Kubernetes: 10. Node Selector

Scheduler

By default Pods gets scheduled based on node availability for the scheduler
There may be cases where in one of the node has more resources and the pod required to be scheduled on this node
There are two ways to achieve this

Node Selector
Node Affinity

Node Selector

Update the pod definition file with the node selector label
Pod will be scheduled on the node matching the label
But first, Node has to be labelled.
Within the pod definition spec.nodeSelector is the property to map a pod to a node
With node selector, you can only have a simple key-value selection
There are no options for advanced selectors like label in certain values, or label not-in a value

pod-definition.yaml

apiVersion: v1
kind: Pod
metadata:
        name: myapp-pod
        labels:
                app: myapp

spec:
        containers:
            - name: nginx-container
                image: nginx

    
        nodeSelector:
                  size: Large

kubectl label node <node-name> <label-key>=<label-value> 
-> Set a node label with key value pair

kubectl label node node01 size=Large 
-> Set node01 label size to Large value

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