kubevela.github.io/docs/platform-engineers/workflow/steps.md

title
Steps

What's a Step

A Workflow Step instantiates from a Definition and runs the instance. It corresponds to find a Definition by the type field:

apiVersion: core.oam.dev/v1beta1
kind: Application
spec:
  ...
  workflow:
    steps:
      - name: deploy-server1
        # This is the name of the Definition to actually create an executable instance
        type: apply-component
        properties:
          component: server1
          ...

How to define a Step

The platform admin prepares the WorkflowStepDefinitions for developers to use. Basically the Definition provides the templated process to automate operation tasks. This hides the complexities and exposes only high-level parameters to simplify user experience. Here's an example of a Definition:

apiVersion: core.oam.dev/v1beta1
kind: WorkflowStepDefinition
metadata:
  name: apply-component
spec:
  schematic:
    cue:
      template: |
        import ("vela/op")
        parameter: {
           component: string
           prefixIP?: string
        }
        // load component from application
        component: op.#Load & {
           component: parameter.component
        }
        // apply workload to Kubernetes cluster
        apply: op.#ApplyComponent & {
           component: parameter.component
        }
        // wait until workload.status equal "Running"
        wait: op.#ConditionalWait & {
           continue: apply.workload.status.phase =="Running"
        }
        // export podIP
        myIP: apply.workload.status.podIP        

User Parameters

Inside the CUE template, the parameters exposed to users are defined in the parameters key. The workflow step properties from the Application will be used to fill the parameters. Besides properties, we also support data flow to input parameter values from outputs of other steps.

CUE Actions

The rest of CUE keys are actions that will be executed in order by KubeVela. To learn about how to compose such actions, read CUE Actions Reference