Add antora-ui-version meta element

Used to test

rm -rf build; gulp bundle && cat public/_/partials/head-meta.hbs && unzip -q build/*.zip -d build && cat build/partials/head-meta.hbs

Closes gh-245

gulp.d/tasks/build.js

@@ -17,9 +17,11 @@ const postcssUrl = require('postcss-url')
 const postcssVar = require('postcss-custom-properties')
 const { Transform } = require('stream')
 const map = (transform) => new Transform({ objectMode: true, transform })
+const replace = require('gulp-replace')
 const through = () => map((file, enc, next) => next(null, file))
 const uglify = require('gulp-uglify')
 const vfs = require('vinyl-fs')
+const git = require('git-rev-sync')
 
 module.exports = (src, dest, preview) => () => {
   const opts = { base: src, cwd: src }
@@ -101,7 +103,9 @@ module.exports = (src, dest, preview) => () => {
     vfs.src('helpers/*.js', opts),
     vfs.src('layouts/*.hbs', opts),
     vfs.src('partials/*.hbs', opts)
-  ).pipe(vfs.dest(dest, { sourcemaps: sourcemaps && '.' }))
+      .pipe(replace('@@antora-ui-version', git.isTagDirty() ? git.long() : git.tag()))
+  ).pipe(vfs.dest(dest, { sourcemaps: sourcemaps && '.' })
+  )
 }
 
 function bundle ({ base: basedir, ext: bundleExt = '.bundle.js' }) {

package.json

@@ -39,12 +39,14 @@
     "eslint-plugin-promise": "~4.2",
     "eslint-plugin-standard": "~4.0",
     "fancy-log": "~2.0",
+    "git-rev-sync": "^3.0.2",
     "gulp": "~4.0",
     "gulp-concat": "~2.6",
     "gulp-connect": "~5.7",
     "gulp-eslint": "~6.0",
     "gulp-imagemin": "~6.2",
     "gulp-postcss": "~9.0",
+    "gulp-replace": "~1.1",
     "gulp-stylelint": "~13.0",
     "gulp-uglify": "~3.0",
     "gulp-vinyl-zip": "~2.5",
@@ -69,6 +71,7 @@
   },
   "dependencies": {
     "@algolia/client-search": "^4.17.0",
-    "@primer/octicons": "^19.8.0"
+    "@primer/octicons": "^19.8.0",
+    "init": "^0.1.2"
   }
 }

src/partials/head-meta.hbs

@@ -1,4 +1,5 @@
     {{!-- Add additional meta tags here --}}
+    <meta name="antora-ui-version" content="@@antora-ui-version"> {{!-- replaced by the gulp build --}}
     <meta name="version" content="{{{page.version}}}">
     <meta name="component" content="{{{page.component.name}}}">
     <meta name="latest-version" content="{{~#if (and page.latest (eq page.url page.latest.url))}}true{{~else}}false{{~/if}}">