Kubernetes K8S之固定节点nodeName和nodeSelector调度详解与示例

主机配置规划

服务器名称(hostname) 系统版本 配置 内网IP 外网IP(模拟)
k8s-master CentOS7.7 2C/4G/20G 172.16.1.110 10.0.0.110
k8s-node01 CentOS7.7 2C/4G/20G 172.16.1.111 10.0.0.111
k8s-node02 CentOS7.7 2C/4G/20G 172.16.1.112 10.0.0.112

nodeName调度

nodeName是节点选择约束的最简单形式，但是由于其限制，通常很少使用它。nodeName是PodSpec的领域。

pod.spec.nodeName将Pod直接调度到指定的Node节点上，会【跳过Scheduler的调度策略】，该匹配规则是【强制】匹配。可以越过Taints污点进行调度。

nodeName用于选择节点的一些限制是：

  • 如果指定的节点不存在，则容器将不会运行，并且在某些情况下可能会自动删除。
  • 如果指定的节点没有足够的资源来容纳该Pod，则该Pod将会失败，并且其原因将被指出，例如OutOfmemory或OutOfcpu。
  • 云环境中的节点名称并非总是可预测或稳定的。

nodeName示例

获取当前的节点信息

1 [root@k8s-master scheduler]# kubectl get nodes -o wide

2 NAME         STATUS   ROLES    AGE   VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION           CONTAINER-RUNTIME

3 k8s-master   Ready    master   42d   v1.17.4   172.16.1.110   <none>        CentOS Linux 7 (Core)   3.10.0-1062.el7.x86_64   docker://19.3.8

4 k8s-node01   Ready    <none>   42d   v1.17.4   172.16.1.111   <none>        CentOS Linux 7 (Core)   3.10.0-1062.el7.x86_64   docker://19.3.8

5 k8s-node02   Ready    <none>   42d   v1.17.4   172.16.1.112   <none>        CentOS Linux 7 (Core)   3.10.0-1062.el7.x86_64   docker://19.3.8

当nodeName指定节点存在

要运行的yaml文件

 1 [root@k8s-master scheduler]# pwd

 2 /root/k8s_practice/scheduler

 3 [root@k8s-master scheduler]# cat scheduler_nodeName.yaml

 4 apiVersion: apps/v1

 5 kind: Deployment

 6 metadata:

 7   name: scheduler-nodename-deploy

 8   labels:

 9     app: nodename-deploy

10 spec:

11   replicas: 5

12   selector:

13     matchLabels:

14       app: myapp

15   template:

16     metadata:

17       labels:

18         app: myapp

19     spec:

20       containers:

21       - name: myapp-pod

22         image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1

23         imagePullPolicy: IfNotPresent

24         ports:

25           - containerPort: 80

26       # 指定节点运行

27       nodeName: k8s-master

运行yaml文件并查看信息

 1 [root@k8s-master scheduler]# kubectl apply -f scheduler_nodeName.yaml

 2 deployment.apps/scheduler-nodename-deploy created

 3 [root@k8s-master scheduler]#

 4 [root@k8s-master scheduler]# kubectl get deploy -o wide

 5 NAME                        READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                      SELECTOR

 6 scheduler-nodename-deploy   0/5     5            0           6s    myapp-pod    registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp

 7 [root@k8s-master scheduler]#

 8 [root@k8s-master scheduler]# kubectl get rs -o wide

 9 NAME                                  DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES                                                      SELECTOR

10 scheduler-nodename-deploy-d5c9574bd   5         5         5       15s   myapp-pod    registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp,pod-template-hash=d5c9574bd

11 [root@k8s-master scheduler]#

12 [root@k8s-master scheduler]# kubectl get pod -o wide

13 NAME                                        READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES

14 scheduler-nodename-deploy-d5c9574bd-6l9d8   1/1     Running   0          23s   10.244.0.123   k8s-master   <none>           <none>

15 scheduler-nodename-deploy-d5c9574bd-c82cc   1/1     Running   0          23s   10.244.0.119   k8s-master   <none>           <none>

16 scheduler-nodename-deploy-d5c9574bd-dkkjg   1/1     Running   0          23s   10.244.0.122   k8s-master   <none>           <none>

17 scheduler-nodename-deploy-d5c9574bd-hcn77   1/1     Running   0          23s   10.244.0.121   k8s-master   <none>           <none>

18 scheduler-nodename-deploy-d5c9574bd-zstjx   1/1     Running   0          23s   10.244.0.120   k8s-master   <none>           <none>

由上可见，yaml文件中nodeName: k8s-master生效，所有pod被调度到了k8s-master节点。如果这里是nodeName: k8s-node02，那么就会直接调度到k8s-node02节点。

当nodeName指定节点不存在

要运行的yaml文件

 1 [root@k8s-master scheduler]# pwd

 2 /root/k8s_practice/scheduler

 3 [root@k8s-master scheduler]# cat scheduler_nodeName_02.yaml

 4 apiVersion: apps/v1

 5 kind: Deployment

 6 metadata:

 7   name: scheduler-nodename-deploy

 8   labels:

 9     app: nodename-deploy

10 spec:

11   replicas: 5

12   selector:

13     matchLabels:

14       app: myapp

15   template:

16     metadata:

17       labels:

18         app: myapp

19     spec:

20       containers:

21       - name: myapp-pod

22         image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1

23         imagePullPolicy: IfNotPresent

24         ports:

25           - containerPort: 80

26       # 指定节点运行，该节点不存在

27       nodeName: k8s-node08

运行yaml文件并查看信息

 1 [root@k8s-master scheduler]# kubectl apply -f scheduler_nodeName_02.yaml

 2 deployment.apps/scheduler-nodename-deploy created

 3 [root@k8s-master scheduler]#

 4 [root@k8s-master scheduler]# kubectl get deploy -o wide

 5 NAME                        READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                      SELECTOR

 6 scheduler-nodename-deploy   0/5     5            0           4s    myapp-pod    registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp

 7 [root@k8s-master scheduler]#

 8 [root@k8s-master scheduler]# kubectl get rs -o wide

 9 NAME                                   DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES                                                      SELECTOR

10 scheduler-nodename-deploy-75944bdc5d   5         5         0       9s    myapp-pod    registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp,pod-template-hash=75944bdc5d

11 [root@k8s-master scheduler]#

12 [root@k8s-master scheduler]# kubectl get pod -o wide

13 NAME                                         READY   STATUS    RESTARTS   AGE   IP       NODE         NOMINATED NODE   READINESS GATES

14 scheduler-nodename-deploy-75944bdc5d-c8f5d   0/1     Pending   0          13s   <none>   k8s-node08   <none>           <none>

15 scheduler-nodename-deploy-75944bdc5d-hfdlv   0/1     Pending   0          13s   <none>   k8s-node08   <none>           <none>

16 scheduler-nodename-deploy-75944bdc5d-q9qgt   0/1     Pending   0          13s   <none>   k8s-node08   <none>           <none>

17 scheduler-nodename-deploy-75944bdc5d-q9zl7   0/1     Pending   0          13s   <none>   k8s-node08   <none>           <none>

18 scheduler-nodename-deploy-75944bdc5d-wxsnv   0/1     Pending   0          13s   <none>   k8s-node08   <none>           <none>

由上可见，如果指定的节点不存在，则容器将不会运行，一直处于Pending 状态。

nodeSelector调度

nodeSelector是节点选择约束的最简单推荐形式。nodeSelector是PodSpec的领域。它指定键值对的映射。

Pod.spec.nodeSelector是通过Kubernetes的label-selector机制选择节点，由调度器调度策略匹配label，而后调度Pod到目标节点，该匹配规则属于【强制】约束。由于是调度器调度，因此不能越过Taints污点进行调度。

nodeSelector示例

获取当前的节点信息

1 [root@k8s-master ~]# kubectl get node -o wide --show-labels

2 NAME         STATUS   ROLES    AGE   VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION           CONTAINER-RUNTIME   LABELS

3 k8s-master   Ready    master   42d   v1.17.4   172.16.1.110   <none>        CentOS Linux 7 (Core)   3.10.0-1062.el7.x86_64   docker://19.3.8     beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master,kubernetes.io/os=linux,node-role.kubernetes.io/master=

4 k8s-node01   Ready    <none>   42d   v1.17.4   172.16.1.111   <none>        CentOS Linux 7 (Core)   3.10.0-1062.el7.x86_64   docker://19.3.8     beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node01,kubernetes.io/os=linux

5 k8s-node02   Ready    <none>   42d   v1.17.4   172.16.1.112   <none>        CentOS Linux 7 (Core)   3.10.0-1062.el7.x86_64   docker://19.3.8     beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node02,kubernetes.io/os=linux

添加label标签

运行kubectl get nodes以获取群集节点的名称。然后可以对指定节点添加标签。比如：k8s-node01的磁盘为SSD，那么添加disk-type=ssd；k8s-node02的CPU核数高，那么添加cpu-type=hight；如果为Web机器，那么添加service-type=web。怎么添加标签可以根据实际规划情况而定。

 1 ### 给k8s-node01 添加指定标签

 2 [root@k8s-master ~]# kubectl label nodes k8s-node01 disk-type=ssd

 3 node/k8s-node01 labeled

 4 #### 删除标签命令 kubectl label nodes k8s-node01 disk-type-

 5 [root@k8s-master ~]#

 6 [root@k8s-master ~]# kubectl get node --show-labels

 7 NAME         STATUS   ROLES    AGE   VERSION   LABELS

 8 k8s-master   Ready    master   42d   v1.17.4   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master,kubernetes.io/os=linux,node-role.kubernetes.io/master=

 9 k8s-node01   Ready    <none>   42d   v1.17.4   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,disk-type=ssd,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node01,kubernetes.io/os=linux

10 k8s-node02   Ready    <none>   42d   v1.17.4   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node02,kubernetes.io/os=linux

由上可见，已经为k8s-node01节点添加了disk-type=ssd 标签。

当nodeSelector标签存在

要运行的yaml文件

 1 [root@k8s-master scheduler]# pwd

 2 /root/k8s_practice/scheduler

 3 [root@k8s-master scheduler]#

 4 [root@k8s-master scheduler]# cat scheduler_nodeSelector.yaml

 5 apiVersion: apps/v1

 6 kind: Deployment

 7 metadata:

 8   name: scheduler-nodeselector-deploy

 9   labels:

10     app: nodeselector-deploy

11 spec:

12   replicas: 5

13   selector:

14     matchLabels:

15       app: myapp

16   template:

17     metadata:

18       labels:

19         app: myapp

20     spec:

21       containers:

22       - name: myapp-pod

23         image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1

24         imagePullPolicy: IfNotPresent

25         ports:

26           - containerPort: 80

27       # 指定节点标签选择，且标签存在

28       nodeSelector:

29         disk-type: ssd

运行yaml文件并查看信息

 1 [root@k8s-master scheduler]# kubectl apply -f scheduler_nodeSelector.yaml

 2 deployment.apps/scheduler-nodeselector-deploy created

 3 [root@k8s-master scheduler]#

 4 [root@k8s-master scheduler]# kubectl get deploy -o wide

 5 NAME                            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                      SELECTOR

 6 scheduler-nodeselector-deploy   5/5     5            5           10s   myapp-pod    registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp

 7 [root@k8s-master scheduler]#

 8 [root@k8s-master scheduler]# kubectl get rs -o wide

 9 NAME                                       DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES                                                      SELECTOR

10 scheduler-nodeselector-deploy-79455db454   5         5         5       14s   myapp-pod    registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp,pod-template-hash=79455db454

11 [root@k8s-master scheduler]#

12 [root@k8s-master scheduler]# kubectl get pod -o wide

13 NAME                                             READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES

14 scheduler-nodeselector-deploy-79455db454-745ph   1/1     Running   0          19s   10.244.4.154   k8s-node01   <none>           <none>

15 scheduler-nodeselector-deploy-79455db454-bmjvd   1/1     Running   0          19s   10.244.4.151   k8s-node01   <none>           <none>

16 scheduler-nodeselector-deploy-79455db454-g5cg2   1/1     Running   0          19s   10.244.4.153   k8s-node01   <none>           <none>

17 scheduler-nodeselector-deploy-79455db454-hw8jv   1/1     Running   0          19s   10.244.4.152   k8s-node01   <none>           <none>

18 scheduler-nodeselector-deploy-79455db454-zrt8d   1/1     Running   0          19s   10.244.4.155   k8s-node01   <none>           <none>

由上可见，所有pod都被调度到了k8s-node01节点。当然如果其他节点也有disk-type=ssd 标签，那么pod也会调度到这些节点上。

当nodeSelector标签不存在

要运行的yaml文件

 1 [root@k8s-master scheduler]# pwd

 2 /root/k8s_practice/scheduler

 3 [root@k8s-master scheduler]#

 4 [root@k8s-master scheduler]# cat scheduler_nodeSelector_02.yaml

 5 apiVersion: apps/v1

 6 kind: Deployment

 7 metadata:

 8   name: scheduler-nodeselector-deploy

 9   labels:

10     app: nodeselector-deploy

11 spec:

12   replicas: 5

13   selector:

14     matchLabels:

15       app: myapp

16   template:

17     metadata:

18       labels:

19         app: myapp

20     spec:

21       containers:

22       - name: myapp-pod

23         image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1

24         imagePullPolicy: IfNotPresent

25         ports:

26           - containerPort: 80

27       # 指定节点标签选择，且标签不存在

28       nodeSelector:

29         service-type: web

运行yaml文件并查看信息

 1 [root@k8s-master scheduler]# kubectl apply -f scheduler_nodeSelector_02.yaml

 2 deployment.apps/scheduler-nodeselector-deploy created

 3 [root@k8s-master scheduler]#

 4 [root@k8s-master scheduler]# kubectl get deploy -o wide

 5 NAME                            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                                      SELECTOR

 6 scheduler-nodeselector-deploy   0/5     5            0           26s   myapp-pod    registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp

 7 [root@k8s-master scheduler]#

 8 [root@k8s-master scheduler]# kubectl get rs -o wide

 9 NAME                                       DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES                                                      SELECTOR

10 scheduler-nodeselector-deploy-799d748db6   5         5         0       30s   myapp-pod    registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp,pod-template-hash=799d748db6

11 [root@k8s-master scheduler]#

12 [root@k8s-master scheduler]# kubectl get pod -o wide

13 NAME                                             READY   STATUS    RESTARTS   AGE   IP       NODE     NOMINATED NODE   READINESS GATES

14 scheduler-nodeselector-deploy-799d748db6-92mqj   0/1     Pending   0          40s   <none>   <none>   <none>           <none>

15 scheduler-nodeselector-deploy-799d748db6-c2w25   0/1     Pending   0          40s   <none>   <none>   <none>           <none>

16 scheduler-nodeselector-deploy-799d748db6-c8tlx   0/1     Pending   0          40s   <none>   <none>   <none>           <none>

17 scheduler-nodeselector-deploy-799d748db6-tc5n7   0/1     Pending   0          40s   <none>   <none>   <none>           <none>

18 scheduler-nodeselector-deploy-799d748db6-z8c57   0/1     Pending   0          40s   <none>   <none>   <none>           <none>

由上可见，如果nodeSelector匹配的标签不存在，则容器将不会运行，一直处于Pending 状态。

相关阅读

1、官网：Pod分配调度

2、Kubernetes K8S之调度器kube-scheduler详解

3、Kubernetes K8S之affinity亲和性与反亲和性详解与示例

4、Kubernetes K8S之Taints污点与Tolerations容忍详解

完毕！

———END———
如果觉得不错就关注下呗 (-^O^-) ！

Kubernetes K8S之固定节点nodeName和nodeSelector调度详解的更多相关文章

  1. Kubernetes K8S之通过helm部署metrics-server与HPA详解

    Kubernetes K8S之通过helm部署metrics-server与 Horizontal Pod Autoscaling (HPA)详解 主机配置规划 服务器名称(hostname) 系统版 ...

  2. Kubernetes服务pod的健康检测liveness和readiness详解

    Kubernetes服务pod的健康检测liveness和readiness详解 接下来给大家讲解下在K8S上,我们如果对我们的业务服务进行健康检测. Health Check.restartPoli ...

  3. kubernetes 亲和性调度详解

    文章目录 1 概述: 2 场景一:调度到一组具有相同特性的主机上(label+nodeSelector) 3 场景二:部署的应用不想调度到某些节点上(nodeaffinity) 4 场景三:部署的应用 ...

  4. k8s入坑之路（7）kubernetes设计精髓List/Watch机制和Informer模块详解

    1.list-watch是什么 List-watch 是 K8S 统一的异步消息处理机制,保证了消息的实时性,可靠性,顺序性,性能等等,为声明式风格的API 奠定了良好的基础,它是优雅的通信方式,是 ...

  5. 资深实践篇 | 基于Kubernetes 1.61的Kubernetes Scheduler 调度详解

    欢迎大家前往腾讯云技术社区,获取更多腾讯海量技术实践干货哦~ 作者:腾讯云容器服务团队 源码为 k8s v1.6.1 版本,github 上对应的 commit id 为 b0b7a323cc5a4a ...

  6. K8s 从懵圈到熟练 – 集群网络详解

    作者 | 声东 阿里云售后技术专家 导读:阿里云 K8S 集群网络目前有两种方案:一种是 flannel 方案:另外一种是基于 calico 和弹性网卡 eni 的 terway 方案.Terway ...

  7. ROS节点的初始化及退出详解（ros::init、SIGINT、ros::ok、ros::NodeHandle

    https://haoqchen.site/2018/04/28/ROS-node-init/ #include "ros/ros.h" #include <signal.h ...

  8. Kubernetes K8S之Ingress详解与示例

    K8S之Ingress概述与说明,并详解Ingress常用示例 主机配置规划 服务器名称(hostname) 系统版本 配置 内网IP 外网IP(模拟) k8s-master CentOS7.7 2C ...

  9. Kubernetes K8S之affinity亲和性与反亲和性详解与示例

    Kubernetes K8S之Node节点亲和性与反亲和性以及Pod亲和性与反亲和性详解与示例 主机配置规划 服务器名称(hostname) 系统版本 配置 内网IP 外网IP(模拟) k8s-mas ...

随机推荐

  1. C#5语法新特性

    C# 5.NET Framework 4.5 Visual Studio 2012 C#5.0新引进的语法基于.Net Framework 4.5.主要引进的语法:异步与等待,调用方信息 其中最重要的 ...

  2. 7_Reverse Integer

    7.Reverse Integer Given a 32-bit signed integer, reverse digits of an integer. Example 1: Input: 123 ...

  3. Spring Security 实战干货：客户端OAuth2授权请求的入口

    1. 前言 在Spring Security 实战干货:OAuth2第三方授权初体验一文中我先对OAuth2.0涉及的一些常用概念进行介绍,然后直接通过一个DEMO来让大家切身感受了OAuth2.0第 ...

  4. 7、Django之模型层第二篇：多表操作

    一 表关系回顾 在讲解MySQL时,我们提到,把应用程序的所有数据都放在一张表里是极不合理的. 比如我们开发一个员工管理系统,在数据库里只创建一张员工信息表,该表有四个字段:工号.姓名.部门名.部门职 ...

  5. Java项目——嗖嗖移动业务大厅

    嗖嗖移动业务大厅包类(如下图): SosoMgr: 1 package cn.biz; 2 3 import java.util.Scanner; 4 5 import cn.common.Commo ...

  6. Docker系列01—Docker 基础入门

    一.初识Docker和容器 1.1 什么是docker 容纳其他物品的工具,可以部分或完全封闭,被用于容纳.存储.运输物品.物体可以被放置在容器中,而容器则可以保护内容物. 容器? 容器就是在隔离的环 ...

  7. Sentinel 的一些小扩展

    随着微服务的流行,服务和服务之间的稳定性变得越来越重要.Sentinel 是面向分布式服务架构的流量控制组件,主要以流量为切入点,从流量控制.熔断降级.系统自适应保护等多个维度来帮助您保障微服务的稳定 ...

  8. 针对DEV XtraReport中没有radiobuttonlist的替代方法

     private void PrintingSystem_EditingFieldChanged(object sender, DevExpress.XtraPrinting.EditingField ...

  9. Jave正则的实现

    java的正则实现需要先导入 java.util.regex. java.util.regex 包主要包括以下三个类: Pattern 类: pattern 对象是一个正则表达式的编译表示.Patte ...

  10. Best Time to Buy and Sell Stock I II III IV

    一.Best Time to Buy and Sell Stock I Say you have an array for which the ith element is the price of ...