kubevela.github.io/docs/platform-engineers/kube/trait.md

title
Attach Traits

All traits in the KubeVela system works well with the simple template based Component.

In this sample, we will attach two traits, scaler and virtualgroup to a component

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  name: myapp
  namespace: default
spec:
  components:
    - name: mycomp
      type: kube-worker
      properties: 
        image: nginx:1.14.0
      traits:
        - type: scaler
          properties:
            replicas: 2
        - type: virtualgroup
          properties:
            group: "my-group1"
            type: "cluster"

Verify

Deploy the application and verify traits work.

Check the scaler trait.

kubectl get manualscalertrait

NAME                            AGE
demo-podinfo-scaler-3x1sfcd34   2m

kubectl get deployment mycomp -o json | jq .spec.replicas

2

Check the virtualgroup trait.

kubectl get deployment mycomp -o json | jq .spec.template.metadata.labels

{
  "app.cluster.virtual.group": "my-group1",
  "app.kubernetes.io/name": "myapp"
}

Update an Application

After the application is deployed and workloads/traits are created successfully, you can update the application, and corresponding changes will be applied to the workload.

Let's make several changes on the configuration of the sample application.

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  name: myapp
  namespace: default
spec:
  components:
    - name: mycomp
      type: kube-worker
      properties: 
        image: nginx:1.14.1 # 1.14.0 => 1.14.1
      traits:
        - type: scaler
          properties:
            replicas: 4 # 2 => 4
        - type: virtualgroup
          properties:
            group: "my-group2" # my-group1 => my-group2
            type: "cluster"

Apply the new configuration and check the results after several seconds.

After updating, the workload instance name will be updated from mycomp-v1 to mycomp-v2.

Check the new property value.

kubectl get deployment mycomp -o json | jq '.spec.template.spec.containers[0].image'

"nginx:1.14.1"

Check the scaler trait.

kubectl get deployment mycomp -o json | jq .spec.replicas

4

Check the virtualgroup trait.

kubectl get deployment mycomp -o json | jq .spec.template.metadata.labels

{
  "app.cluster.virtual.group": "my-group2",
  "app.kubernetes.io/name": "myapp"
}