PowerShell-master/.github/actions/infrastructure/markdownlinks/README.md

Verify Markdown Links Action

A GitHub composite action that verifies all links in markdown files using PowerShell and Markdig.

Features

• ✅ Parses markdown files using Markdig (built into PowerShell 7)
• ✅ Extracts all link types: inline links, reference links, and autolinks
• ✅ Verifies HTTP/HTTPS links with configurable timeouts and retries
• ✅ Validates local file references
• ✅ Supports excluding specific URL patterns
• ✅ Provides detailed error reporting with file locations
• ✅ Outputs metrics for CI/CD integration

Usage

Basic Usage

- name: Verify Markdown Links
  uses: ./.github/actions/infrastructure/markdownlinks
  with:
    path: './CHANGELOG'

Advanced Usage

- name: Verify Markdown Links
  uses: ./.github/actions/infrastructure/markdownlinks
  with:
    path: './docs'
    fail-on-error: 'true'
    timeout: 30
    max-retries: 2
    exclude-patterns: '*.example.com/*,*://localhost/*'

With Outputs

- name: Verify Markdown Links
  id: verify-links
  uses: ./.github/actions/infrastructure/markdownlinks
  with:
    path: './CHANGELOG'
    fail-on-error: 'false'

- name: Display Results
  run: |
    echo "Total links: ${{ steps.verify-links.outputs.total-links }}"
    echo "Passed: ${{ steps.verify-links.outputs.passed-links }}"
    echo "Failed: ${{ steps.verify-links.outputs.failed-links }}"
    echo "Skipped: ${{ steps.verify-links.outputs.skipped-links }}"

Inputs

Input	Description	Required	Default
path	Path to the directory containing markdown files to verify	No	./CHANGELOG
exclude-patterns	Comma-separated list of URL patterns to exclude from verification	No	''
fail-on-error	Whether to fail the action if any links are broken	No	true
timeout	Timeout in seconds for HTTP requests	No	30
max-retries	Maximum number of retries for failed requests	No	2

Outputs

Output	Description
total-links	Total number of unique links checked
passed-links	Number of links that passed verification
failed-links	Number of links that failed verification
skipped-links	Number of links that were skipped

Excluded Link Types

The action automatically skips the following link types:

• Anchor links (#section-name) - Would require full markdown parsing
• Email links (mailto:user@example.com) - Cannot be verified without sending email

GitHub Workflow Test

This section provides a workflow example and instructions for testing the link verification action.

Testing the Workflow

To test that the workflow properly detects broken links:

1. Make change to this file (e.g., this README.md file already contains one in the Broken Link Test section)
2. The workflow will run and should fail, reporting the broken link(s)
3. Revert your change to this file
4. Push again to verify the workflow passes

Example Workflow Configuration

name: Verify Links

on:
  push:
    branches: [ main ]
    paths:
      - '**/*.md'
  pull_request:
    branches: [ main ]
    paths:
      - '**/*.md'
  schedule:
    # Run weekly to catch external link rot
    - cron: '0 0 * * 0'

jobs:
  verify-links:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Verify CHANGELOG Links
        uses: ./.github/actions/infrastructure/markdownlinks
        with:
          path: './CHANGELOG'
          fail-on-error: 'true'

      - name: Verify Documentation Links
        uses: ./.github/actions/infrastructure/markdownlinks
        with:
          path: './docs'
          fail-on-error: 'false'
          exclude-patterns: '*.internal.example.com/*'

How It Works

1. Parse Markdown: Uses Parse-MarkdownLink.ps1 to extract all links from markdown files using Markdig
2. Deduplicate: Groups links by URL to avoid checking the same link multiple times
3. Verify Links:
   • HTTP/HTTPS links: Makes HEAD/GET requests with configurable timeout and retries
   • Local file references: Checks if the file exists relative to the markdown file
   • Excluded patterns: Skips links matching the exclude patterns
4. Report Results: Displays detailed results with file locations for failed links
5. Set Outputs: Provides metrics for downstream steps

Error Output Example

✗ FAILED: https://example.com/broken-link - HTTP 404
    Found in: /path/to/file.md:42:15
    Found in: /path/to/other.md:100:20

Link Verification Summary
============================================================
Total URLs checked: 150
Passed: 145
Failed: 2
Skipped: 3

Failed Links:
  • https://example.com/broken-link
    Error: HTTP 404
    Occurrences: 2

Requirements

• PowerShell 7+ (includes Markdig)
• Runs on: ubuntu-latest, windows-latest, macos-latest

Broken Link Test

• Broken Link

License

Same as the PowerShell repository.