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

nodeName示例获取当前的节点信息复制代码1 [root@k8s-master scheduler]# kubectl get nodes -o wide2 NAMESTATUSROLESAGEVERSIONINTERNAL-IPEXTERNAL-IPOS-IMAGEKERNEL-VERSIONCONTAINER-RUNTIME3 k8s-masterReadymast

福伴

2570人浏览 · 2020-12-03 10:50:02

福伴 · 2020-12-03 10:50:02 发布

nodeName示例
获取当前的节点信息

复制代码
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 CentOS Linux 7 (Core) 3.10.0-1062.el7.x86_64 docker://19.3.8
4 k8s-node01 Ready 42d v1.17.4 172.16.1.111 CentOS Linux 7 (Core) 3.10.0-1062.el7.x86_64 docker://19.3.8
5 k8s-node02 Ready 42d v1.17.4 172.16.1.112 CentOS Linux 7 (Core) 3.10.0-1062.el7.x86_64 docker://19.3.8
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当nodeName指定节点存在
要运行的yaml文件

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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
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运行yaml文件并查看信息

复制代码
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
15 scheduler-nodename-deploy-d5c9574bd-c82cc 1/1 Running 0 23s 10.244.0.119 k8s-master
16 scheduler-nodename-deploy-d5c9574bd-dkkjg 1/1 Running 0 23s 10.244.0.122 k8s-master
17 scheduler-nodename-deploy-d5c9574bd-hcn77 1/1 Running 0 23s 10.244.0.121 k8s-master
18 scheduler-nodename-deploy-d5c9574bd-zstjx 1/1 Running 0 23s 10.244.0.120 k8s-master
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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

复制代码
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
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运行yaml文件并查看信息

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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 k8s-node08
15 scheduler-nodename-deploy-75944bdc5d-hfdlv 0/1 Pending 0 13s k8s-node08
16 scheduler-nodename-deploy-75944bdc5d-q9qgt 0/1 Pending 0 13s k8s-node08
17 scheduler-nodename-deploy-75944bdc5d-q9zl7 0/1 Pending 0 13s k8s-node08
18 scheduler-nodename-deploy-75944bdc5d-wxsnv 0/1 Pending 0 13s k8s-node08
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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

复制代码
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 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 42d v1.17.4 172.16.1.111 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 42d v1.17.4 172.16.1.112 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
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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。

复制代码
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 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 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
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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

复制代码
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
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运行yaml文件并查看信息

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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
15 scheduler-nodeselector-deploy-79455db454-bmjvd 1/1 Running 0 19s 10.244.4.151 k8s-node01
16 scheduler-nodeselector-deploy-79455db454-g5cg2 1/1 Running 0 19s 10.244.4.153 k8s-node01
17 scheduler-nodeselector-deploy-79455db454-hw8jv 1/1 Running 0 19s 10.244.4.152 k8s-node01
18 scheduler-nodeselector-deploy-79455db454-zrt8d 1/1 Running 0 19s 10.244.4.155 k8s-node01
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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

复制代码
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
复制代码

运行yaml文件并查看信息

复制代码
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
15 scheduler-nodeselector-deploy-799d748db6-c2w25 0/1 Pending 0 40s
16 scheduler-nodeselector-deploy-799d748db6-c8tlx 0/1 Pending 0 40s
17 scheduler-nodeselector-deploy-799d748db6-tc5n7 0/1 Pending 0 40s
18 scheduler-nodeselector-deploy-799d748db6-z8c57 0/1 Pending 0 40s
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