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Adding your own Templates

Templates are stored in the Software Catalog under a kind Template. The minimum that is needed to define a template is a template.yaml file, but it would be good to also have some files in there that can be templated in.

A simple template.yaml definition might look something like this:

apiVersion: scaffolder.backstage.io/v1beta3
kind: Template
# some metadata about the template itself
metadata:
  name: v1beta3-demo
  title: Test Action template
  description: scaffolder v1beta3 template demo
spec:
  owner: backstage/techdocs-core
  type: service

  # these are the steps which are rendered in the frontend with the form input
  parameters:
    - title: Fill in some steps
      required:
        - name
      properties:
        name:
          title: Name
          type: string
          description: Unique name of the component
          ui:autofocus: true
          ui:options:
            rows: 5
    - title: Choose a location
      required:
        - repoUrl
      properties:
        repoUrl:
          title: Repository Location
          type: string
          ui:field: RepoUrlPicker
          ui:options:
            allowedHosts:
              - github.com

  # here's the steps that are executed in series in the scaffolder backend
  steps:
    - id: fetch-base
      name: Fetch Base
      action: fetch:template
      input:
        url: ./template
        values:
          name: ${{ parameters.name }}

    - id: fetch-docs
      name: Fetch Docs
      action: fetch:plain
      input:
        targetPath: ./community
        url: https://github.com/backstage/community/tree/main/backstage-community-sessions

    - id: publish
      name: Publish
      action: publish:github
      input:
        allowedHosts: ['github.com']
        description: This is ${{ parameters.name }}
        repoUrl: ${{ parameters.repoUrl }}

    - id: register
      name: Register
      action: catalog:register
      input:
        repoContentsUrl: ${{ steps['publish'].output.repoContentsUrl }}
        catalogInfoPath: '/catalog-info.yaml'

Template Entity contains more information about the required fields.

Once we have a template.yaml ready, we can then add it to the software catalog for use by the scaffolder.

Note: When you add or modify a template, you will need to refresh the location entity. Otherwise, Backstage won't display the template in the available templates, or it will keep showing the old template. You can refresh the location instance by going into Catalog web page, choosing Locations instead of Components, and selecting the correct location entity. From there, you can click on the refresh icon representing "Scheduled entity refresh" action. Afterwards, you should see your template updated.

You can add the template files to the catalog through static location configuration, for example:

catalog:
  locations:
    - type: url
      target: https://github.com/backstage/software-templates/blob/main/scaffolder-templates/react-ssr-template/template.yaml
      rules:
        - allow: [Template]
    - type: file
      target: template.yaml # Backstage will expect the file to be in packages/backend/template.yaml

Or you can add the template using the catalog-import plugin, which unless configured differently should be running on /catalog-import.

For information about writing your own templates, you can check out the docs here