Add yamllint to lefthook

lefthook.yml

@@ -18,6 +18,11 @@ pre-push:
       files: git diff --name-only --diff-filter=d $(git merge-base origin/master HEAD)..HEAD
       glob: 'doc/*.md'
       run: yarn markdownlint {files}
+    yamllint:
+      tags: backend style
+      files: git diff --name-only --diff-filter=d $(git merge-base origin/master HEAD)..HEAD
+      glob: '*.{yml,yaml}'
+      run: scripts/lint-yaml.sh {files}
     stylelint:
       tags: stylesheet css style
       files: git diff --name-only --diff-filter=d $(git merge-base origin/master HEAD)..HEAD

scripts/lint-yaml.sh

+#!/usr/bin/env bash
+
+set -euo pipefail
+
+if ! command -v yamllint > /dev/null; then
+  echo "ERROR: yamllint is not installed. For more information, see https://yamllint.readthedocs.io/en/stable/index.html."
+  exit 1
+fi
+
+yamllint --strict -f colored "$@"