Cache serialised services in Redis

Same as we’re doing for templates.

This means avoiding a database call, even for services that don’t hit
our API so often.

They’ll still need to go to the database for the API keys, because we’re
not comfortable putting the API key secrets in Redis.

But once a service has got its keys from the database we commit the
transaction, so the connection can be freed up until we need it again to
insert the notification.

tests/app/v2/notifications/test_post_notifications.py

@@ -240,9 +240,9 @@ def test_should_cache_template_lookups_in_memory(mocker, client, sample_template
     assert Notification.query.count() == 5
 
 
-def test_should_cache_template_lookups_in_redis(mocker, client, sample_template):
+def test_should_cache_template_and_service_in_redis(mocker, client, sample_template):
 
-    from app.schemas import template_schema
+    from app.schemas import service_schema, template_schema
 
     mock_redis_get = mocker.patch(
         'app.redis_store.get',
@@ -266,34 +266,49 @@ def test_should_cache_template_lookups_in_redis(mocker, client, sample_template)
         headers=[('Content-Type', 'application/json'), auth_header]
     )
 
-    expected_key = f'template-{sample_template.id}-version-None'
+    expected_service_key = f'service-{sample_template.service_id}'
+    expected_templates_key = f'template-{sample_template.id}-version-None'
 
-    assert mock_redis_get.call_args_list == [call(
-        expected_key,
-    )]
+    assert mock_redis_get.call_args_list == [
+        call(expected_service_key),
+        call(expected_templates_key),
+    ]
 
+    service_dict = service_schema.dump(sample_template.service).data
     template_dict = template_schema.dump(sample_template).data
 
-    assert len(mock_redis_set.call_args_list) == 1
-    assert mock_redis_set.call_args[0][0] == expected_key
-    assert json.loads(mock_redis_set.call_args[0][1]) == {
-        'data': template_dict,
-    }
-    assert mock_redis_set.call_args[1]['ex'] == 604_800
+    assert len(mock_redis_set.call_args_list) == 2
+
+    service_call, templates_call = mock_redis_set.call_args_list
+
+    assert service_call[0][0] == expected_service_key
+    assert json.loads(service_call[0][1]) == {'data': service_dict}
+    assert service_call[1]['ex'] == 604_800
+
+    assert templates_call[0][0] == expected_templates_key
+    assert json.loads(templates_call[0][1]) == {'data': template_dict}
+    assert templates_call[1]['ex'] == 604_800
 
 
 def test_should_return_template_if_found_in_redis(mocker, client, sample_template):
 
-    from app.schemas import template_schema
+    from app.schemas import service_schema, template_schema
+    service_dict = service_schema.dump(sample_template.service).data
     template_dict = template_schema.dump(sample_template).data
 
     mocker.patch(
         'app.redis_store.get',
-        return_value=json.dumps({'data': template_dict}).encode('utf-8')
+        side_effect=[
+            json.dumps({'data': service_dict}).encode('utf-8'),
+            json.dumps({'data': template_dict}).encode('utf-8'),
+        ],
     )
     mock_get_template = mocker.patch(
         'app.dao.templates_dao.dao_get_template_by_id_and_service_id'
     )
+    mock_get_service = mocker.patch(
+        'app.dao.services_dao.dao_fetch_service_by_id'
+    )
 
     mocker.patch('app.celery.provider_tasks.deliver_sms.apply_async')
 
@@ -311,6 +326,7 @@ def test_should_return_template_if_found_in_redis(mocker, client, sample_templat
 
     assert response.status_code == 201
     assert mock_get_template.called is False
+    assert mock_get_service.called is False
 
 
 @pytest.mark.parametrize("notification_type, key_send_to, send_to",