Kubernetes K8S之固定節(jié)點nodeName和nodeSelector調度詳解

小仙女本仙人 2022-05-22 發(fā)布于北京

展開全文

Kubernetes K8S之固定節(jié)點nodeName和nodeSelector調度詳解與示例

主機配置規(guī)劃

服務器名稱(hostname)	系統(tǒng)版本	配置	內網IP	外網IP(模擬)
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調度

nodeName是節(jié)點選擇約束的最簡單形式，但是由于其限制，通常很少使用它。nodeName是PodSpec的領域。

pod.spec.nodeName將Pod直接調度到指定的Node節(jié)點上，會【跳過Scheduler的調度策略】，該匹配規(guī)則是【強制】匹配?？梢栽竭^Taints污點進行調度。

nodeName用于選擇節(jié)點的一些限制是：

如果指定的節(jié)點不存在，則容器將不會運行，并且在某些情況下可能會自動刪除。
如果指定的節(jié)點沒有足夠的資源來容納該Pod，則該Pod將會失敗，并且其原因將被指出，例如OutOfmemory或OutOfcpu。
云環(huán)境中的節(jié)點名稱并非總是可預測或穩(wěn)定的。

nodeName示例

獲取當前的節(jié)點信息

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. 172.16   。172.16 。 110     <無> CentOS Linux (Core)     3。el7.x 11062 .el7.x 1064 docker: // 19.3 - 4 k8s-node01 4.7.8 4 k8s-node01 4.8.7 <none> 22d v1. 17.4 172.16。1.111     <無> CentOS Linux 7（內核）    3.10 . 0 - 1062
    .el7.x86_64 docker: // 19.3.8 
5 k8s-node02 就緒 <none> 42d v1. 17.4    172.16。1.112    <無> CentOS Linux 7 (Core)    3.10。0 - 1062 .el7.x86_64 泊塢窗：// 19.3.8

當nodeName指定節(jié)點存在

要運行的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-節(jié)點名-部署
8個   標簽：
 9     應用程序：節(jié)點名-部署
10 規(guī)范：
 11   副本：5 
12   選擇器：
 13     匹配標簽：
 14       應用程序：myapp
 15   模板：
 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       # 指定節(jié)點運行
27       nodeName: k8s-master

運行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 節(jié)點 NOMINATED 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     運行   0           23s    10.244。0.122    k8s-master <none> <none>
 17 scheduler-nodename-deploy-d5c9574bd-hcn77    1 / 1     運行   0           23s    10.244。0.121    k8s-master <none> <none>
 18 scheduler-nodename-deploy-d5c9574bd-zstjx    1 / 1     運行   0           23s    10.244。0.120    k8s-master <無> <無>

由上可見，yaml文件中nodeName: k8s-master生效，所有pod被調度到了k8s-master節(jié)點。如果這里是nodeName: k8s-node02，那么就會直接調度到k8s-node02節(jié)點。

當nodeName指定節(jié)點不存在

要運行的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-節(jié)點名-部署
8個   標簽：
 9     應用程序：節(jié)點名-部署
10 規(guī)范：
 11   副本：5 
12   選擇器：
 13     匹配標簽：
 14       應用程序：myapp
 15   模板：
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       # 指定節(jié)點運行，該節(jié)點不存在
27       nodeName: k8s-node08

運行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寬
13 NAME READY STATUS RESTARTS AGE IP Node NOMINATED 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> <
無>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 <無> <無>

由上可見，如果指定的節(jié)點不存在，則容器將不會運行，一直處于Pending 狀態(tài)。

nodeSelector調度

nodeSelector是節(jié)點選擇約束的最簡單推薦形式。nodeSelector是PodSpec的領域。它指定鍵值對的映射。

Pod.spec.nodeSelector是通過Kubernetes的label-selector機制選擇節(jié)點，由調度器調度策略匹配label，而后調度Pod到目標節(jié)點，該匹配規(guī)則屬于【強制】約束。由于是調度器調度，因此不能越過Taints污點進行調度。

nodeSelector示例

獲取當前的節(jié)點信息

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    <無> CentOS Linux 7 (Core)    3.10。0 - 1062 .el7.x86_64 docker: // 19.3.8 beta./arch=amd64,beta./os=linux,/arch=amd64,/hostname=k8s-大師，/os=linux，node-role./master= 
4k8s-node01 就緒 <無> 42d v1. 17.4    172.16。1.111    <無> CentOS Linux 7 (Core)    3.10。0 - 1062 .el7.x86_64 docker: // 19.3.8 beta./arch=amd64,beta./os=linux,/arch=amd64,/hostname=k8s- node01,/os=linux 
5 k8s-node02 Ready <none> 42d v1. 17.4    172.16。1.112    <無> CentOS Linux 7 (Core)    3.10。0 - 1062 .el7.x86_64 泊塢窗：//19.3.8     beta./arch=amd64,beta./os=linux,/arch=amd64,/hostname=k8s-node02,/os=linux

添加label標簽

運行kubectl get nodes以獲取群集節(jié)點的名稱。然后可以對指定節(jié)點添加標簽。比如：k8s-node01的磁盤為SSD，那么添加disk-type=ssd；k8s-node02的CPU核數(shù)高，那么添加cpu-type=hight；如果為Web機器，那么添加service-type=web。怎么添加標簽可以根據(jù)實際規(guī)劃情況而定。

 1 ### 給k8s-node01 添加指定標簽
 2 [root@k8s-master ~]# kubectl label nodes k8s-node01 disk-type=ssd
 3 node/k8s-node01 labeled
 4 #### 刪除標簽命令 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./arch=amd64,beta./os=linux,/arch=amd64,/hostname=k8s-master,/os=linux,node-role./master=
 9 k8s-node01 Ready <none> 42d v1. 17.4    beta./arch=amd64,beta./os=linux,disk-type=ssd,/arch=amd64,/主機名=k8s-node01,/os = linux
 10 k8s-node02 就緒 <無> 42d v1。17.4    beta./arch=amd64,beta./os=linux,/arch=amd64,/主機名=k8s-node02,/os=linux

由上可見，已經為k8s-node01節(jié)點添加了disk-type=ssd 標簽。

當nodeSelector標簽存在

要運行的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種 ：部署
7 元數(shù)據(jù)：
 8   名稱：scheduler-nodeselector-部署
9   標簽：
 10     應用程序：nodeselector-部署
11 規(guī)范：
 12   副本：5 
13   選擇器：
 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       # 指定節(jié)點標簽選擇，且標簽存在
28       nodeSelector:
29         disk-type: ssd

運行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-主調度器]# 
  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寬
13 名稱就緒狀態(tài)重新啟動年齡 IP 節(jié)點提名節(jié)點就緒門
14 scheduler-nodeselector-deploy-79455db454-745ph    1 / 1     運行   0           19s    10.244。4.154    k8s-node01 <none> <none>
 15 scheduler-nodeselector-deploy-79455db454-bmjvd    1 / 1     運行   0           19s    10.244。4.151    k8s-node01 <none> <none>
 16調度程序-nodeselector-deploy-79455db454-g5cg2    1 /1     運行   0           19s    10.244。4.153 k8s    -node01 <none> <none>
 17 scheduler-nodeselector-deploy-79455db454-hw8jv    1 / 1     運行   0           19s    10.244。4.152    k8s-node01 <none> <none>
 18 scheduler-nodeselector-deploy-79455db454-zrt8d    1 / 1     運行   0           19s    10.244。4.155    k8s-node01 <無> <無>

由上可見，所有pod都被調度到了k8s-node01節(jié)點。當然如果其他節(jié)點也有disk-type=ssd 標簽，那么pod也會調度到這些節(jié)點上。

當nodeSelector標簽不存在

要運行的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種 ：部署
7 元數(shù)據(jù)：
 8   名稱：scheduler-nodeselector-部署
9   標簽：
 10     應用程序：nodeselector-部署
11 規(guī)范：
 12   副本：5 
13   選擇器：
 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       # 指定節(jié)點標簽選擇，且標簽不存在
28       nodeSelector:
29         service-type: web

運行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 -主調度程序]# 
  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寬
13  NAME READY STATUS RESTARTS AGE IP Node NOMINATED節(jié)點就緒
 門14 scheduler-nodeselector-deploy-799d748db6-92mqj     0 / 1      待定    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      等待    0            40s <無> <無> <無>
<無> 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> <無> <無> <無>