Include flux git ref in info endpoint

backend/areas/__init__.py

@@ -62,14 +62,27 @@ def api_info():
             if 'version' in data:
                 results['appVersions'][app] = data['version']
 
-    # Get latest released version from gitlab.
-    git_release = requests.get("https://open.greenhost.net/stackspin/stackspin/-/raw/main/VERSION").text.rstrip()
-    results['lastRelease'] = git_release
-
     # Get last update time of stackspin GitRepo object on the cluster; that
     # tells us when flux last updated the cluster based on changes in the
     # stackspin git repo.
     stackspin_repo = k8s.get_gitrepo('stackspin')
     results['lastUpdated'] = stackspin_repo['status']['artifact']['lastUpdateTime']
 
+    # This is the branch (or other git ref, like tag or commit) that this
+    # cluster follows.
+    flux_ref = stackspin_repo['spec']['ref']
+    results['followingGit'] = {}
+    results['followingGit']['object'] = stackspin_repo['spec']['ref']
+    # The `flux_ref` is a structured object, though as far as we've seen always
+    # a dict with a single entry. (The key can be `branch` or `tag` or
+    # `commit`.) We need to reduce this to a single string git ref as well.
+    ref = next(iter(flux_ref.values()))
+    results['followingGit']['string'] = ref
+
+    # Get latest released version from gitlab. Whether it's considered
+    # "released" depends on which branch we're following, but usually that's
+    # the `vX` "production" branch.
+    git_release = requests.get(f"https://open.greenhost.net/stackspin/stackspin/-/raw/{ref}/VERSION").text.rstrip()
+    results['lastRelease'] = git_release
+
     return jsonify(results)