YAML for k8s (Incomplete)

Deployment YAML file for k8s

Deployment of application in chosen nodes

Using Node Affinity

Label Nodes:

Label your desired nodes. For example:

  kubectl label nodes node1 mylabel=selected
  kubectl label nodes node2 mylabel=selected

Create a Deployment YAML file (deployment.yaml):

  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: my-deployment
  spec:
    replicas: 2
    selector:
      matchLabels:
        app: my-app
    template:
      metadata:
        labels:
          app: my-app
      spec:
        affinity:
          nodeAffinity:
            requiredDuringSchedulingIgnoredDuringExecution:
              nodeSelectorTerms:
              - matchExpressions:
                - key: mylabel
                  operator: In
                  values:
                  - selected
        containers:
        - name: my-container
          image: nginx

Apply the Deployment:

Apply the deployment using the following command:
```
  kubectl apply -f deployment.yaml
```

Labels: You label the nodes you want to target. In this example, both node1 and node2 are labeled with mylabel=selected.

Affinity: The nodeAffinity field is used to specify that the pods should be scheduled on nodes with the label mylabel set to selected. The requiredDuringSchedulingIgnoredDuringExecution field ensures that the scheduler will only place pods on nodes that match this condition.

Deployment Spec: The deployment spec ensures that 2 replicas of the pods are created and scheduled only on the labeled nodes.

Using Node Selector

If you want to target multiple nodes using nodeSelector, you can label both nodes with the same label and then specify that label in your pod or deployment spec.

Label Nodes:

Label your desired nodes. For example:

  kubectl label nodes node1 mylabel=selected
  kubectl label nodes node2 mylabel=selected

Create a Deployment YAML file (deployment.yaml):

  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: my-deployment
  spec:
    replicas: 2
    selector:
      matchLabels:
        app: my-app
    template:
      metadata:
        labels:
          app: my-app
      spec:
        nodeSelector:
          mylabel: selected
        containers:
        - name: my-container
          image: nginx

Apply the Deployment:

Apply the deployment using the following command:
```
  kubectl apply -f deployment.yaml
```

Labels: You label the nodes you want to target. In this example, both node1 and node2 are labeled with mylabel=selected.

Node Selector: The nodeSelector field is used to specify that the pods should be scheduled on nodes with the label mylabel set to selected. This is a straightforward way to ensure that pods are only scheduled on nodes with the matching label.

Deployment Spec: The deployment spec ensures that 2 replicas of the pods are created and scheduled only on the labeled nodes.

Using nodeSelector is simpler but less flexible compared to nodeAffinity. If your requirements are straightforward and you only need to match pods to nodes with specific labels, nodeSelector is sufficient. If you need more complex scheduling rules, such as preferred or multiple conditions, then nodeAffinity is the better choice.