fix(ci/preview): add custom 404 page

OnkarRuikar · OnkarRuikar · commit a44664f821cd · 2025-01-23T16:36:11.000+05:30
diff --git a/.github/workflows/404.html b/.github/workflows/404.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<html>
+  <head>
+    <title>404 Page Not Found</title>
+    <script src="/en-US/_spas/404.js"></script>
+  </head>
+  <body>
+    <h1>404 Page Not Found</h1>
+  </body>
+</html>
diff --git a/.github/workflows/404.js b/.github/workflows/404.js
@@ -0,0 +1,8 @@
+window.addEventListener("DOMContentLoaded", () => {
+  if (document.location.hostname.endsWith("content.dev.mdn.mozit.cloud")) {
+    const link = document.createElement("a");
+    link.href = `https://developer.mozilla.org${location.pathname}`;
+    link.textContent = "View on MDN production server";
+    document.body.appendChild(link);
+  }
+});
diff --git a/.github/workflows/pr-test.yml b/.github/workflows/pr-test.yml
@@ -105,6 +105,11 @@ jobs:
           # Save the PR number into the build
           echo ${{ github.event.number }} > ${BUILD_OUT_ROOT}/NR
 
+          # Add the custom 404 page to provide production links to the unbuilt documents
+          mkdir -p ${BUILD_OUT_ROOT}/en-us/_spas/
+          cp -v ./.github/workflows/404.html ${BUILD_OUT_ROOT}/en-us/_spas/404.html
+          cp -v ./.github/workflows/404.js ${BUILD_OUT_ROOT}/en-us/_spas/404.js
+
           # Download the raw diff blob and store that inside the build
           # directory.
           # The purpose of this is for the PR Review Companion to later
