Enable Gitlab CI to test buildability.

.gitlab-ci.yml

@@ -0,0 +1,29 @@
+variables:
+  GIT_SUBMODULE_STRATEGY: recursive
+
+image:
+  name: klakegg/hugo:0.55.6-ext-alpine
+  entrypoint:
+    - /bin/sh
+    - "-c"
+
+build:
+  script:
+    - hugo --minify
+  artifacts:
+    paths:
+      - public
+    expire_in: 3 months
+  only:
+    - master
+
+test:
+  script:
+    - hugo_output=$(hugo --path-warnings --i18n-warnings)
+    - echo "$hugo_output"
+    - if echo "$hugo_output" | grep -q 'i18n|MISSING_TRANSLATION'; then false; else true; fi
+    - if echo "$hugo_output" | grep -q 'WARN.*Duplicate target paths'; then false; else true; fi
+  artifacts:
+    paths:
+      - public
+    expire_in: 1 month