker/config.json. Configure a credential helper to remove this warning. See https://docs.docker.com/engine/reference/commandline/login/#credentials-store Login Succeeded [root@localhost unhealthy]# docker push ksfzhaohui/kubia-unhealthy The push refers to repository [docker.io/ksfzhaohui/kubia-unhealthy] 40d9e222a827: Pushed ...... latest: digest: sha256:5fb3ebeda7f98818bc07b2b1e3245d6a21014a41153108c4dcf52f2947a4dfd4 size: 2213

首先给镜像附加标签,然后登录docker hub,最后推送到docker hub:

kubernetes基本功能(Kubernetes副本机制篇)(2)

2.探针实战

2.1 Http探针yaml文件

创建YAML描述文件,指定了一个Http Get存活探针,告诉Kubernetes定期在端口路径下执行Http Get请求,以确定容器是否健康;

apiVersion: v1 kind: Pod metadata: name: kubia-liveness spec: containers: - image: ksfzhaohui/kubia-unhealthy name: kubia livenessProbe: httpGet: path: / port: 8080

2.2 创建Pod

[d:\k8s]$ kubectl create -f kubia-liveness-probe.yaml pod/kubia-liveness created [d:\k8s]$ kubectl get pods NAME READY STATUS RESTARTS AGE kubia-liveness 0/1 ContainerCreating 0 3s

创建名称为kubia-liveness的Pod,查看的RESTARTS为0,隔一段时间再次观察:

[d:\k8s]$ kubectl get pods NAME READY STATUS RESTARTS AGE kubia-liveness 1/1 Running 2 4m

观察可以发现此时的RESTARTS=2,表示重启了2次,因为每次探测都会发送http请求,而服务在接收5次请求之后会返回500状态码,Kubernetes探测之后就会重启容器;

2.3 Pod探针描述

[d:\k8s]$ kubectl describe po kubia-liveness Name: kubia-liveness ...... State: Running Started: Mon, 23 Dec 2019 15:42:45 0800 Last State: Terminated Reason: Error Exit Code: 137 Started: Mon, 23 Dec 2019 15:41:15 0800 Finished: Mon, 23 Dec 2019 15:42:42 0800 Ready: True Restart Count: 2 Liveness: http-get http://:8080/ delay=0s timeout=1s period=10s #success=1 #failure=3 ...... Events: Type Reason Age From Message ---- ------ ---- ---- ------- ...... Warning Unhealthy 85s (x9 over 5m5s) kubelet, minikube Liveness probe failed: HTTP probe failed with statuscode: 500 Normal Killing 85s (x3 over 4m45s) kubelet, minikube Container kubia failed liveness probe, will be restarted ......

State:当前状态是运行中;
Last State:最后的状态是终止,原因是出现了错误,退出代码为137有特殊的含义:表示该进程由外部信号终止,数字137是两个数字的总和:128 x, 其中x是终止进程的信号编号,这里x=9是SIGKILL的信号编号,意味着这个进程被强行终止;
Restart Count:重启的次数;
Liveness:存活探针的附加信息,delay(延迟)、timeout(超时)、period(周期);大致意思就是开始探测延迟为0秒,探测超时时间为1秒,每隔10秒检测一次,探测连续失败三次重启容器;定义探针时可以自定义这些参数,比如initialDelaySeconds设置初始延迟等;
Events:列出了发生的事件,比如探测到失败,杀进程,重启容器等;

3.探针总结

首先生产环境运行的pod一定要配置探针;其次探针一定要检查程序的内部,不受外部因数影响比如外部服务,数据库等;最后就是探针应该足够轻量。
以上方式创建的pod,kubernetes在使用探针发现服务不可能就会重启服务,这项任务由承载pod的节点上的Kubelet执行,在主服务器上运行的Kubernetes Control Plane组件不会参与此过程;但如果节点本身崩溃,由于Kubelet本身运行在节点上,所以如果节点异常终止,它将无法执行任何操作,这时候就需要ReplicationController或类似机制管理pod。

ReplicationController

ReplicationController是一种kubernetes资源,可确保它的pod始终保持运行状态;如果pod因任何原因消失(包括节点崩溃),则ReplicationController会重新创建Pod;
ReplicationController会持续监控正在运行的pod列表,是确保pod的数量始终与其标签选择器匹配,一个ReplicationController有三个主要部分:

以上三个属性可以随时修改,但是只有副本个数修改对当前pod会有影响,比如当前副本数量减少了,那当前pod有可能会被删除;ReplicationController提供的好处:

1.创建ReplicationController

apiVersion: v1 kind: ReplicationController metadata: name: kubia spec: replicas: 3 selector: app: kubia template: metadata: labels: app: kubia spec: containers: - name: kubia image: ksfzhaohui/kubia ports: - containerPort: 8080

指定了类型为ReplicationController,名称为kubia;replicas设置副本为3,selector为标签选择器,template为pod创建的模版,三个要素都指定了,执行创建命令:

[d:\k8s]$ kubectl create -f kubia-rc.yaml replicationcontroller/kubia created [d:\k8s]$ kubectl get pods NAME READY STATUS RESTARTS AGE kubia-dssvz 1/1 Running 0 73s kubia-krlcr 1/1 Running 0 73s kubia-tg29c 1/1 Running 0 73s

创建完之后等一会执行获取pod列表可以发现创建了三个容器,删除其中一个,再次观察:

[d:\k8s]$ kubectl delete pod kubia-dssvz pod "kubia-dssvz" deleted [d:\k8s]$ kubectl get pods NAME READY STATUS RESTARTS AGE kubia-dssvz 1/1 Terminating 0 2m2s kubia-krlcr 1/1 Running 0 2m2s kubia-mgz64 1/1 Running 0 11s kubia-tg29c 1/1 Running 0 2m2s

被删除的pod结束中,新的pod已经启动,获取有关ReplicationController的信息:

[d:\k8s]$ kubectl get rc NAME DESIRED CURRENT READY AGE kubia 3 3 3 4m20s

期望3个副本,当前3个副本,准备好的也是3个,更详细的可以使用describe命令:

[d:\k8s]$ kubectl describe rc kubia Name: kubia Namespace: default Selector: app=kubia Labels: app=kubia Annotations: <none> Replicas: 3 current / 3 desired Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed Pod Template: ...... Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal SuccessfulCreate 5m20s replication-controller Created pod: kubia-dssvz Normal SuccessfulCreate 5m20s replication-controller Created pod: kubia-tg29c Normal SuccessfulCreate 5m20s replication-controller Created pod: kubia-krlcr Normal SuccessfulCreate 3m29s replication-controller Created pod: kubia-mgz64 Normal SuccessfulCreate 75s replication-controller Created pod: kubia-vwnmf

Replicas显示副本期望数和当前数,Pods Status显示每种状态下的副本数,最后的Events为发生的事件,测试一共删除2个pod,可以看到一个创建了5个pod;

注:因为使用的是Minikube,只有一个节点同时充当主节点和工作节点,节点故障无法模拟。

2.修改标签

通过更改pod的标签,可以将它从ReplicationController的作用域中添加或删除:

[d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-mgz64 1/1 Running 0 27m app=kubia kubia-tg29c 1/1 Running 0 28m app=kubia kubia-vwnmf 1/1 Running 0 24m app=kubia [d:\k8s]$ kubectl label pod kubia-mgz64 app=foo --overwrite pod/kubia-mgz64 labeled [d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-4dzw8 0/1 ContainerCreating 0 2s app=kubia kubia-mgz64 1/1 Running 0 27m app=foo kubia-tg29c 1/1 Running 0 29m app=kubia kubia-vwnmf 1/1 Running 0 25m app=kubia

可以发现初始创建的是三个Pod标签都是app=kubia,当把kubia-mgz64的标签设置为foo之后就脱离了当前ReplicationController的控制,这样ReplicationController控制的副本就变成了2个,所以会里面重新创建一个Pod;脱离控制的Pod还是照常运行,除非我们手动删除;

[d:\k8s]$ kubectl delete pod kubia-mgz64 pod "kubia-mgz64" deleted [d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-4dzw8 1/1 Running 0 20h app=kubia kubia-tg29c 1/1 Running 0 21h app=kubia kubia-vwnmf 1/1 Running 0 21h app=kubia

3.修改Pod模版

ReplicationController的pod模板可以随时修改:

[d:\k8s]$ kubectl edit rc kubia ...... replicationcontroller/kubia edited

使用如上命令即可,会弹出文本编辑器,修改Pod模版标签,如下所示:

template: metadata: creationTimestamp: null labels: app: kubia type: special

添加新的标签type:special,保存退出即可;修改Pod模版之后并不影响现有的pod,只会影响重新创建的pod:

[d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-4dzw8 1/1 Running 0 21h app=kubia kubia-tg29c 1/1 Running 0 21h app=kubia kubia-vwnmf 1/1 Running 0 21h app=kubia [d:\k8s]$ kubectl delete pod kubia-4dzw8 pod "kubia-4dzw8" deleted [d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-6qrxj 1/1 Running 0 2m12s app=kubia,type=special kubia-tg29c 1/1 Running 0 21h app=kubia kubia-vwnmf 1/1 Running 0 21h app=kubia

删除一个pod,重新创建的pod有了新的标签;

4.水平缩放pod

通过文本编辑器来修改副本数,修改spec.replicas为5

[d:\k8s]$ kubectl edit rc kubia replicationcontroller/kubia edited [d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-6qrxj 1/1 Running 0 9m49s app=kubia,type=special kubia-9crmf 0/1 ContainerCreating 0 4s app=kubia,type=special kubia-qpwbl 0/1 ContainerCreating 0 4s app=kubia,type=special kubia-tg29c 1/1 Running 0 21h app=kubia kubia-vwnmf 1/1 Running 0 21h app=kubia

可以发现自动创建了2个Pod,达到副本数5;通过kubectl scale重新修改为3:

[d:\k8s]$ kubectl scale rc kubia --replicas=3 replicationcontroller/kubia scaled [d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-6qrxj 1/1 Running 0 15m app=kubia,type=special kubia-tg29c 1/1 Running 0 22h app=kubia kubia-vwnmf 1/1 Running 0 21h app=kubia

5.删除ReplicationController

通过kubectl delete删除ReplicationController时默认会删除pod,但是也可以指定不删除:

[d:\k8s]$ kubectl delete rc kubia --cascade=false replicationcontroller "kubia" deleted [d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-6qrxj 1/1 Running 0 103m app=kubia,type=special kubia-tg29c 1/1 Running 0 23h app=kubia kubia-vwnmf 1/1 Running 0 23h app=kubia [d:\k8s]$ kubectl get rc kubia Error from server (NotFound): replicationcontrollers "kubia" not found

--cascade=false可以不删除pod,只删除ReplicationController

ReplicaSet

ReplicaSet是新一代ReplicationController,将完全替代ReplicationController;ReplicaSet的行为与ReplicationController完全相同,但pod选择器的表达能力更强;

1.创建ReplicaSet

apiVersion: apps/v1 kind: ReplicaSet metadata: name: kubia spec: replicas: 3 selector: matchLabels: app: kubia template: metadata: labels: app: kubia spec: containers: - name: kubia image: ksfzhaohui/kubia

apiVersion指定为apps/v1:apps表示API组,v1表示实际的API版本;如果是在核心的API组中,API是可以不用指定的,比如之前的ReplicationController只需要指定v1;
其他定义基本和ReplicationController类似,除了在selector下使用了matchLabels选择器;

[d:\k8s]$ kubectl create -f kubia-replicaset.yaml replicaset.apps/kubia created [d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS kubia-6qrxj 1/1 Running 0 150m app=kubia,type=special kubia-tg29c 1/1 Running 0 24h app=kubia kubia-vwnmf 1/1 Running 0 24h app=kubia [d:\k8s]$ kubectl get rs NAME DESIRED CURRENT READY AGE kubia 3 3 3 49s

创建完ReplicaSet之后,重新接管了原来的3个pod;更详细的可以使用describe命令:

[d:\k8s]$ kubectl describe rs Name: kubia Namespace: default Selector: app=kubia Labels: <none> Annotations: <none> Replicas: 3 current / 3 desired Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed Pod Template: Labels: app=kubia Containers: kubia: Image: ksfzhaohui/kubia Port: <none> Host Port: <none> Environment: <none> Mounts: <none> Volumes: <none> Events: <none>

可以看到Events事件列表为空,当前的3个pod都是接管的原来已经创建的pod;

2.ReplicaSet标签选择器

ReplicaSet相对于ReplicationController的主要改进是它更具表达力的标签选择器;

selector: matchExpressions: - key: app operator: In values: - kubia

ReplicaSet除了可以使用matchLabels,还可以使用功能更强大的matchExpressions;每个表达式都必须包含一个key、一个operator(运算符)、可能还有一个values的列表,运算符可以有:

3.删除ReplicaSet

[d:\k8s]$ kubectl delete rs kubia replicaset.apps "kubia" deleted [d:\k8s]$ kubectl get pods --show-labels No resources found in default namespace.

删除ReplicaSet的同时会删除其管理的pod;

DaemonSet

Replicationcontroller和ReplicaSet都用于在kubernetes集群上运行部署特定数量的pod;而DaemonSet可以在所有集群节点上运行一个pod,比如希望在每个节点上运行日志收集器和资源监控器;当然也可以通过节点选择器控制只有哪些节点运行pod;

1.创建DaemonSet

apiVersion: apps/v1 kind: DaemonSet metadata: name: ssd-monitor spec: selector: matchLabels: app: ssd-monitor template: metadata: labels: app: ssd-monitor spec: nodeSelector: disk: ssd containers: - name: main image: ksfzhaohui/kubia

准备如上创建DaemonSet的YAML文件,以上属性基本和ReplicaSet类似,除了nodeSelector也就是节点选择器,指定了选择disk=ssd标签;
的节点标签;

[d:\k8s]$ kubectl create -f ssd-monitor-daemonset.yaml daemonset.apps/ssd-monitor created [d:\k8s]$ kubectl get ds NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE ssd-monitor 0 0 0 0 0 disk=ssd 24s [d:\k8s]$ kubectl get pods --show-labels No resources found in default namespace.

创建完之后,并没有给当前节点创建pod,因为当前节点没有指定disk=ssd标签;

[d:\k8s]$ kubectl get node NAME STATUS ROLES AGE VERSION minikube Ready master 8d v1.17.0 [d:\k8s]$ kubectl label node minikube disk=ssd node/minikube labeled [d:\k8s]$ kubectl get node --show-labels NAME STATUS ROLES AGE VERSION LABELS minikube Ready master 8d v1.17.0 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,disk=ssd,gpu=true,kubernetes.io/arch=amd64,kubernetes.io/hostname=minikube,kubernetes.io/os=linux,node-role.kubernetes.io/master= [d:\k8s]$ kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS ssd-monitor-84hxd 1/1 Running 0 31s app=ssd-monitor,controller-revision-hash=5dc77f567d,pod-template-generation=1

首先获取当前节点名称为minikube,然后设置标签disk=ssd,这时候会自动在当前节点创建一个pod,因为在minikube中只有一个节点不好在多个节点上模拟;

2.删除pod和DaemonSet

[d:\k8s]$ kubectl label node minikube disk=hdd --overwrite node/minikube labeled [d:\k8s]$ kubectl get pods --show-labels No resources found in default namespace.

修改节点minkube的标签,可以发现节点上的pod会自动删除,因为不满足节点选择器;

[d:\k8s]$ kubectl delete ds ssd-monitor daemonset.apps "ssd-monitor" deleted [d:\k8s]$ kubectl get ds No resources found in default namespace.

删除DaemonSet也会一起删除这些pod;

Job

ReplicationController、ReplicaSet和DaemonSet会持续运行任务,永远达不到完成态,这些pod中的进程在退出时会重新启动;kubernetes通过Job资源允许你运行一种pod, 该pod在内部进程成功结束时,不重启容器,一旦任务完成,pod就被认为处千完成状态;
在发生节点故障时,该节点上由Job管理的pod,重新安排到其他节点;如果进程本身异常退出,可以将Job配置为重新启动容器;

1.创建Job

在创建Job前先准备一个构建在busybox的镜像,该容器将调用sleep 命令两分钟:

FROM busybox ENTRYPOINT echo "$(date) Batch job starting"; sleep 120; echo "$(date) Finished succesfully"

此镜像已经推送到docker hub:

kubernetes基本功能(Kubernetes副本机制篇)(3)

apiVersion: batch/v1 kind: Job metadata: name: batch-job spec: template: metadata: labels: app: batch-job spec: restartPolicy: OnFailure containers: - name: main image: ksfzhaohui/batch-job

Job属于batch API组,其中重要的属性是restartPolicy默认为Always表示无限期运行,其他选项还有OnFailure或Never,表示进程失败重启和不重启;

[d:\k8s]$ kubectl create -f exporter.yaml job.batch/batch-job created [d:\k8s]$ kubectl get job NAME COMPLETIONS DURATION AGE batch-job 0/1 7s 8s [d:\k8s]$ kubectl get pod NAME READY STATUS RESTARTS AGE batch-job-7sw68 1/1 Running 0 25s

创建Job,会自动创建一个pod,pod中的进程运行2分钟后会结束:

[d:\k8s]$ kubectl get pod NAME READY STATUS RESTARTS AGE batch-job-7sw68 0/1 Completed 0 3m1s [d:\k8s]$ kubectl get job NAME COMPLETIONS DURATION AGE batch-job 1/1 2m11s 3m12s

可以发现pod状态为Completed,同样job的COMPLETIONS同样为完成;

2.Job中运行多个pod实例

作业可以配置为创建多个pod实例,并以并行或串行方式运行它们;可以通过设置completions和parallelism属性来完成;

2.1 顺序运行Job pod

apiVersion: batch/v1 kind: Job metadata: name: multi-completion-batch-job spec: completions: 3 template: metadata: labels: app: multi-completion-batch-job spec: restartPolicy: OnFailure containers: - name: main image: ksfzhaohui/batch-job

completions设置为3,一个一个的运行3个pod,所有完成整个job完成;

[d:\k8s]$ kubectl get pod NAME READY STATUS RESTARTS AGE multi-completion-batch-job-h75j8 0/1 Completed 0 2m19s multi-completion-batch-job-wdhnj 1/1 Running 0 15s [d:\k8s]$ kubectl get job NAME COMPLETIONS DURATION AGE multi-completion-batch-job 1/3 2m28s 2m28s

可以看到完成一个pod之后会启动第二pod,所有都运行完之后如下所示:

[d:\k8s]$ kubectl get pod NAME READY STATUS RESTARTS AGE multi-completion-batch-job-4vjff 0/1 Completed 0 2m7s multi-completion-batch-job-h75j8 0/1 Completed 0 6m16s multi-completion-batch-job-wdhnj 0/1 Completed 0 4m12s [d:\k8s]$ kubectl get job NAME COMPLETIONS DURATION AGE multi-completion-batch-job 3/3 6m13s 6m18s

2.2 并行运行Job pod

apiVersion: batch/v1 kind: Job metadata: name: multi-completion-parallel-batch-job spec: completions: 3 parallelism: 2 template: metadata: labels: app: multi-completion-parallel-batch-job spec: restartPolicy: OnFailure containers: - name: main image: ksfzhaohui/batch-job

同时设置了completions和parallelism,表示job可以同时运行两个pod,其中任何一个执行完成可以运行第三个pod:

[d:\k8s]$ kubectl create -f multi-completion-parallel-batch-job.yaml job.batch/multi-completion-parallel-batch-job created [d:\k8s]$ kubectl get pod NAME READY STATUS RESTARTS AGE multi-completion-parallel-batch-job-f7wn8 0/1 ContainerCreating 0 3s multi-completion-parallel-batch-job-h9s29 0/1 ContainerCreating 0 3s

2.3 限制Job pod完成任务的时间

在pod配置中设置activeDeadlineSeconds属性,可以限制pod的时间;如果pod运行时间超过此时间,系统将尝试终止pod, 并将Job标记为失败;

apiVersion: batch/v1 kind: Job metadata: name: time-limited-batch-job spec: activeDeadlineSeconds: 30 template: metadata: labels: app: time-limited-batch-job spec: restartPolicy: OnFailure containers: - name: main image: ksfzhaohui/batch-job

指定activeDeadlineSeconds为30秒,超过30秒自动失败;

[d:\k8s]$ kubectl create -f time-limited-batch-job.yaml job.batch/time-limited-batch-job created [d:\k8s]$ kubectl get job NAME COMPLETIONS DURATION AGE time-limited-batch-job 0/1 3s 3s [d:\k8s]$ kubectl get pod NAME READY STATUS RESTARTS AGE time-limited-batch-job-jgmm6 1/1 Running 0 29s [d:\k8s]$ kubectl get pod NAME READY STATUS RESTARTS AGE time-limited-batch-job-jgmm6 1/1 Terminating 0 30s [d:\k8s]$ kubectl get pod No resources found in default namespace. [d:\k8s]$ kubectl get job NAME COMPLETIONS DURATION AGE time-limited-batch-job 0/1 101s 101s

可以观察AGE标签下面的时间表示已经运行的时间,30秒之后pod状态变成Terminating;

2.4 Job定期运行

job也支持定期执行,有点像quartz,也支持类似的quartz表达式:

apiVersion: batch/v1beta1 kind: CronJob metadata: name: corn-batch-job spec: schedule: "0-59 * * * *" jobTemplate: spec: template: metadata: labels: app: corn-batch-job spec: restartPolicy: OnFailure containers: - name: main image: ksfzhaohui/batch-job

指定schedule用来表示表达式分别是:分钟,小时,每个月中的第几天,月,星期几;以上配置表示每分钟运行一个job;

[d:\k8s]$ kubectl create -f cronjob.yaml cronjob.batch/corn-batch-job created [d:\k8s]$ kubectl get pod NAME READY STATUS RESTARTS AGE corn-batch-job-1577263560-w2fq2 0/1 Completed 0 3m3s corn-batch-job-1577263620-92pc7 1/1 Running 0 2m2s corn-batch-job-1577263680-tmr8p 1/1 Running 0 62s corn-batch-job-1577263740-jmzqk 0/1 ContainerCreating 0 2s [d:\k8s]$ kubectl get job NAME COMPLETIONS DURATION AGE corn-batch-job-1577263560 1/1 2m5s 3m48s corn-batch-job-1577263620 1/1 2m4s 2m47s corn-batch-job-1577263680 0/1 107s 107s corn-batch-job-1577263740 0/1 47s 47s

每个一分钟就运行一个job,可以删除CronJob

[d:\k8s]$ kubectl delete CronJob corn-batch-job cronjob.batch "corn-batch-job" deleted

总结

本文继续在阅读Kubernetes in Action过程中,实际操作的笔记;主要介绍了相关的副本机制探针,ReplicationController,ReplicaSet,DaemonSet以及Job相关知识点。

参考

Kubernetes in Action

博客地址

https://github.com/ksfzhaohui/blog

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