Task: Check To See How Many Nodes Are Ready (not
The text discusses the concept of taints and tolerations in Kubernetes, which is a mechanism to ensure that pods are not placed on inappropriate nodes. Taints are added to nodes and specify conditions that must be met in order for a pod to be scheduled on that node. Tolerations are added to pods and specify which taints the pod is tolerant to. If there is no toleration matching a taint on a node, the pod will not be scheduled onto that node. The text also mentions the use of jsonpath to retrieve information about nodes and taints, as well as the NoSchedule and NoExecute taint effects which prevent pods from being scheduled or evicted on a node. Finally, the text discusses the TaintBasedEvictions feature, which allows nodes to be automatically untainted if they become unavailable.
To achieve this, you can use the following command to get the number of ready nodes (excluding nodes tainted with NoSchedule) and write the count to the file /home/ec2-user/cka/ready_nodes:
kubectl get nodes --field-selector=status.phase=Running -o jsonpath='{.items[?(@.spec.taints[?(@.effect!="NoSchedule")])].metadata.name}' | wc -w > /home/ec2-user/cka/ready_nodes
This command filters the nodes by their phase (Running) and checks for the presence of taints with effects other than NoSchedule. The number of selected nodes is then counted and written to the specified file.
If you have any other questions or need further assistance, feel free to ask!
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