Janik von Rotz

2 min read

Github Action for validating markdown links

GitHub Action are free computing resources to run CI/CD jobs that build, lint, test or deploy a software project. On the Awesome PowerShell I asked contributors to submit a PR for a quality check job. Not much later Frederik Hjorslev submitted a nice solution.

The first file he submitted was the script that analyzes any markdown file, extracts links and requests them.


function Test-MarkdownLinks([String]$Path) {
    $unreachable = @()
    # Get markdown files recursively
    $files = Get-ChildItem -Path $Path -Recurse -Include "*.md"

    $files | ForEach-Object {
        $fileName = $_.Name
        Write-Host "Analyzing $fileName"

        $urls = Select-String -Path $_ -Pattern "\[.+\]\((http.*?)\)" | ForEach-Object { $_.matches.Groups[1] } | Select-Object

        $urls | ForEach-Object {
            $url = $_.Value
            Write-Host "Requesting url $url"

            try {
                $request = Invoke-WebRequest -Uri $url
            } catch {
                Write-Warning -Message "Found dead url $url in $fileName"
                $unreachable += $url

    # Output urls
    return $unreachable

$DeadLinks = Test-MarkdownLinks -Path ".\readme.md"
if ($DeadLinks) {
    Write-Host -Object '--- DEAD LINKS FOUND ---' -ForegroundColor Red
    foreach ($DeadLink in $DeadLinks) {
        Write-Host -Object $DeadLink -ForegroundColor Red
    exit 1

Dead links are reported at the end and the scripts exit with 1 if one or more findings occured.

The other file he submitted is the GitHub Action configuration file.


# This is a basic workflow to help you get started with Actions

name: Quality Assurance

# Controls when the action will run. Triggers the workflow on push or pull request
# events but only for the master branch
    branches: [ master ]
  # * is a special character in YAML so you have to quote this string
  - cron:  '0 0 * * 0'

# A workflow run is made up of one or more jobs that can run sequentially or in parallel
    # The type of runner that the job will run on
    runs-on: ubuntu-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
      - uses: actions/checkout@v2

      - name: Analyze Links
        shell: pwsh
        run: |

This Action executes the the analyzer script every week and for every pull request. This ensures that contributors submit valid links.

Pretty neat. Thanks to all the Awesome PowerShell contributors.

Categories: Scripting
Tags: scripting , github , action , quality assurance
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