为什么K8s的master节点不允许我们的业务Pod呢？

Name:               k8s-master
Roles:              master
Labels:             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=
                    type=k8s-master
Annotations:        flannel.alpha.coreos.com/backend-data: {"VtepMAC":"f2:45:d0:f1:05:49"}
                    flannel.alpha.coreos.com/backend-type: vxlan
                    flannel.alpha.coreos.com/kube-subnet-manager: true
                    flannel.alpha.coreos.com/public-ip: 192.168.1.2
                    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:  Tue, 28 Apr 2020 14:21:21 +0000
Taints:             node-role.kubernetes.io/master:NoSchedule
Unschedulable:      false
Lease:
  HolderIdentity:  k8s-master
  AcquireTime:     <unset>
  RenewTime:       Tue, 15 Dec 2020 01:52:20 +0000
Conditions:
  Type                 Status  LastHeartbeatTime                 LastTransitionTime                Reason                       Message
  ----                 ------  -----------------                 ------------------                ------                       -------
  NetworkUnavailable   False   Fri, 16 Oct 2020 09:38:22 +0000   Fri, 16 Oct 2020 09:38:22 +0000   FlannelIsUp                  Flannel is running on this node
  MemoryPressure       False   Tue, 15 Dec 2020 01:51:29 +0000   Fri, 08 May 2020 02:03:48 +0000   KubeletHasSufficientMemory   kubelet has sufficient memory available
  DiskPressure         False   Tue, 15 Dec 2020 01:51:29 +0000   Fri, 08 May 2020 02:03:48 +0000   KubeletHasNoDiskPressure     kubelet has no disk pressure
  PIDPressure          False   Tue, 15 Dec 2020 01:51:29 +0000   Fri, 08 May 2020 02:03:48 +0000   KubeletHasSufficientPID      kubelet has sufficient PID available
  Ready                True    Tue, 15 Dec 2020 01:51:29 +0000   Fri, 08 May 2020 02:03:56 +0000   KubeletReady                 kubelet is posting ready status
Addresses:
  InternalIP:  192.168.1.2
  Hostname:    k8s-master
Capacity:
  cpu:                4
  ephemeral-storage:  52417516Ki
  hugepages-2Mi:      0
  memory:             4045668Ki
  pods:               110
Allocatable:
  cpu:                4
  ephemeral-storage:  48307982666
  hugepages-2Mi:      0
  memory:             3943268Ki
  pods:               110
System Info:
  Machine ID:                 5003025f93c1a84914ea5ae66519c100
  System UUID:                AED4BF27-3256-4DF2-BFC6-8F4048D371F7
  Boot ID:                    986c348a-a3f0-4fe9-a68b-94b098739d14
  Kernel Version:             4.4.220-1.el7.elrepo.x86_64
  OS Image:                   CentOS Linux 7 (Core)
  Operating System:           linux
  Architecture:               amd64
  Container Runtime Version:  docker://19.3.8
  Kubelet Version:            v1.18.2
  Kube-Proxy Version:         v1.18.2
PodCIDR:                      10.244.0.0/24
PodCIDRs:                     10.244.0.0/24
Non-terminated Pods:          (18 in total)
  Namespace                   Name                                    CPU Requests  CPU Limits  Memory Requests  Memory Limits  AGE
  ---------                   ----                                    ------------  ----------  ---------------  -------------  ---
  kube-system                 etcd-k8s-master                         0 (0%)        0 (0%)      0 (0%)           0 (0%)         230d
  kube-system                 kube-apiserver-k8s-master               250m (6%)     0 (0%)      0 (0%)           0 (0%)         230d
  kube-system                 kube-controller-manager-k8s-master      200m (5%)     0 (0%)      0 (0%)           0 (0%)         230d
  kube-system                 kube-flannel-ds-amd64-56gdz             100m (2%)     100m (2%)   50Mi (1%)        50Mi (1%)      230d
  kube-system                 kube-proxy-kzcpg                        0 (0%)        0 (0%)      0 (0%)           0 (0%)         230d
  kube-system                 kube-scheduler-k8s-master               100m (2%)     0 (0%)      0 (0%)           0 (0%)         230d
  kube-system                 kuboard-pv-browser-fzbmd                0 (0%)        0 (0%)      0 (0%)           0 (0%)         28d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-5kdj7    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-6xd2w    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-72876    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-ctn78    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-jmdcr    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-pbxz2    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-pcnh7    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-pxdxd    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-rwnrh    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  kubernetes-dashboard        kubernetes-dashboard-d866db8ff-sbdtm    0 (0%)        0 (0%)      0 (0%)           0 (0%)         221d
  monitor-sa                  node-exporter-pptqr                     150m (3%)     0 (0%)      0 (0%)           0 (0%)         60d
Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  Resource           Requests    Limits
  --------           --------    ------
  cpu                800m (20%)  100m (2%)
  memory             50Mi (1%)   50Mi (1%)
  ephemeral-storage  0 (0%)      0 (0%)
  hugepages-2Mi      0 (0%)      0 (0%)
Events:              <none>

Taints:             node-role.kubernetes.io/master:NoSchedule