Merge pull request #671 from cderici/get-series-from-app-instead-of-metadata

[JUJU-981] Get series from deployed app instead of metadata when charm upgrade

#### Description

Charmhub is modeling the charm data separately from where the charm is deployed, therefore the series is not a part of the metadata anymore. So instead of getting the series from the metadata we now get it from the deployed application first, then we try the model config, if everything fails then we look at the metadata as a last resort (mostly to keep backwards ompatibility).

Fixes #668 

#### QA Steps

The charm used for the integration test `test_upgrade_local_charm` has been updated to simulate what's happening in #668 (now it has multiple series where the first one is not the one that the charm was initially deployed on), so along with the rest of the CI tests, the following should pass with this change (which fails without the change):

```sh
tox -e integration -- tests/integration/test_application.py::test_upgrade_local_charm
```

#### Notes & Discussion

I initially thought that this would be a breaking change (needs a version bump), however, we're still keeping the old way of getting the series in case the new ways fail, so this shouldn't break anything.

Author: jameinel

juju/application.py

@@ -339,6 +339,18 @@ async def unexpose(self, exposed_endpoints=None):
         log.debug("Unexposing %s", self.name)
         return await app_facade.Unexpose(application=self.name)
 
+    async def get_series(self):
+        """Return the series on which the application is deployed
+
+        :return: str series
+        """
+        app_facade = self._facade()
+
+        log.debug(
+            'Getting series for %s', self.name)
+
+        return (await app_facade.Get(application=self.name)).series
+
     async def get_config(self):
         """Return the configuration settings dict for this application.
         """
@@ -728,9 +740,12 @@ async def local_refresh(
         charm_dir = path.expanduser().resolve()
         model_config = await self.get_config()
 
-        series = await get_charm_series(charm_dir, self.model)
+        series = (
+            await self.get_series() or
+            self.model.info.get('default-series', '') or
+            await get_charm_series(charm_dir, self.model)
+        )
         if not series:
-            model_config = await self.get_config()
             default_series = model_config.get("default-series")
             if default_series:
                 series = default_series.value

tests/charm-folder-symlink/metadata.yaml

@@ -1,7 +1,4 @@
 name: simple
 summary: A simple example charm with the new operator framework
 description: |
-    Simple is an example charm
-series:
-- xenial
-- bionic
+    Simple is an example charm

tests/integration/bundle/cmr-bundle.yaml

@@ -1,12 +1,11 @@
-series: bionic
 saas:
-  mysql:
-    url: admin/{}.mysql
+  influxdb:
+    url: admin/{}.influxdb
 applications:
-  wordpress:
-    charm: wordpress
+  grafana:
+    charm: grafana
     channel: stable
     num_units: 1
 relations:
-- - wordpress:db
-  - mysql:db
+- - grafana:grafana-source
+  - influxdb:grafana-source

tests/integration/test_crossmodel.py

@@ -165,20 +165,19 @@ async def test_add_bundle(event_loop):
                 raise
 
             await model_1.deploy(
-                'mysql',
-                application_name='mysql',
-                series='xenial',
+                'influxdb',
+                application_name='influxdb',
                 channel='stable',
             )
-            assert 'mysql' in model_1.applications
+            assert 'influxdb' in model_1.applications
             await model_1.wait_for_idle(status="active")
 
-            await model_1.create_offer("mysql:db")
+            await model_1.create_offer("influxdb:grafana-source")
 
             offers = await model_1.list_offers()
 
             await model_1.block_until(
-                lambda: all(offer.application_name == 'mysql'
+                lambda: all(offer.application_name == 'influxdb'
                             for offer in offers.results),
                 timeout=60 * wait_for_min)
 
@@ -187,4 +186,4 @@ async def test_add_bundle(event_loop):
                 await model_2.deploy('local:{}'.format(tmp_path))
                 await model_2.wait_for_idle(status="active")
 
-            await model_1.remove_offer("admin/{}.mysql".format(model_1.info.name), force=True)
+            await model_1.remove_offer("admin/{}.influxdb".format(model_1.info.name), force=True)

tests/integration/upgrade-charm/metadata.yaml

@@ -1,5 +1,5 @@
 name: ubuntu
-series: ["focal"]
+series: ["bionic", "focal"]
 summary: "test"
 description: "test"
 maintainers: ["test"]