add lychee broken link approach

Author: mspiekermann

.github/workflows/.lycheeignore

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+# URL patterns to exclude from checking, one regex pattern per line
+# These links will be ignored by lychee
+
+# Example domains
+^https?://example\.com
+^https?://example\.org
+
+# Common temporary URLs or local development URLs
+^https?://localhost
+^https?://127\.0\.0\.1
+^https?://0\.0\.0\.0
+
+# Social media links (often have anti-scraping measures that may cause checks to fail)
+^https?://(www\.)?linkedin\.com
+^https?://(www\.)?twitter\.com
+^https?://(www\.)?facebook\.com
+
+# Files that may have restricted access
+\.pdf$
+
+# Local file paths that exist in production but not in CI environment
+file:///home/runner/work/eclipse-edc.github.io/eclipse-edc.github.io/content/en/images/edc.schematic.svg
+# Exclude all local SVG files as they may be processed during build
+file://.*\.svg$
+# Exclude content directory files which may be generated during build
+file://.*?/content/.*
+
+# GitHub specific patterns to reduce API rate limiting
+# These patterns are specifically for repositories that frequently cause 429 errors
+^https?://github\.com/git/git/blob/
+^https?://raw\.githubusercontent\.com/git/
+^https?://api\.github\.com/
+
+# Add project-specific URL patterns to exclude here

.github/workflows/check-broken-links.yaml

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+name: Check Broken Links
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  # Optional: Add scheduled checks
+  # schedule:
+  #   - cron: "0 0 * * 0"  # Runs once every Sunday
+
+jobs:
+  check-links:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      # Set up caching to reduce API requests
+      - name: Restore lychee cache
+        uses: actions/cache@v4
+        with:
+          path: .lycheecache
+          key: cache-lychee-${{ github.sha }}
+          restore-keys: cache-lychee-
+
+      - name: Setup link exclusion patterns (optional)
+        id: setup-exclude
+        run: |
+          if [ -f .lycheeignore ]; then
+            echo "Exclusion patterns found in .lycheeignore"
+          else
+            echo "# Add URL regex patterns to exclude, one per line" > .lycheeignore
+            echo "# Example: ^https://example.com" >> .lycheeignore
+          fi
+
+      - name: Link Checker
+        id: lychee
+        uses: lycheeverse/lychee-action@v2
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+        with:
+          args: >-
+            --cache
+            --max-cache-age 48h
+            --verbose
+            --no-progress
+            --exclude-path ".git"
+            --exclude-path "node_modules"
+            --max-retries 5
+            --timeout 30
+            --max-concurrency 8
+            --retry-wait-time 3
+            './**/*.md' 
+            './**/*.html' 
+            './**/*.txt'
+          fail: true
+          format: markdown
+          output: ./lychee-report.md
+
+      # If you want to post check results as PR comments, uncomment the following step
+      # - name: Create Comment
+      #   uses: peter-evans/create-or-update-comment@v3
+      #   if: github.event_name == 'pull_request' && steps.lychee.outputs.exit_code != 0
+      #   with:
+      #     issue-number: ${{ github.event.pull_request.number }}
+      #     body-file: ./lychee-report.md