views: Implement an API to retrieve the readiness status in JSON

- This can have may uses such as:

  - Waiting properly on the reboot page until the system has been restarted
  while showing the status.

  - Or, waiting for first setup to complete before running functional tests.

  - Or, monitoring for the health status of FreedomBox in general.

- The page is public as all the information conveyed there is also already
public. Should we introduce any sensitive information there such as
'operations_in_progress', we can provide that information only to
administrators.

Tests:

- Visiting /plinth/status/ shows the status in JSON. Using curl to retrieve the
information is also possible.

- During the first setup 'is_first_setup_running' is 'true'. After it has
completed, it is 'false'.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Veiko Aasa <veiko17@disroot.org>

plinth/modules/first_boot/middleware.py

@@ -30,9 +30,10 @@ class FirstBootMiddleware(MiddlewareMixin):
         if user_requests_login:
             return
 
-        # Don't interfere with help pages
+        # Don't interfere with help or status pages
         user_requests_help = request.path.startswith(reverse('help:index'))
-        if user_requests_help:
+        user_requests_status = request.path.startswith(reverse('status'))
+        if user_requests_help or user_requests_status:
             return
 
         # Don't interfere with first setup progress page. When first setup is

plinth/urls.py

@@ -18,6 +18,7 @@ system_urlpatterns = [
 
 urlpatterns = [
     re_path(r'^$', views.index, name='index'),
+    re_path(r'^status/$', views.status, name='status'),
     re_path(r'^language-selection/$',
             public(views.LanguageSelectionView.as_view()),
             name='language-selection'),

plinth/views.py

@@ -178,6 +178,16 @@ def index(request):
         })
 
 
+@public
+def status(request):
+    """Return the status of service in JSON format."""
+    status = {
+        'is_available': True,
+        'is_first_setup_running': setup.is_first_setup_running
+    }
+    return JsonResponse(status)
+
+
 def _pick_menu_items(menu_items, selected_tags):
     """Return a sorted list of menu items filtered by tags."""