ci: deploy only on main branch

.gitlab-ci.yml

@@ -6,7 +6,6 @@ variables:
   ASTRO_URL:  "https://${CI_PROJECT_ROOT_NAMESPACE}.${CI_PAGES_DOMAIN}"
   ASTRO_BASE: "/${SUB_GROUP}/${CI_PROJECT_NAME}"
 
-
 pages:
   stage: deploy
   tags:
@@ -24,3 +23,9 @@ pages:
       # The folder that contains the built files to be published.
       # This must be called "public".
       - public
+  rules:
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
+  environment:
+    name: production
+    url: "${ASTRO_URL}${ASTRO_BASE}"
+