K8s系列之污点是什么？

什么是污点

污点（taints） 类似于宽容度的概念，例如master节点就有一个污点（taints），node节点就没有污点。

[root@master ~]# kubectl describe node master
Name: master
Roles: master
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.io/hostname=master
node-role.kubernetes.io/master=
Annotations: flannel.alpha.coreos.com/backend-data={"VtepMAC":"9a:3d:47:88:8f:80"}
flannel.alpha.coreos.com/backend-type=vxlan
flannel.alpha.coreos.com/kube-subnet-manager=true
flannel.alpha.coreos.com/public-ip=192.168.100.113
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, 26 Sep 2018 14:34:33 +0800
Taints: node-role.kubernetes.io/master:NoSchedule
[root@master ~]# kubectl describe node node1
Name: node1
Roles: <none>
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.iohostname=node1
Annotations: flannel.alpha.coreos.com/backend-data={"VtepMAC":"36:e6:76:83:f3:41"}
flannel.alpha.coreos.com/backend-type=vxlan
flannel.alpha.coreos.com/kube-subnet-manager=true
flannel.alpha.coreos.com/public-ip=192.168.100.238
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, 26 Sep 2018 14:45:14 +0800
Taints: <none>

这里的 node-role.kubernetes.io/master:NoSchedule 就是pod永远不会被调度至master上，以保证master上运行的都是系统级进程。