ci: add megalinter workflows

- just copying from https://raw.githubusercontent.com/oxsecurity/megalinter/main/TEMPLATES/mega-linter.yml

.github/workflows/linter.yaml

@@ -0,0 +1,159 @@
+name: MegaLinter
+
+on:
+  pull_request:
+    branches:
+      - main
+
+env:
+  # Apply linter fixes configuration
+  #
+  # When active, APPLY_FIXES must also be defined as environment variable
+  # (in github/workflows/mega-linter.yml or other CI tool)
+  APPLY_FIXES: all
+
+  # Decide which event triggers application of fixes in a commit or a PR
+  # (pull_request, push, all)
+  APPLY_FIXES_EVENT: pull_request
+
+  # If APPLY_FIXES is used, defines if the fixes are directly committed (commit)
+  # or posted in a PR (pull_request)
+  APPLY_FIXES_MODE: commit
+
+concurrency:
+  group: ${{ github.ref }}-${{ github.workflow }}
+  cancel-in-progress: true
+
+jobs:
+  megalinter:
+    name: MegaLinter
+    runs-on: ubuntu-latest
+
+    # Give the default GITHUB_TOKEN write permission to commit and push, comment
+    # issues & post new PR; remove the ones you do not need
+    permissions:
+      contents: write
+      issues: write
+      pull-requests: write
+
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+        with:
+          token: ${{ secrets.PAT || secrets.GITHUB_TOKEN }}
+
+          # If you use VALIDATE_ALL_CODEBASE = true, you can remove this line to
+          # improve performance
+          fetch-depth: 0
+
+      # MegaLinter
+      - name: MegaLinter
+
+        # You can override MegaLinter flavor used to have faster performances
+        # More info at https://megalinter.io/flavors/
+        uses: oxsecurity/megalinter@v7
+
+        id: ml
+
+        # All available variables are described in documentation
+        # https://megalinter.io/configuration/
+        env:
+
+          # Validates all source when push on main, else just the git diff with
+          # main. Override with true if you always want to lint all sources
+          #
+          # To validate the entire codebase, set to:
+          # VALIDATE_ALL_CODEBASE: true
+          #
+          # To validate only diff with main, set to:
+          # VALIDATE_ALL_CODEBASE: >-
+          #   ${{
+          #     github.event_name == 'push' &&
+          #     contains(fromJSON('["refs/heads/main", "refs/heads/master"]'), github.ref)
+          #   }}
+          VALIDATE_ALL_CODEBASE: >-
+            ${{
+              github.event_name == 'push' &&
+              contains(fromJSON('["refs/heads/main", "refs/heads/master"]'), github.ref)
+            }}
+
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+          # ADD YOUR CUSTOM ENV VARIABLES HERE OR DEFINE THEM IN A FILE
+          # .mega-linter.yml AT THE ROOT OF YOUR REPOSITORY
+
+      # Upload MegaLinter artifacts
+      - name: Archive production artifacts
+        uses: actions/upload-artifact@v3
+        if: ${{ success() }} || ${{ failure() }}
+        with:
+          name: MegaLinter reports
+          path: |
+            megalinter-reports
+            mega-linter.log
+
+      # Set APPLY_FIXES_IF var for use in future steps
+      - name: Set APPLY_FIXES_IF var
+        run: |
+          printf 'APPLY_FIXES_IF=%s\n' "${{
+            steps.ml.outputs.has_updated_sources == 1 &&
+            (
+              env.APPLY_FIXES_EVENT == 'all' ||
+              env.APPLY_FIXES_EVENT == github.event_name
+            ) &&
+            (
+              github.event_name == 'push' ||
+              github.event.pull_request.head.repo.full_name == github.repository
+            )
+          }}" >> "${GITHUB_ENV}"
+
+      # Set APPLY_FIXES_IF_* vars for use in future steps
+      - name: Set APPLY_FIXES_IF_* vars
+        run: |
+          printf 'APPLY_FIXES_IF_PR=%s\n' "${{
+            env.APPLY_FIXES_IF == 'true' &&
+            env.APPLY_FIXES_MODE == 'pull_request'
+          }}" >> "${GITHUB_ENV}"
+          printf 'APPLY_FIXES_IF_COMMIT=%s\n' "${{
+            env.APPLY_FIXES_IF == 'true' &&
+            env.APPLY_FIXES_MODE == 'commit' &&
+            (!contains(fromJSON('["refs/heads/main", "refs/heads/master"]'), github.ref))
+          }}" >> "${GITHUB_ENV}"
+
+      # Create pull request if applicable
+      # (for now works only on PR from same repository, not from forks)
+      - name: Create Pull Request with applied fixes
+        uses: peter-evans/create-pull-request@v5
+        id: cpr
+        if: env.APPLY_FIXES_IF_PR == 'true'
+        with:
+          token: ${{ secrets.PAT || secrets.GITHUB_TOKEN }}
+          commit-message: "[MegaLinter] Apply linters automatic fixes"
+          title: "[MegaLinter] Apply linters automatic fixes"
+          labels: bot
+
+      - name: Create PR output
+        if: env.APPLY_FIXES_IF_PR == 'true'
+        run: |
+          echo "PR Number - ${{ steps.cpr.outputs.pull-request-number }}"
+          echo "PR URL - ${{ steps.cpr.outputs.pull-request-url }}"
+
+      # Push new commit if applicable
+      # (for now works only on PR from same repository, not from forks)
+      - name: Prepare commit
+        if: env.APPLY_FIXES_IF_COMMIT == 'true'
+        run: sudo chown -Rc $UID .git/
+
+      - name: Commit and push applied linter fixes
+        uses: stefanzweifel/git-auto-commit-action@v4
+        if: env.APPLY_FIXES_IF_COMMIT == 'true'
+        with:
+          branch: >-
+            ${{
+              github.event.pull_request.head.ref ||
+              github.head_ref ||
+              github.ref
+            }}
+          commit_message: "[MegaLinter] Apply linters fixes"
+          commit_user_name: megalinter-bot
+          commit_user_email: nicolas.vuillamy@ox.security