Kubernetes Pod 调度

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环境信息

  • Centos 7
  • Kubernetes 1.24

污点和容忍度

默认情况下，集群中的 master 节点被设置成了污点，以确保只有控制平面的 Pod 才能调度部署到主节点上。

显示节点的污点信息

$ kubectl describe node k8s-master1
Name:               k8s-master1
Roles:              control-plane
Labels:             beta.kubernetes.io/arch=amd64
                    beta.kubernetes.io/os=linux
                    kubernetes.io/arch=amd64
                    kubernetes.io/hostname=k8s-master1
                    kubernetes.io/os=linux
                    node-role.kubernetes.io/control-plane=
                    node.kubernetes.io/exclude-from-external-load-balancers=
Annotations:        flannel.alpha.coreos.com/backend-data: {"VNI":1,"VtepMAC":"de:75:a4:67:58:1f"}
                    flannel.alpha.coreos.com/backend-type: vxlan
                    flannel.alpha.coreos.com/kube-subnet-manager: true
                    flannel.alpha.coreos.com/public-ip: 172.31.26.116
                    kubeadm.alpha.kubernetes.io/cri-socket: unix:///var/run/cri-dockerd.sock
                    management.cattle.io/pod-limits: {"cpu":"100m","memory":"390Mi"}
                    management.cattle.io/pod-requests: {"cpu":"950m","memory":"290Mi","pods":"8"}
                    node.alpha.kubernetes.io/ttl: 0
                    volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp:  Tue, 06 Dec 2022 17:50:49 +0800
Taints:             node-role.kubernetes.io/control-plane:NoSchedule
                    node-role.kubernetes.io/master:NoSchedule

Master 节点包含 2 个污点

  • node-role.kubernetes.io/control-plane:NoSchedule
  • node-role.kubernetes.io/master:NoSchedule

这 2 个污点将阻止 Pod 调度到这个节点上面，除非有 Pod 能够容忍这个污点(Taints)，通常能容忍这个污点的都是控制平面的 Pod。

查看 Pod 的容忍度

$ kubectl describe pod -n kube-system kube-proxy-2cslw
...
Tolerations:                 op=Exists
                             node.kubernetes.io/disk-pressure:NoSchedule op=Exists
                             node.kubernetes.io/memory-pressure:NoSchedule op=Exists
                             node.kubernetes.io/network-unavailable:NoSchedule op=Exists
                             node.kubernetes.io/not-ready:NoExecute op=Exists
                             node.kubernetes.io/pid-pressure:NoSchedule op=Exists
                             node.kubernetes.io/unreachable:NoExecute op=Exists
                             node.kubernetes.io/unschedulable:NoSchedule op=Exists
Events:                      <none>