Malnati/templateer

A simple engine to render templates in GitHub Actions using environment variables.

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What it is

Templateer is a GitHub composite action that renders template files using envsubst based on environment variables available in the GitHub Actions step/job.

• Accepts template and result
• Optionally prints exported variables via debug=true
• Produces outputs: path and body

How it works

1. Exports environment variables to $GITHUB_ENV (except those starting with GITHUB_)
2. Runs envsubst to replace placeholders (e.g., $VAR) in the template
3. Publishes the rendered file path and rendered content as outputs

Inputs

Input	Required	Default	Description
template	Yes	-	Template file path
result	Yes	-	Rendered output file path
debug	No	false	If true, prints exported variables to logs

Outputs

Output	Description
path	Rendered file path
body	Rendered content (multiline)

Usage example

1) Template

# .github/templates/report.md
Hello, $NAME.

File: $FILE_NAME
Repository: $GITHUB_REPOSITORY

2) Workflow

# .github/workflows/example.yml
name: templateer-example

on:
  workflow_dispatch:

jobs:
  render:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Render template
        id: tpl
        uses: Malnati/templateer@v1.0.0
        env:
          NAME: Ricardo
          FILE_NAME: .reports/20251215-0100_hardcode.json
        with:
          template: .github/templates/report.md
          result: /tmp/report.rendered.md

      - name: Print path
        shell: bash
        run: echo "${{ steps.tpl.outputs.path }}"

      - name: Print content
        shell: bash
        run: |
          echo "-----"
          echo "${{ steps.tpl.outputs.body }}"
          echo "-----"

Template rules

• Use placeholders in the $VAR format (standard envsubst syntax).
• Variables can come from env: at the step/job level, or from previous steps via $GITHUB_ENV.

Limitations

• envsubst only replaces environment variables; it does not support conditional logic.
• If a variable does not exist, the placeholder may become empty in the rendered output.

License

See LICENSE.