Assign Pods to Nodes using Node Affinity

    You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using or you can use one of these Kubernetes playgrounds:

    Your Kubernetes server must be at or later than version v1.10. To check the version, enter .

    1. List the nodes in your cluster, along with their labels:

      The output is similar to this:

      1. NAME      STATUS    ROLES    AGE     VERSION        LABELS
      2. worker0   Ready     <none>   1d      v1.13.0        ...,kubernetes.io/hostname=worker0
      3. worker1   Ready     <none>   1d      v1.13.0        ...,kubernetes.io/hostname=worker1
      4. worker2   Ready     <none>   1d      v1.13.0        ...,kubernetes.io/hostname=worker2

    2. Choose one of your nodes, and add a label to it:

      1. kubectl label nodes <your-node-name> disktype=ssd

      where <your-node-name> is the name of your chosen node.

      1. kubectl get nodes --show-labels

      The output is similar to this:

      In the preceding output, you can see that the worker0 node has a disktype=ssd label.

    This manifest describes a Pod that has a requiredDuringSchedulingIgnoredDuringExecution node affinity,disktype: ssd. This means that the pod will get scheduled only on a node that has a disktype=ssd label.

    pods/pod-nginx-required-affinity.yaml 

    1. apiVersion: v1
    2. kind: Pod
    3. metadata:
    4. spec:
    6.     nodeAffinity:
    7.       requiredDuringSchedulingIgnoredDuringExecution:
    8.         nodeSelectorTerms:
    9.         - matchExpressions:
    10.           - key: disktype
    11.             operator: In
    12.             values:
    13.             - ssd            
    14.   containers:
    15.   - name: nginx
    16.     image: nginx
    17.     imagePullPolicy: IfNotPresent

    1. Apply the manifest to create a Pod that is scheduled onto your chosen node:

      1. kubectl apply -f https://k8s.io/examples/pods/pod-nginx-required-affinity.yaml

    2. Verify that the pod is running on your chosen node:

      1. kubectl get pods --output=wide

    This manifest describes a Pod that has a preferredDuringSchedulingIgnoredDuringExecution node affinity,disktype: ssd. This means that the pod will prefer a node that has a disktype=ssd label.

    pods/pod-nginx-preferred-affinity.yaml Assign Pods to Nodes using Node Affinity - 图2

    1. apiVersion: v1
    2. metadata:
    3.   name: nginx
    4. spec:
    5.   affinity:
    6.     nodeAffinity:
    7.       preferredDuringSchedulingIgnoredDuringExecution:
    8.       - weight: 1
    9.         preference:
    10.           matchExpressions:
    11.           - key: disktype
    12.             operator: In
    13.             values:
    14.             - ssd          
    15.   containers:
    16.   - name: nginx
    17.     image: nginx
    18.     imagePullPolicy: IfNotPresent

    1. Apply the manifest to create a Pod that is scheduled onto your chosen node:

      1. kubectl apply -f https://k8s.io/examples/pods/pod-nginx-preferred-affinity.yaml

    Learn more about Node Affinity.