Using for Loops to repeat scaffolder steps

Template

Actions used

debug:log

You can check the available actions if you visit /templates/actions.

Walkthrough

Example Template

---
apiVersion: scaffolder.backstage.io/v1beta3
kind: Template
metadata:
   name: loop-template-example
   title: Loop through items to repeat a scaffolder step
   description: This scaffolder takes user input and loops through those into a log output.
spec:
   owner: roadie
   type: service
   parameters:
      properties:
         things:
            title: List of things
            type: array
            items:
               type: string
               title: A thing
   steps:
      - id: log-message
        name: Log Parsed Contents
        each: ${{ parameters.things }}
        action: debug:log
        input:
           message: "contents: ${{ each.value }}!"

Breakdown

Parameters

This section configures the frontend for your template. Essentially these values will be provided from the backstage ui to the template.

This renders a list of input fields where you can input a string value. The value of these string is stored into an array which is called things

   things:
      title: List of things
      type: array
      items:
         type: string
         title: A thing

Steps

debug:log

Logs the contents of the file which was parsed in the previous steps. Uses the form input things and outputs a debug log line for each value.

- id: log-message
  name: Log Parsed Contents
  each: ${{ parameters.things }}
  action: debug:log
  input:
    message: "contents: ${{ each.value }}!"