154 lines
4.6 KiB
Markdown
154 lines
4.6 KiB
Markdown
---
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title: Attach Traits
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---
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Traits in KubeVela can be attached to Helm based component seamlessly.
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In this sample application below, we add two traits, [scaler](https://github.com/oam-dev/kubevela/blob/master/charts/vela-core/templates/defwithtemplate/manualscale.yaml)
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and [virtualgroup](https://github.com/oam-dev/kubevela/blob/master/docs/examples/helm-module/virtual-group-td.yaml) to a Helm based component.
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```yaml
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apiVersion: core.oam.dev/v1beta1
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kind: Application
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metadata:
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name: myapp
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namespace: default
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spec:
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components:
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- name: demo-podinfo
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type: webapp-chart
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properties:
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image:
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tag: "5.1.2"
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traits:
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- type: scaler
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properties:
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replicas: 4
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- type: virtualgroup
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properties:
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group: "my-group1"
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type: "cluster"
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```
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> Note: when use traits with Helm based component, please *make sure the target workload in your Helm chart strictly follows the qualified-full-name convention in Helm.* [For example in this chart](https://github.com/captainroy-hy/podinfo/blob/c2b9603036f1f033ec2534ca0edee8eff8f5b335/charts/podinfo/templates/deployment.yaml#L4), the workload name is composed of [release name and chart name](https://github.com/captainroy-hy/podinfo/blob/c2b9603036f1f033ec2534ca0edee8eff8f5b335/charts/podinfo/templates/_helpers.tpl#L13).
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> This is because KubeVela relies on the name to discovery the workload, otherwise it cannot apply traits to the workload. KubeVela will generate a release name based on your `Application` name and component name automatically, so you need to make sure never override the full name template in your Helm chart.
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## Verify traits work correctly
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> You may need to wait a few seconds to check the trait attached because of reconciliation interval.
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Check the `scaler` trait takes effect.
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```shell
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$ kubectl get manualscalertrait
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NAME AGE
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demo-podinfo-scaler-d8f78c6fc 13m
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```
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```shell
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$ kubectl get deployment myapp-demo-podinfo -o json | jq .spec.replicas
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4
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```
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Check the `virtualgroup` trait.
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```shell
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$ kubectl get deployment myapp-demo-podinfo -o json | jq .spec.template.metadata.labels
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{
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"app.cluster.virtual.group": "my-group1",
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"app.kubernetes.io/name": "myapp-demo-podinfo"
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}
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```
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## Update Application
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After the application is deployed and workloads/traits are created successfully,
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you can update the application, and corresponding changes will be applied to the
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workload instances.
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Let's make several changes on the configuration of the sample application.
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```yaml
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apiVersion: core.oam.dev/v1beta1
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kind: Application
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metadata:
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name: myapp
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namespace: default
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spec:
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components:
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- name: demo-podinfo
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type: webapp-chart
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properties:
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image:
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tag: "5.1.3" # 5.1.2 => 5.1.3
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traits:
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- type: scaler
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properties:
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replicas: 2 # 4 => 2
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- type: virtualgroup
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properties:
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group: "my-group2" # my-group1 => my-group2
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type: "cluster"
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```
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Apply the new configuration and check the results after several minutes.
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Check the new values (`image.tag = 5.1.3`) from application's `properties` are assigned to the chart.
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```shell
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$ kubectl get deployment myapp-demo-podinfo -o json | jq '.spec.template.spec.containers[0].image'
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"ghcr.io/stefanprodan/podinfo:5.1.3"
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```
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Under the hood, Helm makes an upgrade to the release (revision 1 => 2).
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```shell
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$ helm ls -A
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NAME NAMESPACE REVISION UPDATED STATUS CHART APP VERSION
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myapp-demo-podinfo default 2 2021-03-15 08:52:00.037690148 +0000 UTC deployed podinfo-5.1.4 5.1.4
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```
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Check the `scaler` trait.
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```shell
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$ kubectl get deployment myapp-demo-podinfo -o json | jq .spec.replicas
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2
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```
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Check the `virtualgroup` trait.
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```shell
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$ kubectl get deployment myapp-demo-podinfo -o json | jq .spec.template.metadata.labels
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{
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"app.cluster.virtual.group": "my-group2",
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"app.kubernetes.io/name": "myapp-demo-podinfo"
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}
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```
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## Detach Trait
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Let's have a try detach a trait from the application.
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```yaml
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apiVersion: core.oam.dev/v1alpha2
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kind: Application
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metadata:
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name: myapp
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namespace: default
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spec:
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components:
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- name: demo-podinfo
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type: webapp-chart
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settings:
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image:
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tag: "5.1.3"
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traits:
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# - name: scaler
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# properties:
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# replicas: 2
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- name: virtualgroup
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properties:
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group: "my-group2"
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type: "cluster"
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```
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Apply the application and check `manualscalertrait` has been deleted.
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```shell
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$ kubectl get manualscalertrait
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No resources found
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```
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