Check for broken links

.github/workflows/check-links.yaml

@@ -0,0 +1,39 @@
+# Check that all links are valid, i.e. not broken
+name: Check links
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  check-links:
+    runs-on: ubuntu-latest
+    env:
+      GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - uses: actions/checkout@v4
+
+      # The link checker will only work if mlc_config.json is a valid JSON
+      - name: Validate JSON
+        uses: docker://orrosenblatt/validate-json-action:latest
+        env:
+          INPUT_SCHEMA: .github/workflows/valid_json_schema.json
+          INPUT_JSONS: mlc_config.json
+
+      # These are status code that cannot be ignored.
+      #
+      # If there is a valid external link that fails,
+      # add it to mlc_config.json
+      - name: External links must be checked, do not allow '0' in the 'aliveStatusCodes' of mlc_config.json
+        run: if [[ $(grep --regexp "[^0-9]0[^0-9]" mlc_config.json | wc --lines) == "1" ]]; then echo "FOUND"; exit 42; fi
+
+      - name: Internal links must checked, do not allow '400' in the 'aliveStatusCodes' of mlc_config.json
+        run: if [[ $(grep --regexp "[^0-9]400[^0-9]" mlc_config.json | wc --lines) == "1" ]]; then echo "FOUND"; exit 42; fi
+
+
+      - uses: gaurav-nelson/github-action-markdown-link-check@v1
+        with:
+          config-file: 'mlc_config.json'
+          use-quiet-mode: 'yes'
+          use-verbose-mode: 'no'
+

.github/workflows/valid_json_schema.json

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+{
+    "properties": {
+        "foo": { "type": "string" },
+        "bar": { "type": "number" }
+    }
+}

mlc_config.json

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+{
+  "aliveStatusCodes": [200, 403, 418, 500, 503]
+}