build(git): only deploy site if it's a new commit, fixes #3655

gulp-tasks/write-head.js

@@ -0,0 +1,18 @@
+const isProd = process.env.ELEVENTY_ENV === 'prod';
+
+/**
+ * Write the HEAD SHA to the `dist` on prod builds.
+ *
+ * @returns {Promise<void>}
+ */
+const writeHead = async () => {
+  if (isProd) {
+    const HEAD = require('child_process')
+      .execSync('git rev-parse HEAD')
+      .toString()
+      .trim();
+    require('fs').writeFileSync('./dist/HEAD', HEAD);
+  }
+};
+
+module.exports = writeHead;

gulpfile.js

@@ -21,6 +21,7 @@ const copyFonts = require('./gulp-tasks/copy-fonts.js');
 const copyGlobalImages = require('./gulp-tasks/copy-global-images.js');
 const copyMisc = require('./gulp-tasks/copy-misc.js');
 const sassTask = require('./gulp-tasks/sass.js');
+const writeHead = require('./gulp-tasks/write-head.js');
 
 gulp.task('copy-content-assets', copyContentAssets);
 gulp.task('default-locale', copyDefaultLocale);
@@ -35,6 +36,7 @@ gulp.task(
     copyContentAssets,
     copyFonts,
     sassTask,
+    writeHead,
   ),
 );