feat(antora-ui): BOOSTLOOK_BRANCH option

Author: alandefreitas

.github/workflows/publish.yml

@@ -78,6 +78,8 @@ jobs:
         shell: bash
         run: |
           set -x
+          BOOSTLOOK_BRANCH="${{ (startsWith(github.ref, 'refs/heads/develop') && 'develop') || 'master' }}"
+          export BOOSTLOOK_BRANCH
           ./build.sh
 
       - name: Setup Ninja

antora-ui/README.adoc

@@ -122,7 +122,8 @@ When the command completes successfully, the UI bundle will be available at `bui
 
 This project uses the Boost color scheme and typography available from `https://github.com/cppalliance/boostlook`.
 
-In the build step, the `boostlook` stylesheet is included in the bundle and used in the UI. When working on the Antora content, the `boostlook` stylesheet is updated every hour to ensure the latest version is used.
+In the build step, the `boostlook` stylesheet is included in the bundle and used in the UI.
+When working on the Antora content, the `boostlook` stylesheet is updated every hour to ensure the latest version is used.
 
 If you're working on the `boostlook.css` file and don't want the build step to include the latest version, you can use the `--skip-boostlook` to ensure the task does not attempt to fetch the latest version.
 
@@ -138,3 +139,14 @@ or in preview mode:
 gulp preview --skip-boostlook
 ----
 
+By default, the `boostlook` stylesheet is downloaded from the `master` branch of the `cppalliance/boostlook` repository.
+The `BOOSTLOOK_BRANCH` environment variable can be set to use a different branch.
+
+[source,bash]
+----
+BOOSTLOOK_BRANCH=develop
+export BOOSTLOOK_BRANCH
+gulp bundle
+----
+
+In CI, the `develop` branch is used to ensure the latest version is included in the bundle unless the current branch is `master`.

antora-ui/gulp.d/tasks/build.js

@@ -240,7 +240,8 @@ async function fetchBoostlookCss () {
   const skipBoostlook = process.argv.includes('--skip-boostlook')
   const cssDir = ospath.join(__dirname, '..', '..', 'src', 'css')
   const cssFilePath = ospath.join(cssDir, 'boostlook.css')
-  const url = 'https://raw.githubusercontent.com/boostorg/boostlook/master/boostlook.css'
+  const boostlookBranch = process.env.BOOSTLOOK_BRANCH || 'master'
+  const url = `https://raw.githubusercontent.com/cppalliance/boostlook/${boostlookBranch}/boostlook.css`
 
   if (skipBoostlook) {
     log('Skipping boostlook.css download due to --skip-boostlook flag.')