kubevela.github.io/docs/kube/trait.md

title
Attach Traits

All traits in the KubeVela system works well with the Raw K8s Object 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"
}