大佬教程收集整理的这篇文章主要介绍了kubernetes系列教程(七)深入玩转pod调度,大佬教程大佬觉得挺不错的,现在分享给大家,也给大家做个参考。
上一篇文章中kubernetes系列教程(六)kubernetes资源管理和服务质量初步介绍了kubernetes中的resource资源调度和服务质量Qos,介绍了kubernetes中如何定义pod的资源和资源调度,以及设置resource之后的优先级别Qos,接下来介绍kubernetes系列教程pod的调度机制。
kubernets是容器编排引擎,其中最主要的一个功能是容器的调度,通过kube-scheduler实现容器的完全自动化调度,调度周期分为:调度周期scheduling Cycle和绑定周期Binding Cycle,其中调度周期细分为过滤filter和weight称重,按照指定的调度策略将满足运行pod节点的node赛选出来,然后进行排序;绑定周期是经过kube-scheduler调度优选的pod后,由特定的node节点watch然后通过kubelet运行。
过滤阶段包含预选PreDicate和scoring排序,预选是筛选满足条件的node,排序是最满足条件的node打分并排序,预选的算法包含有:
过滤条件需要检查node上满足的条件,可以通过kubectl describe node node-id方式查看,如下图:
优选调度算法有:
nodename是PodSpec中的一个字段,可以通过pod.spec.nodename指定将pod调度到某个具体的node节点上,该字段比较特殊一般都为空,如果有设置nodename字段,kube-scheduler会直接跳过调度,在特定节点上通过kubelet启动pod。通过nodename调度并非是集群的智能调度,通过指定调度的方式可能会存在资源不均匀的情况,建议设置Guaranteed的Qos,防止资源不均时候Pod被驱逐evince。如下以创建一个pod运行在Node-3上为例:
[root@node-1 demo]# cat Nginx-nodename.yaml
apiVersion: v1
kind: Pod
Metadata:
name: Nginx-run-on-nodename
Annotations:
kubernetes.io/description: "Running the Pod on specific nodename"
spec:
containers:
- name: Nginx-run-on-nodename
image: Nginx:latest
ports:
- name: http-80-port
protocol: TCP
containerPort: 80
nodename: node-3 #通过nodename指定将Nginx-run-on-nodename运行在特定节点node-3上
[root@node-1 demo]# kubectl apply -f Nginx-nodename.yaml
pod/Nginx-run-on-nodename created
[root@node-1 demo]# kubectl get pods Nginx-run-on-nodename -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READInesS GATES
Nginx-run-on-nodename 1/1 Running 0 6m52s 10.244.2.15 node-3 <none> <none>
nodeSELEctor是PodSpec中的一个字段,nodeSELEctor是最简单实现将pod运行在特定node节点的实现方式,其通过指定key和value键值对的方式实现,需要node设置上匹配的Labels,节点调度的时候指定上特定的labels即可。如下以node-2添加一个app:web的labels,调度pod的时候通过nodeSELEctor选择该labels:
[root@node-1 demo]# kubectl label node node-2 app=web
node/node-2 labeled
[root@node-1 demo]# kubectl get nodes --show-labels
NAME STATUS ROLES AGE VERSION LABELS
node-1 Ready master 15d v1.15.3 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node-1,kubernetes.io/os=linux,node-role.kubernetes.io/master=
node-2 Ready <none> 15d v1.15.3 app=web,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node-2,kubernetes.io/os=linux
node-3 Ready <none> 15d v1.15.3 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node-3,kubernetes.io/os=linux
[root@node-1 demo]# cat Nginx-nodeSELEctor.yaml
apiVersion: v1
kind: Pod
Metadata:
name: Nginx-run-on-nodeSELEctor
Annotations:
kubernetes.io/description: "Running the Pod on specific node by nodeSELEctor"
spec:
containers:
- name: Nginx-run-on-nodeSELEctor
image: Nginx:latest
ports:
- name: http-80-port
protocol: TCP
containerPort: 80
nodeSELEctor: #通过nodeSELEctor将pod调度到特定的labels
app: web
[root@node-1 demo]# kubectl apply -f Nginx-nodeSELEctor.yaml
pod/Nginx-run-on-nodeSELEctor created
[root@node-1 demo]# kubectl get pods Nginx-run-on-nodeSELEctor -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READInesS GATES
Nginx-run-on-nodeSELEctor 1/1 Running 0 51s 10.244.1.24 node-2 <none> <none>
系统默认预先定义有多种内置的labels,这些labels可以标识node的属性,如arch架构,操作系统类型,主机名等
affinity/anti-affinity和nodeSELEctor功能相类似,相比于nodeSELEctor,affinity的功能更加丰富,未来会取代nodeSELEctor,affinity增加了如下的一些功能增强:
下面通过一个例子来演示node affinity的使用,requiredDuringschedulingIgnoredDuringExecution指定需要满足的条件,preferredDuringschedulingIgnoredDuringExecution指定优选的条件,两者之间取与关系。
[root@node-1 ~]# kubectl get nodes --show-labels
NAME STATUS ROLES AGE VERSION LABELS
node-1 Ready master 15d v1.15.3 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node-1,kubernetes.io/os=linux,node-role.kubernetes.io/master=
node-2 Ready <none> 15d v1.15.3 app=web,beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node-2,kubernetes.io/os=linux
node-3 Ready <none> 15d v1.15.3 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=node-3,kubernetes.io/os=linux
[root@node-1 demo]# cat Nginx-node-affinity.yaml
apiVersion: v1
kind: Pod
Metadata:
name: Nginx-run-node-affinity
Annotations:
kubernetes.io/description: "Running the Pod on specific node by node affinity"
spec:
containers:
- name: Nginx-run-node-affinity
image: Nginx:latest
ports:
- name: http-80-port
protocol: TCP
containerPort: 80
affinity:
nodeAffinity:
requiredDuringschedulingIgnoredDuringExecution:
nodeSELEctorTerms:
- matchExpressions:
- key: kubernetes.io/hostname
operator: In
values:
- node-1
- node-2
- node-3
preferredDuringschedulingIgnoredDuringExecution:
- weight: 1
preference:
matchExpressions:
- key: app
operator: In
values: ["web"]
[root@node-1 demo]# kubectl apply -f Nginx-node-affinity.yaml
pod/Nginx-run-node-affinity created
[root@node-1 demo]# kubectl get pods --show-labels Nginx-run-node-affinity -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READInesS GATES LABELS
Nginx-run-node-affinity 1/1 Running 0 106s 10.244.1.25 node-2 <none> <none> <none>
本文介绍了kubernetes中的调度机制,默认创建pod是全自动调度机制,调度由kube-scheduler实现,调度过程分为两个阶段调度阶段(过滤和沉重排序)和绑定阶段(在Node上运行pod)。通过干预有四种方式:
调度框架介绍:https://kubernetes.io/docs/concepts/configuration/scheduling-framework/
Pod调度方法:https://kubernetes.io/docs/concepts/configuration/assign-pod-node/
返回kubernetes系列教程目录
以上是大佬教程为你收集整理的kubernetes系列教程(七)深入玩转pod调度全部内容,希望文章能够帮你解决kubernetes系列教程(七)深入玩转pod调度所遇到的程序开发问题。
如果觉得大佬教程网站内容还不错,欢迎将大佬教程推荐给程序员好友。
本图文内容来源于网友网络收集整理提供,作为学习参考使用,版权属于原作者。
如您有任何意见或建议可联系处理。小编QQ:384754419,请注明来意。