Kubernetes K8S之固定節點nodeName和nodeSelector調度詳解
Kubernetes K8S之固定節點nodeName和nodeSelector調度詳解與示例html
主機配置規劃
| 服務器名稱(hostname) | 系統版本 | 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是節點選擇約束的最簡單形式，可是因爲其限制，一般不多使用它。nodeName是PodSpec的領域。node
pod.spec.nodeName將Pod直接調度到指定的Node節點上，會【跳過Scheduler的調度策略】，該匹配規則是【強制】匹配。能夠越過Taints污點進行調度。linux
nodeName用於選擇節點的一些限制是：web
- 若是指定的節點不存在，則容器將不會運行，而且在某些狀況下可能會自動刪除。
- 若是指定的節點沒有足夠的資源來容納該Pod，則該Pod將會失敗，而且其緣由將被指出，例如OutOfmemory或OutOfcpu。
- 雲環境中的節點名稱並不是老是可預測或穩定的。
nodeName示例
獲取當前的節點信息docker
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
當nodeName指定節點存在
要運行的yaml文件api
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 # 指定節點運行 27 nodeName: k8s-master
運行yaml文件並查看信息服務器
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>
由上可見，yaml文件中nodeName: k8s-master生效，全部pod被調度到了k8s-master節點。若是這裏是nodeName: k8s-node02，那麼就會直接調度到k8s-node02節點。app
當nodeName指定節點不存在
要運行的yaml文件ide
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 # 指定節點運行，該節點不存在 27 nodeName: k8s-node08
運行yaml文件並查看信息google
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>
由上可見，若是指定的節點不存在，則容器將不會運行，一直處於Pending 狀態。
nodeSelector調度
nodeSelector是節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是經過Kubernetes的label-selector機制選擇節點，由調度器調度策略匹配label，然後調度Pod到目標節點，該匹配規則屬於【強制】約束。因爲是調度器調度，所以不能越過Taints污點進行調度。
nodeSelector示例
獲取當前的節點信息
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 <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標籤
運行kubectl get nodes以獲取羣集節點的名稱。而後能夠對指定節點添加標籤。好比：k8s-node01的磁盤爲SSD，那麼添加disk-type=ssd；k8s-node02的CPU核數高，那麼添加cpu-type=hight；若是爲Web機器，那麼添加service-type=web。怎麼添加標籤能夠根據實際規劃狀況而定。
1 ### 給k8s-node01 添加指定標籤 2 [root@k8s-master ~]# kubectl label nodes k8s-node01 disk-type=ssd 3 node/k8s-node01 labeled 4 #### 刪除標籤命令 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
由上可見，已經爲k8s-node01節點添加了disk-type=ssd 標籤。
當nodeSelector標籤存在
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 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 # 指定節點標籤選擇，且標籤存在 28 nodeSelector: 29 disk-type: ssd
運行yaml文件並查看信息
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>
由上可見，全部pod都被調度到了k8s-node01節點。固然若是其餘節點也有disk-type=ssd 標籤，那麼pod也會調度到這些節點上。
當nodeSelector標籤不存在
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 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 # 指定節點標籤選擇，且標籤不存在 28 nodeSelector: 29 service-type: web
運行yaml文件並查看信息
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>
由上可見，若是nodeSelector匹配的標籤不存在，則容器將不會運行，一直處於Pending 狀態。
相關閱讀
二、Kubernetes K8S之調度器kube-scheduler詳解
三、Kubernetes K8S之affinity親和性與反親和性詳解與示例
四、Kubernetes K8S之Taints污點與Tolerations容忍詳解
完畢！
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