Kubernetes prohibits scheduling

In Kubernetes, you can prevent a Pod from being scheduled to a node in several ways. Here are some ways:

Node Selector : You can use Node Selector to restrict Pods to only be scheduled to nodes with specific labels. If you wish to completely disable pods from being scheduled to certain nodes, you can ensure that those nodes do not have the required labels, which will prevent pods from being scheduled to those nodes.

For example, to prohibit Pods from being scheduled on nodes with the label "nodename=forbidden", you can use the following configuration:

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  nodeSelector:
    nodename: forbidden
  containers:
  - name: my-container
    image: nginx

 This will cause the Pod to be scheduled only on nodes with the "nodename=forbidden" label. Without such a node, the Pod will not be scheduled.

Node Affinity : You can also use Node Affinity to control Pod scheduling more precisely. By defining Node Affinity rules, you can require Pods to run on specific nodes or avoid running on specific nodes.

For example, to prevent Pods from being scheduled to nodes with the label "nodename=forbidden", you can use the following configuration:

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: nodename
            operator: NotIn
            values:
            - forbidden
  containers:
  - name: my-container
    image: nginx

 This will require the Pod not to be scheduled on any node with the "nodename=forbidden" label.

Taints and Tolerations : Using Taints of nodes and Tolerations of Pods is also a common method to limit the scheduling of Pods. Taints on a node can make the node "poisonous", and only Pods with the corresponding Toleration can be scheduled on these nodes.

For example, to prevent Pods from being scheduled to nodes with "Taint", you can use the following configuration:

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  tolerations:
  - key: "example.com/taint-key"
    operator: "Exists"
    effect: "NoSchedule"
  containers:
  - name: my-container
    image: nginx

This will allow Pods with the corresponding Toleration to be scheduled on nodes with the corresponding Taint, but other Pods will be blocked from being scheduled.

Depending on your needs, you can choose a method that suits your situation to disable the scheduling of Pods to specific nodes. Each of the above methods has its own uses and scenarios.