cockpit: Add clients and backup manifests

- Clients information allows us to show launch web interface button consistently
  like other applications instead of showing it in the description.

- Empty backup information allows for the application to be installed when a
  backup is restored.

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/cockpit/__init__.py

@@ -28,6 +28,8 @@ from plinth.modules import names
 from plinth.signals import domain_added, domain_removed, domainname_change
 from plinth.utils import format_lazy
 
+from .manifest import backup, clients
+
 version = 1
 
 managed_services = ['cockpit.socket']

plinth/modules/cockpit/manifest.py

@@ -0,0 +1,38 @@
+#
+# This file is part of FreedomBox.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# 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/>.
+#
+"""
+Application manifest for cockpit.
+"""
+
+from django.utils.translation import ugettext_lazy as _
+
+from plinth.modules.backups.api import validate as validate_backup
+from plinth.clients import validate
+
+clients = validate([{
+    'name': _('Cockpit'),
+    'platforms': [{
+        'type': 'web',
+        'url': '/_cockpit/'
+    }]
+}])
+
+# cockpit.conf need not be backed up because add/remove domain signals are
+# triggered on every Plinth domain change (and cockpit application install) and
+# will set the value of allowed domains correctly. This is the only key the is
+# customized in cockpit.conf.
+backup = validate_backup({})

plinth/modules/cockpit/urls.py

@@ -29,6 +29,7 @@ urlpatterns = [
             service_id=cockpit.managed_services[0],
             diagnostics_module_name='cockpit',
             description=cockpit.description,
-            show_status_block=True),
+            show_status_block=True,
+            clients=cockpit.clients),
         name='index'),
 ]