Add a Caddyfile linting workflow

Author: QuLogic

.github/workflows/lint.yml

@@ -0,0 +1,39 @@
+name: Linting
+on: [pull_request]
+
+jobs:
+  caddyfmt:
+    name: caddyfmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install caddy
+        run: |
+          sudo apt install -y debian-keyring debian-archive-keyring apt-transport-https
+          curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/gpg.key' | \
+            sudo tee /etc/apt/trusted.gpg.d/caddy-stable.asc
+          curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/debian.deb.txt' | \
+            sudo tee /etc/apt/sources.list.d/caddy-stable.list
+          sudo apt update
+          sudo apt install caddy
+
+      - name: Set up reviewdog
+        run: |
+          mkdir -p "$HOME/bin"
+          curl -sfL \
+            https://github.com/reviewdog/reviewdog/raw/master/install.sh | \
+              sh -s -- -b "$HOME/bin"
+          echo "$HOME/bin" >> $GITHUB_PATH
+
+      - name: Run caddy validate
+        run: caddy validate
+
+      - name: Run caddy fmt
+        run: caddy fmt --overwrite
+
+      - name: Run reviewdog
+        uses: reviewdog/action-suggester@v1
+        with:
+          fail_on_error: true
+          tool_name: 'caddy fmt'