1、概述
在pod进行调度的时候，如果使用了节点的亲和性，那么就会在调度的时候，调度到具有某些标签的节点上，这个是从pod的角度来说的，同时呢，也可以从节点node的角度出发来定义什么样的pod可以被调度到这个节点上。
在k8s中，可以通过taints和toleration的一起使用来达到这个目的。
2、在节点上配置taints（污点）
2.1、语法
在节点上设置taints
kubectl taint nodes node1 key1=value1:NoSchedule移除节点上的taints
kubectl taint nodes node1 key1-注意：在key的最后面加上“-”
2.2、示例
2.2.1、在节点上设置taints
kubectl taint nodes nccztsjb-node-23 role=master:NoSchedule如果移除taints使用
kubectl taint nodes nccztsjb-node-23 role-2.2.2、查看节点上的taints信息
[root@nccztsjb-node-23 ~]# kubectl describe nodes nccztsjb-node-23 | grep Taints
Taints: role=master:NoSchedule
[root@nccztsjb-node-23 ~]# 说明节点上已经被配置了这个taints。那么任何的pod默认是不会被调度到这个节点上的。
2.2.3、创建pod（多个副本）
kubectl create deployment nginx-taints --image=172.20.58.152/middleware/nginx:1.21.4 --replicas=5查看pod的调度情况
[root@nccztsjb-node-23 ~]# kubectl get pod -l app=nginx-taints -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-taints-6698889db5-2sngj 1/1 Running 0 7s 172.39.157.221 nccztsjb-node-24 <none> <none>
nginx-taints-6698889db5-2t4nr 1/1 Running 0 7s 172.39.21.86 nccztsjb-node-25 <none> <none>
nginx-taints-6698889db5-jjbwn 1/1 Running 0 7s 172.39.21.85 nccztsjb-node-25 <none> <none>
nginx-taints-6698889db5-ljdlf 1/1 Running 0 7s 172.39.157.223 nccztsjb-node-24 <none> <none>
nginx-taints-6698889db5-mtds6 1/1 Running 0 7s 172.39.157.222 nccztsjb-node-24 <none> <none>
[root@nccztsjb-node-23 ~]# 从查询的结果来看，pod没有被调度到nccztsjb-node-23的节点上。
那要让某些的pod被调度到这个节点上该怎么做呢？
继续往下看toleration的内容。
3、pod上设置toleration（容忍）
所谓的toleration即pod允许、容忍某些节点，可以进行调度。
那，我们看到，在2.2.3的步骤中，pod是不会在节点nccztsjb-node-23上进行发布的，那么要在这个节点上进行调度该如何操作呢？
就是要在pod上定义toleration。
3.1、语法
(1)operator: equal
tolerations:
- key: "key1"
operator: "Equal"
value: "value1"
effect: "NoSchedule"注意，如果operator如果是Equal，那么就要定义key和value，并且要和taints设置的值是一样的。
（2）operator: exists
tolerations:
- key: "key1"
operator: "Exists"
effect: "NoSchedule"如果operator是exists的，那么就不需要设置value的值。
(3)operator为exists，但是不设置key
tolerations:
- operator: "Exists"
effect: "NoSchedule"3.2、示例
(1) operator为euqal的情况
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-taints
namespace: default
spec:
progressDeadlineSeconds: 600
selector:
matchLabels:
app: nginx-taints
replicas: 5
template:
metadata:
labels:
app: nginx-taints
spec:
containers:
- image: 172.20.58.152/middleware/nginx:1.21.4
imagePullPolicy: IfNotPresent
name: nginx
dnsPolicy: ClusterFirst
restartPolicy: Always
tolerations:
- key: "role"
operator: "Equal"
value: "master"
effect: "NoSchedule"创建deployment
kubectl replace -f nginx-taints.yaml
[root@nccztsjb-node-23 ~]# kubectl get pod -l app=nginx-taints -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-taints-58b6ddd798-6dstj 1/1 Running 0 28s 172.39.21.84 nccztsjb-node-25 <none> <none>
nginx-taints-58b6ddd798-dm9nn 1/1 Running 0 26s 172.39.157.225 nccztsjb-node-24 <none> <none>
nginx-taints-58b6ddd798-ptm5m 1/1 Running 0 28s 172.39.157.224 nccztsjb-node-24 <none> <none>
nginx-taints-58b6ddd798-rxgcg 1/1 Running 0 26s 172.39.21.92 nccztsjb-node-25 <none> <none>
nginx-taints-58b6ddd798-ztnvb 1/1 Running 0 28s 172.39.209.74 nccztsjb-node-23 <none> <none>发现在重新应用了yaml之后，是可以在nccztsjb-node-23节点上进行pod的调度的。
(2)operator为exists的情况
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-taints
namespace: default
spec:
progressDeadlineSeconds: 600
selector:
matchLabels:
app: nginx-taints
replicas: 5
template:
metadata:
labels:
app: nginx-taints
spec:
containers:
- image: 172.20.58.152/middleware/nginx:1.21.4
imagePullPolicy: IfNotPresent
name: nginx
dnsPolicy: ClusterFirst
restartPolicy: Always
tolerations:
- key: "role"
operator: "Exists"
effect: "NoSchedule"重新应用yaml
[root@nccztsjb-node-23 ~]# kubectl replace -f nginx-taints.yaml
deployment.apps/nginx-taints replaced
[root@nccztsjb-node-23 ~]# kubectl get pod -l app=nginx-taints -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-taints-6cb85bb844-6b8kr 1/1 Running 0 13s 172.39.157.226 nccztsjb-node-24 <none> <none>
nginx-taints-6cb85bb844-k72xc 1/1 Running 0 13s 172.39.21.93 nccztsjb-node-25 <none> <none>
nginx-taints-6cb85bb844-ql2zh 1/1 Running 0 11s 172.39.157.227 nccztsjb-node-24 <none> <none>
nginx-taints-6cb85bb844-s48z8 1/1 Running 0 11s 172.39.21.90 nccztsjb-node-25 <none> <none>
nginx-taints-6cb85bb844-wwwhb 1/1 Running 0 13s 172.39.209.75 nccztsjb-node-23 <none> <none>也一样是可以在节点nccztsjb-node-23上进行调度的。
OK，以上就是在node上设置tanints，默认没有任何的pod会被调度到该节点上，然后通过在pod上设置toleration允许pod被调度到这个节点上。注意：是允许、能够被调度到这个节点上，不是一定、必须调度到这个节点上（比如在有多个节点的情况下，其他的节点没有taints的设置是可以允许被调度上的）
(3)不设置key和value的场景
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-taints
namespace: default
spec:
progressDeadlineSeconds: 600
selector:
matchLabels:
app: nginx-taints
replicas: 5
template:
metadata:
labels:
app: nginx-taints
spec:
containers:
- image: 172.20.58.152/middleware/nginx:1.21.4
imagePullPolicy: IfNotPresent
name: nginx
dnsPolicy: ClusterFirst
restartPolicy: Always
tolerations:
- operator: "Exists"
effect: "NoSchedule"重新应用配置yaml
[root@nccztsjb-node-23 ~]# kubectl apply -f nginx-taints.yaml
deployment.apps/nginx-taints created
[root@nccztsjb-node-23 ~]# kubectl get pod -l app=nginx-taints -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-taints-548544bcdd-2ftwq 1/1 Running 0 10s 172.39.209.76 nccztsjb-node-23 <none> <none>
nginx-taints-548544bcdd-6wvtp 1/1 Running 0 10s 172.39.157.229 nccztsjb-node-24 <none> <none>
nginx-taints-548544bcdd-glbkv 1/1 Running 0 10s 172.39.21.89 nccztsjb-node-25 <none> <none>
nginx-taints-548544bcdd-gn6wp 1/1 Running 0 10s 172.39.21.91 nccztsjb-node-25 <none> <none>
nginx-taints-548544bcdd-kdkfx 1/1 Running 0 10s 172.39.157.228 nccztsjb-node-24 <none> <none>
[root@nccztsjb-node-23 ~]# 可以发现，pod还是依然可以被调度到节点nccztsjb-node-23上的。即如果没有key,value，将operator设置为exists是一样的效果。这个设置可以容忍任何的taints.
3.3、effect可以取哪些值
- NoSchedule
- PreferNoSchedule
- NoExecure
4、核心关注
- taints定义在node上，拒绝pod的运行
- toleration定义在pod上，让pod能够运行在标注了taint的node上。
taints的主要目标：让pod避开那些不合适的node. (不合适的node标注上taints)