一，前言
上一篇，介绍了 k8s ConfigMap 管理服务环境变量；
本篇，介绍 k8s 污点和容忍度；
二，污点与容忍度介绍
通过污点和容忍度配置可以干预 Pod 部署到特定的节点；
比如：
不想让某些服务、deploy、pod 部署到某台机器上；
专门负责部署 mysql 的机器，可以设置污点默认不能部署其他服务；
污点和容忍度
- 在 Kubernetes 中， Pod 被部署到 Node 上面去的规则和逻辑是由 Kubernetes 的调度组件根据 Node 的剩余资源，地位，以及其他规则自动选择调度的
- 但前端和后端往往服务器资源的分配都是不均衡的，甚至有的服务只能让特定的服务器来跑
- 在这种情况下，我们选择自动调度是不均衡的，就需要人工去干预匹配选择规则了
- 这时候，就需要在给 Node 添加一个叫做污点的东西，以确保 Node 不被 Pod 调度到
- 当你给 Node 设置一个污点后，除非给 Pod 设置一个相对应的容忍度，否则 Pod 才能被调度上去。这也就是污点和容忍的来源
- 污点的格式是 key=value，可以自定义自己的内容，就像是一组 Tag 一样
- Node_Name 为要添加污点的 node 名称
- key 和 value 为一组键值对，代表一组标示标签
- NoSchedule 则为不被调度的意思，和它同级别的还有其他的值：PreferNoSchedule 和 NoExecute
三，清理环境
先清理一下现有环境，释放出资源：
[root@k8s-master deployment]# kubectl get pods
NAME READY STATUS RESTARTS AGE
pay-v1-655587b6f5-gv8hc 1/1 Running 0 24h
user-v1-9f4d589cc-rdmnz 1/1 Running 0 10m
v4-57b4cf7fd9-zcl45 0/1 ImagePullBackOff 0 5d23h
v4-fb4cd75f5-bf2pf 0/1 ImagePullBackOff 0 40h
// 删掉 pay-v1 的部署(pay-v1 的容器会被干掉)
[root@k8s-master deployment]# kubectl delete deploy pay-v1
deployment.apps "pay-v1" deleted
[root@k8s-master deployment]# kubectl get pods
NAME READY STATUS RESTARTS AGE
user-v1-9f4d589cc-rdmnz 1/1 Running 0 13m
v4-57b4cf7fd9-zcl45 0/1 ImagePullBackOff 0 5d23h
v4-fb4cd75f5-bf2pf 0/1 ImagePullBackOff 0 40h
四，设置污点
为k8s-node 设置污点：
kubectl taint nodes [Node_Name] [key]=[value]:NoSchedule
// 添加污点-k8s-nodes 不部署 pay-v1
[root@k8s-master deployment]# kubectl taint nodes k8s-node pay-v1=true:NoSchedule
node/k8s-node tainted
//查看污点
[root@k8s-master deployment]# kubectl describe node k8s-node
Name: k8s-node
Roles: <none>
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.io/arch=amd64
kubernetes.io/hostname=k8s-node
kubernetes.io/os=linux
Annotations: flannel.alpha.coreos.com/backend-data: {"VNI":1,"VtepMAC":"96:c0:15:7d:c1:a9"}
flannel.alpha.coreos.com/backend-type: vxlan
flannel.alpha.coreos.com/kube-subnet-manager: true
flannel.alpha.coreos.com/public-ip: 172.17.178.106
kubeadm.alpha.kubernetes.io/cri-socket: /var/run/dockershim.sock
node.alpha.kubernetes.io/ttl: 0
volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp: Wed, 22 Dec 2021 00:41:20 +0800
// 以下就是污点信息-如果部署的名称是 pay-v1，k8s-node 不参与调度
Taints: pay-v1=true:NoSchedule
Unschedulable: false
Lease:
HolderIdentity: k8s-node
AcquireTime: <unset>
RenewTime: Wed, 05 Jan 2022 15:35:38 +0800
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
NetworkUnavailable False Fri, 24 Dec 2021 17:43:49 +0800 Fri, 24 Dec 2021 17:43:49 +0800 FlannelIsUp Flannel is running on this node
MemoryPressure False Wed, 05 Jan 2022 15:32:38 +0800 Fri, 24 Dec 2021 18:22:47 +0800 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Wed, 05 Jan 2022 15:32:38 +0800 Fri, 24 Dec 2021 18:22:47 +0800 KubeletHasNoDiskPressure kubelet has no disk pressure
PIDPressure False Wed, 05 Jan 2022 15:32:38 +0800 Fri, 24 Dec 2021 18:22:47 +0800 KubeletHasSufficientPID kubelet has sufficient PID available
Ready True Wed, 05 Jan 2022 15:32:38 +0800 Fri, 24 Dec 2021 18:22:47 +0800 KubeletReady kubelet is posting ready status
Addresses:
InternalIP: 172.17.178.106
Hostname: k8s-node
Capacity:
cpu: 2
ephemeral-storage: 41152812Ki
hugepages-1Gi: 0
hugepages-2Mi: 0
memory: 951856Ki
pods: 110
Allocatable:
cpu: 2
ephemeral-storage: 37926431477
hugepages-1Gi: 0
hugepages-2Mi: 0
memory: 849456Ki
pods: 110
System Info:
Machine ID: 20211123171600472607520636465043
System UUID: 71F14756-1816-4DFF-86DF-5129F0234463
Boot ID: 336150f9-ea6b-4de6-b4f5-c06967b5b344
Kernel Version: 3.10.0-1160.45.1.el7.x86_64
OS Image: CentOS Linux 7 (Core)
Operating System: linux
Architecture: amd64
Container Runtime Version: docker://20.10.12
Kubelet Version: v1.20.4
Kube-Proxy Version: v1.20.4
PodCIDR: 10.244.1.0/24
PodCIDRs: 10.244.1.0/24
Non-terminated Pods: (6 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits AGE
--------- ---- ------------ ---------- --------------- ------------- ---
default user-v1-9f4d589cc-rdmnz 0 (0%) 0 (0%) 0 (0%) 0 (0%) 17m
default v4-57b4cf7fd9-zcl45 0 (0%) 0 (0%) 0 (0%) 0 (0%) 5d23h
default v4-fb4cd75f5-bf2pf 0 (0%) 0 (0%) 0 (0%) 0 (0%) 40h
ingress-nginx ingress-nginx-controller-6b6497d95d-9j7qn 100m (5%) 0 (0%) 90Mi (10%) 0 (0%) 13d
kube-system kube-flannel-ds-ckhq8 100m (5%) 100m (5%) 50Mi (6%) 50Mi (6%) 14d
kube-system kube-proxy-sp6r2 0 (0%) 0 (0%) 0 (0%) 0 (0%) 14d
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 200m (10%) 100m (5%)
memory 140Mi (16%) 50Mi (6%)
ephemeral-storage 0 (0%) 0 (0%)
hugepages-1Gi 0 (0%) 0 (0%)
hugepages-2Mi 0 (0%) 0 (0%)
Events: <none>
生效pay-v1 部署配置：deployment-pay-v1.yaml
[root@k8s-master deployment]# kubectl apply -f deployment-pay-v1.yaml
deployment.apps/pay-v1 created
[root@k8s-master deployment]# kubectl get pods
NAME READY STATUS RESTARTS AGE
pay-v1-655587b6f5-k26lx 0/1 Pending 0 19s
user-v1-9f4d589cc-rdmnz 1/1 Running 0 20m
v4-57b4cf7fd9-zcl45 0/1 ImagePullBackOff 0 5d23h
v4-fb4cd75f5-bf2pf 0/1 ImagePullBackOff 0 40h
新创建的pod：pay-v1-655587b6f5-k26lx 处于 Pending 状态：
[root@k8s-master deployment]# kubectl describe pod pay-v1-655587b6f5-k26lx
Name: pay-v1-655587b6f5-k26lx
Namespace: default
Priority: 0
Node: <none>
Labels: app=pay-v1
pod-template-hash=655587b6f5
Annotations: <none>
Status: Pending
IP:
IPs: <none>
Controlled By: ReplicaSet/pay-v1-655587b6f5
Containers:
nginx:
Image: nginx:pay
Port: 80/TCP
Host Port: 0/TCP
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-q4qxd (ro)
Conditions:
Type Status
PodScheduled False
Volumes:
default-token-q4qxd:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-q4qxd
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedScheduling 3s (x3 over 75s) default-scheduler 0/2 nodes are available: 1 node(s) had taint {node-role.kubernetes.io/master: }, that the pod didn't tolerate, 1 node(s) had taint {pay-v1: true}, that the pod didn't tolerate.
报错了，调度失败，共 2 个节点，0 个可用， k8s-node 污点效果生效
五，设置容忍度
为Pod 设置容忍度：
- 想让 Pod 被调度过去，需要在 Pod 一侧添加相同的容忍度才能被调度到
- 给 Pod 设置一组容忍度，以匹配对应的 Node 的污点
- key 和 value 是你配置 Node 污点的 key 和 value
- effect 是 Node 污点的调度效果，和 Node 的设置项也是匹配的
- operator 是运算符，equal 代表只有 key 和 value 相等才算数。当然也可以配置 exists ，代表只要 key 存在就匹配，不需要校验 value 的值
修改前： deployment-pay-v1.yaml
apiVersion: apps/v1 #API版本号
kind: Deployment #资源类型部署
metadata:
name: pay-v1 #资源名称
spec:
selector:
matchLabels:
app: pay-v1 #告诉deployment根据规则匹配相应的Pod进行控制和管理，matchLabels字段匹配Pod的label值
replicas: 1 #声明Pod副本的数量
template:
metadata:
labels:
app: pay-v1 #Pod名称
spec: #描述Pod内的容器信息
containers:
- name: nginx #容器的名称
image: nginx:pay #镜像
ports:
- containerPort: 80 #容器内映射的端口
修改后：
apiVersion: apps/v1 #API版本号
kind: Deployment #资源类型部署
metadata:
name: pay-v1 #资源名称
spec:
selector:
matchLabels:
app: pay-v1 #告诉deployment根据规则匹配相应的Pod进行控制和管理，matchLabels字段匹配Pod的label值
replicas: 1 #声明Pod副本的数量
template:
metadata:
labels:
app: pay-v1 #Pod名称
spec: #描述Pod内的容器信息
tolerations:
- key: "pay-v1"
value: "true"
operator: "Equal"
effect: "NoSchedule"
containers:
- name: nginx #容器的名称
image: nginx:pay #镜像
ports:
- containerPort: 80 #容器内映射的端口
生效配置：
[root@k8s-master deployment]# kubectl apply -f deployment-pay-v1.yaml
deployment.apps/pay-v1 configured
// pay-v1的 pod 成功 Running
[root@k8s-master deployment]# kubectl get pods
NAME READY STATUS RESTARTS AGE
pay-v1-6cd6d4cc78-sgvnv 1/1 Running 0 45s
user-v1-9f4d589cc-rdmnz 1/1 Running 0 86m
v4-57b4cf7fd9-zcl45 0/1 ImagePullBackOff 0 6d1h
v4-fb4cd75f5-bf2pf 0/1 ImagePullBackOff 0 42h
// 容忍污点，部署到了k8s-node上
[root@k8s-master deployment]# kubectl describe pod pay-v1-6cd6d4cc78-sgvnv
Name: pay-v1-6cd6d4cc78-sgvnv
Namespace: default
Priority: 0
Node: k8s-node/172.17.178.106
六，修改 node 节点的污点
先删除pay-v1 的部署
[root@k8s-master deployment]# kubectl delete deploy pay-v1
deployment.apps "pay-v1" deleted
// 之前是 pay-v1=true ，这次是 pay-v1=1
[root@k8s-master deployment]# kubectl taint nodes k8s-node pay-v1=1:NoSchedule --overwrite
node/k8s-node modified
[root@k8s-master deployment]# kubectl apply -f deployment-pay-v1.yaml
deployment.apps/pay-v1 created
// pending 了
[root@k8s-master deployment]# kubectl get pods
NAME READY STATUS RESTARTS AGE
pay-v1-6cd6d4cc78-shfp9 0/1 Pending 0 20s
user-v1-9f4d589cc-rdmnz 1/1 Running 0 91m
v4-57b4cf7fd9-zcl45 0/1 ImagePullBackOff 0 6d1h
v4-fb4cd75f5-bf2pf 0/1 ImagePullBackOff 0 42h
为什么是 pending 呢？因为污点不被允许；
这时因为，在 yaml 中的配置是：
spec: #描述Pod内的容器信息
tolerations:
- key: "pay-v1"
value: "true"
operator: "Equal"
effect: "NoSchedule"
key和 value 都要相等才可以，但 value 是 1，不相等；
修改：改为存在 key 即可，不关心 value 值
spec: #描述Pod内的容器信息
tolerations:
- key: "pay-v1"
operator: "Exists"
effect: "NoSchedule"
[root@k8s-master deployment]# vi deployment-pay-v1.yaml
apiVersion: apps/v1 #API版本号
kind: Deployment #资源类型部署
metadata:
name: pay-v1 #资源名称
spec:
selector:
matchLabels:
app: pay-v1 #告诉deployment根据规则匹配相应的Pod进行控制和管理，matchLabels字段匹配Pod的label值
replicas: 1 #声明Pod副本的数量
template:
metadata:
labels:
app: pay-v1 #Pod名称
spec: #描述Pod内的容器信息
tolerations:
- key: "pay-v1"
operator: "Exists"
effect: "NoSchedule"
containers:
- name: nginx #容器的名称
image: nginx:pay #镜像
ports:
- containerPort: 80 #容器内映射的端口
[root@k8s-master deployment]# kubectl apply -f deployment-pay-v1.yaml
deployment.apps/pay-v1 configured
// 成功 Running
[root@k8s-master deployment]# kubectl get pods
NAME READY STATUS RESTARTS AGE
pay-v1-6d6cdc544b-fbhdd 1/1 Running 0 28s
user-v1-9f4d589cc-rdmnz 1/1 Running 0 97m
v4-57b4cf7fd9-zcl45 0/1 ImagePullBackOff 0 6d1h
v4-fb4cd75f5-bf2pf 0/1 ImagePullBackOff 0 42h
即匹配规则可以自由指定，容忍规则也可以自由指定
七，删除 Node 的污点
kubectl taint nodes k8s-node pay-v1- // 最后的 - 就是删除的意思
[root@k8s-master ~]# kubectl taint nodes k8s-node pay-v1-
node/k8s-node untainted // 在k8s-node节点上取消污点
取消污点后，就可以随便部署了
八，如何在 master 上布署 pod
master 之所以不能部署 pod，是因为有污点
// 添加污点
[root@k8s-master ~]# kubectl taint nodes k8s-node pay-v1=true:NoSchedule --overwrite
node/k8s-node modified
// 删掉部署
[root@k8s-master ~]# kubectl delete deploy pay-v1
deployment.apps "pay-v1" deleted
// 查看k8s-master污点信息
[root@k8s-master ~]# kubectl describe node k8s-master
Name: k8s-master
Taints: node-role.kubernetes.io/master:NoSchedule
Unschedulable: false
修改pay-v1 配置，将 tolerations 容忍度，修改为 node-role.kubernetes.io/master，使之匹配
[root@k8s-master deployment]# vi deployment-pay-v1.yaml
apiVersion: apps/v1 #API版本号
kind: Deployment #资源类型部署
metadata:
name: pay-v1 #资源名称
spec:
selector:
matchLabels:
app: pay-v1 #告诉deployment根据规则匹配相应的Pod进行控制和管理，matchLabels字段匹配Pod的label值
replicas: 1 #声明Pod副本的数量
template:
metadata:
labels:
app: pay-v1 #Pod名称
spec: #描述Pod内的容器信息
+ tolerations:
+ - key: "node-role.kubernetes.io/master"
+ operator: "Exists"
+ effect: "NoSchedule"
containers:
- name: nginx #容器的名称
image: nginx:pay #镜像
ports:
- containerPort: 80 #容器内映射的端口
// 部署
[root@k8s-master deployment]# kubectl apply -f deployment-pay-v1.yaml
deployment.apps/pay-v1 created
查看部署 pod:
[root@k8s-master deployment]# kubectl get pods
NAME READY STATUS RESTARTS AGE
pay-v1-6db6455b8-np2hw 1/1 Running 0 37s
user-v1-9f4d589cc-rdmnz 1/1 Running 0 18h
v4-57b4cf7fd9-zcl45 0/1 ImagePullBackOff 0 6d17h
v4-fb4cd75f5-bf2pf 0/1 ImagePullBackOff 0 2d10h
[root@k8s-master deployment]# kubectl describe pod pay-v1-6db6455b8-np2hw
Name: pay-v1-6db6455b8-np2hw
Namespace: default
Priority: 0
Node: k8s-master/172.17.178.105
可以发现，pod 被部署到了 master 节点上
九，结尾
本篇，介绍了 k8s 污点和容忍度；
下一篇，待定；
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