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Version: v1.0

How-to

In this section, it will introduce how to use raw K8s Object to declare app components via ComponentDefinition.

Before reading this part, please make sure you've learned the definition and template concepts.

Declare ComponentDefinition#

Here is a raw template based ComponentDefinition example which provides a abstraction for worker workload type:

apiVersion: core.oam.dev/v1beta1
kind: ComponentDefinition
metadata:
name: kube-worker
namespace: default
spec:
workload:
definition:
apiVersion: apps/v1
kind: Deployment
schematic:
kube:
template:
apiVersion: apps/v1
kind: Deployment
spec:
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
ports:
- containerPort: 80
parameters:
- name: image
required: true
type: string
fieldPaths:
- "spec.template.spec.containers[0].image"

In detail, the .spec.schematic.kube contains template of a workload resource and configurable parameters.

  • .spec.schematic.kube.template is the raw template in YAML format.
  • .spec.schematic.kube.parameters contains a set of configurable parameters. The name, type, and fieldPaths are required fields, description and required are optional fields.
    • The parameter name must be unique in a ComponentDefinition.
    • type indicates the data type of value set to the field. This is a required field which will help KubeVela to generate a OpenAPI JSON schema for the parameters automatically. In raw template, only basic data types are allowed, including string, number, and boolean, while array and object are not.
    • fieldPaths in the parameter specifies an array of fields within the template that will be overwritten by the value of this parameter. Fields are specified as JSON field paths without a leading dot, for example spec.replicas, spec.containers[0].image.

Declare an Application#

Here is an example Application.

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
name: myapp
namespace: default
spec:
components:
- name: mycomp
type: kube-worker
properties:
image: nginx:1.14.0

Since parameters only support basic data type, values in properties should be simple key-value, <parameterName>: <parameterValue>.

Deploy the Application and verify the running workload instance.

$ kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
mycomp 1/1 1 1 66m

And check the parameter works.

$ kubectl get deployment mycomp -o json | jq '.spec.template.spec.containers[0].image'
"nginx:1.14.0"
Last updated on by Jianbo Sun