k8s通信方式(k8s控制器类型及演示)

一、Pod控制器

Pod 的分类

1.自主式 Pod

Pod 退出后不会被创建

2.控制器管理的 Pod

在控制器的生命周期里,始终要维持 Pod 的副本数目

3.控制器类型

Replication Controller和ReplicaSet Deployment DaemonSet StatefulSet Job CronJob HPA全称Horizontal Pod Autoscaler Replication Controller和ReplicaSet ReplicaSet (RS)是下一代的 Replication Controller(RC),官方推荐使用ReplicaSet。

ReplicaSet 和 Replication Controller 的唯一区别是选择器的支持,ReplicaSet 支持新的基于集合的选择器需求。

ReplicaSet 确保任何时间都有指定数量的 Pod 副本在运行。

虽然 ReplicaSets 可以独立使用,但今天它主要被Deployments 用作协调 Pod 创建、删除和更新的机制。

k8s通信方式(k8s控制器类型及演示)(1)

1>Deployment

Deployment 为 Pod 和 ReplicaSet 提供了一个申明式的定义方法。

.典型的应用场景:

用来创建Pod和ReplicaSet 滚动更新和回滚 扩容和缩容 暂停与恢复

2>DaemonSet

DaemonSet 确保全部(或者某些)节点上运行一个 Pod 的副本。当有节点加入集群时, 也会为他们新增一个 Pod 。当有节点从集群移除时,这些 Pod 也会被回收。删除 DaemonSet 将会删除它创建的所有 Pod。

DaemonSet 的典型用法:

在每个节点上运行集群存储 DaemonSet,例如 glusterd、ceph。 在每个节点上运行日志收集 DaemonSet,例如 fluentd、logstash。 在每个节点上运行监控 DaemonSet,例如 Prometheus Node Exporter、zabbix agent等 一个简单的用法是在所有的节点上都启动一个 DaemonSet,将被作为每种类型的 daemon 使用。

一个稍微复杂的用法是单独对每种 daemon 类型使用多个 DaemonSet,但具有不同的标志, 并且对不同硬件类型具有不同的内存、CPU 要求。

3>StatefulSet

StatefulSet 是用来管理有状态应用的工作负载 API 对象。实例之间有不对等关系,以及实例对外部数据有依赖关系的应用,称为“有状态应用”

StatefulSet 用来管理 Deployment 和扩展一组 Pod,并且能为这些 Pod 提供序号和唯一性保证。

StatefulSets 对于需要满足以下一个或多个需求的应用程序很有价值:

稳定的、唯一的网络标识符。 稳定的、持久的存储。 有序的、优雅的部署和缩放。 有序的、自动的滚动更新。 Job 执行批处理任务,仅执行一次任务,保证任务的一个或多个Pod成功结束。

4>CronJob

Cron Job 创建基于时间调度的 Jobs。

一个 CronJob 对象就像 crontab (cron table) 文件中的一行,它用 Cron 格式进行编写,并周期性地在给定的调度时间执行 Job。

HPA 根据资源利用率自动调整service中Pod数量,实现Pod水平自动缩放。

k8s通信方式(k8s控制器类型及演示)(2)

二、Pod控制器使用示例

ReplicaSet举例

1.编辑以下yaml文件:

[root@server1 ~]# vim rs.yaml [root@server1 ~]# cat rs.yaml apiVersion: apps/v1 kind: ReplicaSet metadata: name: replicaset-example spec: replicas: 2 #启动pod的副本数 selector: #定义选择器为标签选择器。 matchLabels: app: nginx template: metadata: labels: app: nginx #定义容器的标签 spec: #定义容器 containers: - name: nginx image: nginx

2.运行

以上使用的控制器的RS,RS控制器通过pod的标签(matchLabels)来控制pod的数量,使用apply命令可以实现创建,更新pod,而create命令创建后若需要更新只能删除之后再创建,因此建议使用apply:

[root@server1 ~]# kubectl apply -f rs.yaml replicaset.apps/replicaset-example created [root@server1 ~]# kubectl apply -f rs.yaml replicaset.apps/replicaset-example unchanged

3.查看状态:

查看状态:

[root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE replicaset-example-p6sv6 1/1 Running 0 34s replicaset-example-s5jps 1/1 Running 0 34s [root@server1 ~]# kubectl get rs #获取rs的信息 NAME DESIRED CURRENT READY AGE replicaset-example 2 2 2 36s [root@server1 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES replicaset-example-p6sv6 1/1 Running 0 38s 10.244.1.14 server2 <none> <none> replicaset-example-s5jps 1/1 Running 0 38s 10.244.2.21 server3 <none> <none>

可以看出一切正常,接下来进行pod的拉伸与压缩:

4.拉伸副本数:

[root@server1 ~]# vim rs.yaml [root@server1 ~]# cat rs.yaml apiVersion: apps/v1 kind: ReplicaSet metadata: name: replicaset-example spec: replicas: 4 #拉伸为4个 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx [root@server1 ~]# kubectl apply -f rs.yaml replicaset.apps/replicaset-example configured

5.查看pod数:

[root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE replicaset-example-p6sv6 1/1 Running 0 97s replicaset-example-s5jps 1/1 Running 0 97s replicaset-example-wzclz 1/1 Running 0 21s replicaset-example-zk4mb 1/1 Running 0 21s

已经被拉伸成了4个。

6.缩减:

[root@server1 ~]# vim rs.yaml [root@server1 ~]# cat rs.yaml apiVersion: apps/v1 kind: ReplicaSet metadata: name: replicaset-example spec: replicas: 2 #缩减为2个 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx [root@server1 ~]# kubectl apply -f rs.yaml replicaset.apps/replicaset-example configured [root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE replicaset-example-p6sv6 1/1 Running 0 2m6s replicaset-example-s5jps 1/1 Running 0 2m6s

可以看出删除的是刚刚创建的那两个pod。

7.更改一个pod 的标签:

[root@server1 ~]# kubectl label pod replicaset-example-s5jps app=myapp --overwrite #将标签强制更改为myapp pod/replicaset-example-s5jps labeled [root@server1 ~]# kubectl get pod --show-labels NAME READY STATUS RESTARTS AGE LABELS replicaset-example-p6sv6 1/1 Running 0 3m56s app=nginx replicaset-example-s5jps 1/1 Running 0 3m56s app=myapp replicaset-example-w98nk 1/1 Running 0 26s app=nginx

可以看出现在有3个pod,两个标签为nginx一个为myapp,RS控制器的工作原理就是维持标签为nginx的pod个数有2个,因此当我们更改一个pod的标签后,RS又会给我们创建一个标签为nginx的pod,而当我们将标签为myapp的pod删除后RS控制器不会有操作:

[root@server1 ~]# kubectl delete pod replicaset-example-s5jps pod "replicaset-example-s5jps" deleted [root@server1 ~]# kubectl get pod --show-labels NAME READY STATUS RESTARTS AGE LABELS replicaset-example-p6sv6 1/1 Running 0 5m8s app=nginx replicaset-example-w98nk 1/1 Running 0 98s app=nginx

8.再更改验证:

[root@server1 ~]# kubectl label pod replicaset-example-p6sv6 app=myapp --overwrite #首先保证3个pod pod/replicaset-example-p6sv6 labeled [root@server1 ~]# kubectl get pod --show-labels NAME READY STATUS RESTARTS AGE LABELS replicaset-example-p6sv6 1/1 Running 0 6m4s app=myapp replicaset-example-w98nk 1/1 Running 0 2m34s app=nginx replicaset-example-x2lq9 1/1 Running 0 26s app=nginx [root@server1 ~]# kubectl label pod replicaset-example-p6sv6 app=nginx --overwrite pod/replicaset-example-p6sv6 labeled [root@server1 ~]# kubectl get pod --show-labels NAME READY STATUS RESTARTS AGE LABELS replicaset-example-p6sv6 1/1 Running 0 6m23s app=nginx replicaset-example-w98nk 1/1 Running 0 2m53s app=nginx replicaset-example-x2lq9 0/1 Terminating 0 45s app=nginx [root@server1 ~]# kubectl get pod --show-labels NAME READY STATUS RESTARTS AGE LABELS replicaset-example-p6sv6 1/1 Running 0 6m25s app=nginx replicaset-example-w98nk 1/1 Running 0 2m55s app=nginx

以上实验可以看出,当集群里有3个标签是nginx的pod的时候,RS控制器又会帮我们将最后创建的pod删除。

实验后删除:

[root@server1 ~]# kubectl delete -f rs.yaml replicaset.apps "replicaset-example" deleted

Deployment控制器示例

1.编辑yaml文件:

Deployment控制器示例 编辑yaml文件:

[root@server1 ~]# vim deployment.yaml [root@server1 ~]# cat deployment.yaml apiVersion: apps/v1 kind: Deployment metadata: name: deployment-nginx labels: app: nginx spec: replicas: 2 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: ikubernetes/myapp:v1 ports: - containerPort: 80

2.创建pod:

[root@server1 ~]# kubectl apply -f deployment.yaml deployment.apps/deployment-nginx created [root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE deployment-nginx-56d786cd98-kx5pw 1/1 Running 0 23s deployment-nginx-56d786cd98-qgcjl 1/1 Running 0 23s [root@server1 ~]# kubectl get rs NAME DESIRED CURRENT READY AGE deployment-nginx-56d786cd98 2 2 2 28s [root@server1 ~]# kubectl get deployments.apps #查看deployments NAME READY UP-TO-DATE AVAILABLE AGE deployment-nginx 2/2 2 2 32s

以上运行结果可以看出deployments底层也是由RS实现的,接下来

3.进行拉伸:

[root@server1 ~]# vim deployment.yaml [root@server1 ~]# cat deployment.yaml apiVersion: apps/v1 kind: Deployment metadata: name: deployment-nginx labels: app: nginx spec: replicas: 4 #拉伸为4个 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: ikubernetes/myapp:v1 ports: - containerPort: 80 [root@server1 ~]# kubectl apply -f deployment.yaml deployment.apps/deployment-nginx configured [root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE deployment-nginx-56d786cd98-942dh 1/1 Running 0 26s deployment-nginx-56d786cd98-kx5pw 1/1 Running 0 108s deployment-nginx-56d786cd98-qgcjl 1/1 Running 0 108s deployment-nginx-56d786cd98-zb8s8 1/1 Running 0 26s

可以看出已经拉伸为4个。接下来进行

4.滚动更新:

[root@server1 ~]# vim deployment.yaml [root@server1 ~]# cat deployment.yaml apiVersion: apps/v1 kind: Deployment metadata: name: deployment-nginx labels: app: nginx spec: replicas: 4 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: ikubernetes/myapp:v2 #更新到v2 ports: - containerPort: 80 [root@server1 ~]# kubectl apply -f deployment.yaml deployment.apps/deployment-nginx configured [root@server1 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES deployment-nginx-868855d887-2zh45 1/1 Running 0 2m39s 10.244.2.26 server3 <none> <none> deployment-nginx-868855d887-87m22 1/1 Running 0 2m34s 10.244.1.20 server2 <none> <none> deployment-nginx-868855d887-hb6mv 1/1 Running 0 2m39s 10.244.1.19 server2 <none> <none> deployment-nginx-868855d887-v8ndt 1/1 Running 0 2m33s 10.244.2.27 server3 <none> <none> [root@server1 ~]# curl 10.244.2.26 Hello MyApp | Version: v2 | Pod Name

可以看出更新时控制器新建一个rs,然后再新建4个pod,原来的rs依然存在,为了方便我们

5.进行回滚:

[root@server1 ~]# vim deployment.yaml [root@server1 ~]# cat deployment.yaml apiVersion: apps/v1 kind: Deployment metadata: name: deployment-nginx labels: app: nginx spec: replicas: 4 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: ikubernetes/myapp:v1 ports: - containerPort: 80 [root@server1 ~]# kubectl apply -f deployment.yaml deployment.apps/deployment-nginx configured [root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE deployment-nginx-56d786cd98-78m7z 0/1 ContainerCreating 0 4s deployment-nginx-56d786cd98-8hnns 1/1 Running 0 9s deployment-nginx-56d786cd98-lcvzw 1/1 Running 0 9s deployment-nginx-56d786cd98-xkjhq 0/1 ContainerCreating 0 3s deployment-nginx-868855d887-2zh45 1/1 Running 0 3m22s deployment-nginx-868855d887-hb6mv 1/1 Terminating 0 3m22s deployment-nginx-868855d887-v8ndt 1/1 Terminating 0 3m16s [root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE deployment-nginx-56d786cd98-78m7z 1/1 Running 0 26s deployment-nginx-56d786cd98-8hnns 1/1 Running 0 31s deployment-nginx-56d786cd98-lcvzw 1/1 Running 0 31s deployment-nginx-56d786cd98-xkjhq 1/1 Running 0 25s

可以看出原来v1版本的rs被重新启用,在原来的rs下面新建4个pod。当然我们也可以使用kubectl delete rs --all命令删除不用的rs(注意:正在使用的rs不会删除):

[root@server1 ~]# kubectl delete rs --all replicaset.apps "deployment-nginx-56d786cd98" deleted replicaset.apps "deployment-nginx-868855d887" deleted [root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE deployment-nginx-56d786cd98-6r589 1/1 Running 0 21s deployment-nginx-56d786cd98-hvz24 1/1 Running 0 21s deployment-nginx-56d786cd98-k62lj 1/1 Running 0 21s deployment-nginx-56d786cd98-ss97z 1/1 Running 0 21s [root@server1 ~]# kubectl get rs NAME DESIRED CURRENT READY AGE deployment-nginx-56d786cd98 4 4 4 24s #正在使用的RS不会删除

实验后删除:

[root@server1 ~]# kubectl delete -f deployment.yaml deployment.apps "deployment-nginx" deleted

k8s通信方式(k8s控制器类型及演示)(3)

DaemonSet举例

1.编辑yaml

DaemonSet控制器保证每个节点上都运行一个pod:

[root@server1 ~]# vim daemonset.yaml [root@server1 ~]# cat daemonset.yaml apiVersion: apps/v1 kind: DaemonSet metadata: name: daemonset-example labels: app: zabbix-agent spec: selector: matchLabels: name: zabbix-agent template: metadata: labels: name: zabbix-agent spec: containers: - name: zabbix-agent image: zabbix/zabbix-agent

2.创建pod:

[root@server1 ~]# kubectl apply -f daemonset.yaml daemonset.apps/daemonset-example created [root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE daemonset-example-ctbgh 1/1 Running 0 6m5s daemonset-example-mdqzk 1/1 Running 0 6m5s [root@server1 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES daemonset-example-ctbgh 1/1 Running 0 7m16s 10.244.2.32 server3 <none> <none> daemonset-example-mdqzk 1/1 Running 0 7m16s 10.244.1.25 server2 <none> <none>

可以看出我们的每个节点(server3和server2)上都运行了一个pod

3.删除一个pod:

[root@server1 ~]# kubectl delete pod daemonset-example-ctbgh pod "daemonset-example-ctbgh" deleted [root@server1 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES daemonset-example-998ck 0/1 ContainerCreating 0 8s <none> server3 <none> <none> daemonset-example-mdqzk 1/1 Running 0 8m22s 10.244.1.25 server2 <none> <none> [root@server1 ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES daemonset-example-998ck 1/1 Running 0 24s 10.244.2.33 server3 <none> <none> daemonset-example-mdqzk 1/1 Running 0 8m38s 10.244.1.25 server2 <none> <none>

可以看出删除后DaemonSet控制器又会帮我们创建pod,以保证每个节点运行一个pod。

实验后删除:

[root@server1 ~]# kubectl delete -f daemonset.yaml daemonset.apps "daemonset-example" deleted

Job控制器举例

1.编辑yaml

Job控制器只运行一次

[root@server1 ~]# vim job.yaml [root@server1 ~]# cat job.yaml apiVersion: batch/v1 kind: Job metadata: name: pi spec: template: spec: containers: - name: pi image: perl #利用perl计算圆周率 command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"] restartPolicy: Never backoffLimit: 4 #容器启动失败重启4次之后不再重启。

2.创建

kubectl apply -f job.yaml

由于Job只运行一次,因此运行完后状态为Completed,我们可以查看日志获取结果:

可以看出计算成功。

实验后删除:

[root@server1 ~]# kubectl delete -f job.yaml job.batch "pi" deleted CronJob控制器举例 CronJob控制器用于定时执行任务: [root@server1 ~]# vim cronjob.yaml [root@server1 ~]# cat cronjob.yaml apiVersion: batch/v1beta1 kind: CronJob metadata: name: cronjob-example spec: schedule: "* * * * " jobTemplate: spec: template: spec: containers: - name: cronjob image: busybox args: - /bin/sh - -c - date; echo Hello from k8s cluster #输出信息 restartPolicy: OnFailure

Crontab

其中schedule字段与crontab里面的写法相同," * * "表示每分钟执行任务。

1.创建pod:

[root@server1 ~]# kubectl apply -f cronjob.yaml cronjob.batch/cronjob-example created root@server1 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE cronjob-example-1587387120-ngt6n 0/1 ContainerCreating 0 16s [root@server1 ~]# kubectl get pod #等待一分钟 NAME READY STATUS RESTARTS AGE cronjob-example-1587387120-ngt6n 0/1 Completed 0 60s cronjob-example-1587387180-hbwzb 0/1 ContainerCreating 0 9s

可以看出每分钟运行一个pod,查看日志获取输出信息:

[root@server1 ~]# kubectl logs cronjob-example-1587387120-ngt6n Mon Apr 20 12:52:30 UTC 2020 Hello from k8s cluster [root@server1 ~]# kubectl logs cronjob-example-1587387180-hbwzb Mon Apr 20 12:53:35 UTC 2020 Hello from k8s cluster

可以看出输出也是每分钟输出一次,也可以使用以下命令查看cronjob的信息:

[root@server1 ~]# kubectl get cronjobs NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE cronjob-example * * * * * False 1 16s 3m10s [root@server1 ~]# kubectl get job -w #查看job信息并且持续输出 NAME COMPLETIONS DURATION AGE cronjob-example-1587387120 1/1 20s 2m23s cronjob-example-1587387180 1/1 35s 92s cronjob-example-1587387240 1/1 20s 32s

实验后删除

[root@server1 ~]# kubectl delete -f cronjob.yaml cronjob.batch "cronjob-example" deleted

,

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