Node Affinity

Using the CCE Console

1. Log in to the CCE console and choose Workloads > Deployments or Workloads > StatefulSets in the navigation pane.
2. Click a workload name in the Deployment or StatefulSet list. On the displayed workload details page, click the Scheduling Policies tab and then click Add Custom Scheduling Policy.
3. In the Node Affinity area, you can specify node labels to meet required or preferred rules in scheduling.

   Table 1 Node affinity settings

   Parameter	Description
   Required	It specifies a rule that must be met in scheduling. It corresponds to requiredDuringSchedulingIgnoredDuringExecution in Kubernetes. You can click Add Rule to add multiple required rules. A pod will be scheduled on a node that meets any of the rules configured.
   Preferred	It specifies a preference in scheduling. It corresponds to preferredDuringSchedulingIgnoredDuringExecution in Kubernetes. You can click Add Rule to add multiple preferred rules. The scheduler will try to enforce the rules but will not guarantee. If the scheduler cannot satisfy any one of the rules, the pod will still be scheduled.

4. Set a rule according to the following table. You can click Add Selector to configure multiple selectors for a rule.

   Table 2 Selector settings

   Parameter	Description
   Weight	This parameter is unavailable for a required rule. Set the weight of a preferred rule. A higher weight indicates a higher priority.
   Label	Node label. You can use the default label or customize a label.
   Operator	The following relations are supported: In, NotIn, Exists, DoesNotExist, Gt, and Lt
   Value	Tag value. Operators In and NotIn allow one or more label values. Values are separated with colons (;). Operators Exists and DoesNotExist are used to determine whether a label exists, and do not require a label value. If you set the operator to Gt or Lt for a label, the label value must be greater than or less than a certain integer.
   Operation	You can click Delete to delete a selector.
   Add Selector	A selector corresponds to matchExpressions in Kubernetes. You can click Add Selector to add multiple selectors for a scheduling rule. The rule is applied in scheduling only when all its selectors are satisfied.

   Figure 1 Node affinity scheduling policy
   

Using kubectl

This section uses Nginx as an example to describe how to configure node affinity.

Prerequisites

A workload that uses the nginx container image has been deployed on a node.

Procedure

Set Label to kubernetes.io/hostname, add affinity nodes, and set the operator to In. Then, click OK.

YAML file of the workload with node affinity:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx 
        imagePullPolicy: Always
        name: nginx
      imagePullSecrets:
      - name: default-secret
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
              - matchExpressions:
                  - key: kubernetes.io/hostname
                    operator: In
                    values:
                     - 192.168.6.174