packages: Button to refresh package lists

- This is a fallback solution to manually refresh package lists on AWS images
  since they come with no apt package lists.
- This can also be occasionally useful for people running the testing
  distribution where packages might be frequently added and removed.

Signed-off-by: Joseph Nuthalapati <njoseph@thoughtworks.com>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/package.py

@@ -14,18 +14,17 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
-
 """
 Framework for installing and updating distribution packages
 """
 
-from django.utils.translation import ugettext as _
 import logging
 import subprocess
 import threading
 
-from plinth import actions
+from django.utils.translation import ugettext as _
 
+from plinth import actions
 
 logger = logging.getLogger(__name__)
 
@@ -90,6 +89,14 @@ class Transaction(object):
             logger.exception('Error installing package: %s', exception)
             raise
 
+    def refresh_package_lists(self):
+        """Refresh apt package lists."""
+        try:
+            self._run_apt_command(['update'])
+        except subprocess.CalledProcessError as exception:
+            logger.exception('Error updating package lists: %s', exception)
+            raise
+
     def _run_apt_command(self, arguments):
         """Run apt-get and update progress."""
         self._reset_status()
@@ -151,3 +158,9 @@ def is_package_manager_busy():
         return True
     except actions.ActionError:
         return False
+
+
+def refresh_package_lists():
+    """To be run in case apt package lists are outdated."""
+    transaction = Transaction(None, None)
+    transaction.refresh_package_lists()

plinth/templates/setup.html

@@ -77,10 +77,13 @@
           {% blocktrans trimmed %}
             This application is currently not available in your distribution.
           {% endblocktrans %}
+          <button type="submit" class="btn btn-default btn-sm" name="refresh-packages">
+            <span class="glyphicon glyphicon-refresh"></span> Check again
+          </button>
         </div>
       {% endif %}
 
-      <input type="submit" class="btn btn-md btn-primary"
+      <input type="submit" class="btn btn-md btn-primary" name="install"
              {% if package_manager_is_busy or setup_helper.has_unavailable_packages %}
              disabled="disabled"
              {% endif %}
@@ -92,6 +95,7 @@
 
     </form>
 
+
   {% else %}
 
     {% if setup_helper.current_operation.step == 'pre' %}

plinth/views.py

@@ -181,16 +181,22 @@ class SetupView(TemplateView):
         context['package_manager_is_busy'] = package.is_package_manager_busy()
         return context
 
-    def post(self, *args, **kwargs):
-        """Handle installing/upgrading applications.
+    def dispatch(self, request, *args, **kwargs):
+        if request.method == 'POST':
+            if 'install' in request.POST:
+                # Handle installing/upgrading applications.
+                # Start the application setup, and refresh the page every few
+                # seconds to keep displaying the status.
+                self.kwargs['setup_helper'].run_in_thread()
 
-        Start the application setup, and refresh the page every few
-        seconds to keep displaying the status.
-        """
-        self.kwargs['setup_helper'].run_in_thread()
+                # Give a moment for the setup process to start and show
+                # meaningful status.
+                time.sleep(1)
+                return self.render_to_response(self.get_context_data())
 
-        # Give a moment for the setup process to start and show
-        # meaningful status.
-        time.sleep(1)
-
-        return self.render_to_response(self.get_context_data())
+            elif 'refresh-packages' in request.POST:
+                # Refresh apt package lists
+                package.refresh_package_lists()
+                return self.render_to_response(self.get_context_data())
+        else:
+            return super(SetupView, self).dispatch(request, *args, **kwargs)