Add .gitlab-ci.yml

.gitlab-ci.yml

+# This file is a template, and might need editing before it works on your project.
+# Full project: https://gitlab.com/pages/plain-html
+validate-pages:
+  stage: test
+  before_script:
+    - mkdir ~/validator
+    - apk add git python2 curl
+  script:
+    - >
+      for file in $(ls *.htm*); do
+          curl -H "Content-Type: text/html; charset=utf-8" --data-binary @$file https://validator.nu/?out=json
+       done
+