fix(controller): update App.structure field correctly after scaling

While the scaling logic is correct, we were naively using the requested
scaling values to update the App.structure JSON field, rather than the
actual containers in existence after scaling. This was cosmetic only,
but is fixed by a SQL aggregate query and python dict comprehension.
Includes regression unit tests.

Author: mboersma

controller/api/models.py

@@ -18,6 +18,7 @@
 from django.contrib.auth import get_user_model
 from django.core.exceptions import ValidationError
 from django.db import models
+from django.db.models import Count
 from django.db.models import Max
 from django.db.models.signals import post_delete, post_save
 from django.dispatch import receiver
@@ -201,7 +202,8 @@ def scale(self, user, structure):  # noqa
             if to_remove:
                 self._destroy_containers(to_remove)
         # save new structure to the database
-        self.structure = structure
+        vals = self.container_set.values('type').annotate(Count('pk')).order_by()
+        self.structure = {v['type']: v['pk__count'] for v in vals}
         self.save()
         return changed
 

controller/api/tests/test_container.py

@@ -107,7 +107,12 @@ def test_container_api_heroku(self):
         self.assertEqual(response.status_code, 201)
         # scale up
         url = "/v1/apps/{app_id}/scale".format(**locals())
-        body = {'web': 4, 'worker': 2}
+        # test setting one proc type at a time
+        body = {'web': 4}
+        response = self.client.post(url, json.dumps(body), content_type='application/json',
+                                    HTTP_AUTHORIZATION='token {}'.format(self.token))
+        self.assertEqual(response.status_code, 204)
+        body = {'worker': 2}
         response = self.client.post(url, json.dumps(body), content_type='application/json',
                                     HTTP_AUTHORIZATION='token {}'.format(self.token))
         self.assertEqual(response.status_code, 204)
@@ -118,6 +123,9 @@ def test_container_api_heroku(self):
         url = "/v1/apps/{app_id}".format(**locals())
         response = self.client.get(url, HTTP_AUTHORIZATION='token {}'.format(self.token))
         self.assertEqual(response.status_code, 200)
+        # ensure the structure field is up-to-date
+        self.assertEqual(response.data['structure']['web'], 4)
+        self.assertEqual(response.data['structure']['worker'], 2)
         # test listing/retrieving container info
         url = "/v1/apps/{app_id}/containers/web".format(**locals())
         response = self.client.get(url, HTTP_AUTHORIZATION='token {}'.format(self.token))
@@ -130,6 +138,7 @@ def test_container_api_heroku(self):
         self.assertEqual(response.data['num'], num)
         # scale down
         url = "/v1/apps/{app_id}/scale".format(**locals())
+        # test setting two proc types at a time
         body = {'web': 2, 'worker': 1}
         response = self.client.post(url, json.dumps(body), content_type='application/json',
                                     HTTP_AUTHORIZATION='token {}'.format(self.token))
@@ -142,6 +151,9 @@ def test_container_api_heroku(self):
         url = "/v1/apps/{app_id}".format(**locals())
         response = self.client.get(url, HTTP_AUTHORIZATION='token {}'.format(self.token))
         self.assertEqual(response.status_code, 200)
+        # ensure the structure field is up-to-date
+        self.assertEqual(response.data['structure']['web'], 2)
+        self.assertEqual(response.data['structure']['worker'], 1)
         # scale down to 0
         url = "/v1/apps/{app_id}/scale".format(**locals())
         body = {'web': 0, 'worker': 0}