get that pages url

.gitlab-ci.yml

@@ -6,6 +6,7 @@ variables:
 build:
   stage: build
   script:
+    - CI=true
     - npm install
     - gatsby build --prefix-paths
   artifacts:

gatsby-config.js

 module.exports = {
-  pathPrefix:`.env.${process.env.CI_PAGES_URL}`,
+  pathPrefix: "${CI_PAGES_URL}",
   siteMetadata: {
     title: `Gatsby Default Starter`,
     description: `Kick off your next, great Gatsby project with this default starter. This barebones starter ships with the main Gatsby configuration files you might need.`,