Merge ~mthaddon/charm-k8s-gunicorn/+git/charm-k8s-gunicorn:image-resource into charm-k8s-gunicorn:master

[Tom Haddon]

Switch the charm to use OCI Resource for image

Switch the charm to use OCI Resource for image.

We're in the process of converting this charm to the new sidecar/pebble approach. Making these changes now will lessen the diff to the main repo when we're ready to merge.

[🤖 prod-jenkaas-is (prod-jenkaas-is)]

A CI job is currently in progress. A follow up comment will be added when it completes.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[🤖 prod-jenkaas-is (prod-jenkaas-is)]

FAILED: Continuous integration, rev:5bb4bdfbc895a31f459f9c5ec42cd014aeee73cc
https://jenkins.canonical.com/is/job/lp-charm-k8s-gunicorn-ci/5/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/is/job/lp-charm-test/46/
    None: https://jenkins.canonical.com/is/job/lp-update-mp/59496/

Click here to trigger a rebuild:
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review: Needs Fixing (continuous-integration)

[🤖 prod-jenkaas-is (prod-jenkaas-is)]

PASSED: Continuous integration, rev:5bb4bdfbc895a31f459f9c5ec42cd014aeee73cc
https://jenkins.canonical.com/is/job/lp-charm-k8s-gunicorn-ci/6/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/is/job/lp-charm-test/47/
    None: https://jenkins.canonical.com/is/job/lp-update-mp/59534/

Click here to trigger a rebuild:
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review: Approve (continuous-integration)

[Stuart Bishop (stub)]

This all looks fine. I expect this will need a further revision when Operator Framework supports OCI image resources properly, so this change may be premature in that way. But overall it seems a good idea as it means the deployment documentation will remain consistent for Juju 2.9.

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision d030817c6f41df25bf6fb9f412a0104e23395ccf

diff --git a/README.md b/README.md
index fbbd51a..710b241 100644
--- a/README.md
+++ b/README.md
@@ -6,8 +6,12 @@ A charm that allows you to deploy your gunicorn application in kubernetes.
 
 ## Usage
 
+By default, the charm will deploy a simple docker image that contains a
+gunicorn app that displays a short message and its environment variables. The
+image is built using an OCI Recipe on Launchpad and published to dockerhub
+[here](https://hub.docker.com/r/gunicorncharmers/gunicorn-app).
 ```
-juju deploy cs:~gunicorn-charmers/gunicorn my-awesome-app --config image_path=localhost:32000/myapp --config external_hostname=my-awesome-app.com
+juju deploy cs:~gunicorn-charmers/gunicorn my-awesome-app
 ```
 
 ### Scale Out Usage
@@ -21,7 +25,9 @@ juju add-unit my-awesome-app
 ### Using your own image
 
 You can, of course, supply our own OCI image. gunicorn is expected to listen on
-port 80.
+port 80. To do so, specify `--resource gunicorn-image='image-location'` at
+deploy time, or use `juju attach-resource` if you want to switch images after
+initial deployment.
 
 ### Using gunicorn-base to build an image
 
@@ -45,7 +51,7 @@ added to the environment of your pods.
 The context used to render the Jinja2 template is constructed from relation
 data. For example, if you're relating with influxdb, you could do the following :
 ```
-juju deploy cs:~gunicorn-charmers/gunicorn my-awesome-app --config image_path=localhost:32000/myapp --config external_hostname=my-awesome-app.com
+juju deploy cs:~gunicorn-charmers/gunicorn my-awesome-app
 juju config my-awesome-app environment="INFLUXDB_HOST: {{influxdb.hostname}}"
 ```
 
diff --git a/config.yaml b/config.yaml
index 0754ab4..7276c75 100644
--- a/config.yaml
+++ b/config.yaml
@@ -1,21 +1,4 @@
 options:
-  image_path:
-    type: string
-    description: >
-      The location of the image to use, e.g. "registry.example.com/my_gunicorn_app:v1".
-
-      This setting is required.
-    default: ''
-  image_username:
-    type: string
-    description: >
-      The username for accessing the registry specified in image_path.
-    default: ''
-  image_password:
-    type: string
-    description: >
-      The password associated with image_username for accessing the registry specified in image_path.
-    default: ''
   environment:
     type: string
     description: >
@@ -31,5 +14,5 @@ options:
   external_hostname:
     type: string
     description: >
-      External hostname this gunicorn app should respond to.
-    default: ''
+      External hostname this gunicorn app should respond to (required).
+    default: 'foo.internal'
diff --git a/metadata.yaml b/metadata.yaml
index 4e6d497..b1a1aa7 100644
--- a/metadata.yaml
+++ b/metadata.yaml
@@ -7,6 +7,12 @@ summary: |
   Gunicorn charm
 series: [kubernetes]
 min-juju-version: 2.8.0  # charm storage in state
+resources:
+  gunicorn-image:
+    type: oci-image
+    description: docker image for Gunicorn
+    auto-fetch: true
+    upstream-source: 'gunicorncharmers/gunicorn-app:20.0.4-20.04_edge'
 requires:
   pg:
     interface: pgsql
diff --git a/requirements.txt b/requirements.txt
index fd6adcd..6b14e66 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,3 @@
 ops
 ops-lib-pgsql
+https://github.com/juju-solutions/resource-oci-image/archive/master.zip
diff --git a/src/charm.py b/src/charm.py
index 3772ef0..c25df78 100755
--- a/src/charm.py
+++ b/src/charm.py
@@ -7,6 +7,7 @@ import logging
 import yaml
 
 import ops
+from oci_image import OCIImageResource, OCIImageResourceError
 from ops.framework import StoredState
 from ops.charm import CharmBase
 from ops.main import main
@@ -20,7 +21,7 @@ import pgsql
 
 logger = logging.getLogger(__name__)
 
-REQUIRED_JUJU_CONFIG = ['image_path', 'external_hostname']
+REQUIRED_JUJU_CONFIG = ['external_hostname']
 JUJU_CONFIG_YAML_DICT_ITEMS = ['environment']
 
 
@@ -42,6 +43,8 @@ class GunicornK8sCharm(CharmBase):
     def __init__(self, *args):
         super().__init__(*args)
 
+        self.image = OCIImageResource(self, 'gunicorn-image')
+
         self.framework.observe(self.on.start, self._configure_pod)
         self.framework.observe(self.on.config_changed, self._configure_pod)
         self.framework.observe(self.on.leader_elected, self._configure_pod)
@@ -259,12 +262,14 @@ class GunicornK8sCharm(CharmBase):
         :returns: A pod spec
         """
 
-        config = self.model.config
-        image_details = {
-            'imagePath': config['image_path'],
-        }
-        if config.get('image_username', None):
-            image_details.update({'username': config['image_username'], 'password': config['image_password']})
+        try:
+            image_details = self.image.fetch()
+            logging.info("using imageDetails: {}")
+        except OCIImageResourceError:
+            logging.exception('An error occurred while fetching the image info')
+            self.unit.status = BlockedStatus('Error fetching image information')
+            return {}
+
         pod_env = self._make_pod_env()
 
         return {
diff --git a/tests/unit/scenario.py b/tests/unit/scenario.py
index f71494f..3402589 100644
--- a/tests/unit/scenario.py
+++ b/tests/unit/scenario.py
@@ -35,34 +35,23 @@ TEST_PG_CONNSTR = 'dbname=gunicorn host=1.2.3.4 password=pwd port=5432 user=usr'
 TEST_JUJU_CONFIG = {
     'defaults': {
         'config': {},
-        'logger': [
-            "ERROR:charm:Required Juju config item not set : image_path",
-            'ERROR:charm:Required Juju config item not set : external_hostname',
-        ],
-        'expected': 'Required Juju config item(s) not set : external_hostname, image_path',
-    },
-    'missing_image_path': {
-        'config': {
-            'external_hostname': 'example.com',
-        },
-        'logger': ["ERROR:charm:Required Juju config item not set : image_path"],
-        'expected': 'Required Juju config item(s) not set : image_path',
+        'logger': [],
+        'expected': False,
     },
     'missing_external_hostname': {
         'config': {
-            'image_path': 'my_gunicorn_app:devel',
+            'external_hostname': '',
         },
         'logger': ["ERROR:charm:Required Juju config item not set : external_hostname"],
         'expected': 'Required Juju config item(s) not set : external_hostname',
     },
     'good_config_no_env': {
-        'config': {'image_path': 'my_gunicorn_app:devel', 'external_hostname': 'example.com'},
+        'config': {'external_hostname': 'example.com'},
         'logger': [],
         'expected': False,
     },
     'good_config_with_env': {
         'config': {
-            'image_path': 'my_gunicorn_app:devel',
             'environment': 'MYENV: foo',
             'external_hostname': 'example.com',
         },
@@ -72,16 +61,8 @@ TEST_JUJU_CONFIG = {
 }
 
 TEST_CONFIGURE_POD = {
-    'bad_config': {
-        'config': {
-            'external_hostname': 'example.com',
-        },
-        '_leader_get': "5:\n  database: gunicorn\n  extensions: ''\n  roles: ''",
-        'expected': 'Required Juju config item(s) not set : image_path',
-    },
     'good_config_no_env': {
         'config': {
-            'image_path': 'my_gunicorn_app:devel',
             'external_hostname': 'example.com',
         },
         '_leader_get': "5:\n  database: gunicorn\n  extensions: ''\n  roles: ''",
@@ -89,7 +70,6 @@ TEST_CONFIGURE_POD = {
     },
     'good_config_with_env': {
         'config': {
-            'image_path': 'my_gunicorn_app:devel',
             'external_hostname': 'example.com',
             'environment': 'MYENV: foo',
         },
@@ -101,7 +81,6 @@ TEST_CONFIGURE_POD = {
 TEST_MAKE_POD_SPEC = {
     'basic_no_env': {
         'config': {
-            'image_path': 'my_gunicorn_app:devel',
             'external_hostname': 'example.com',
         },
         'pod_spec': {
@@ -110,7 +89,9 @@ TEST_MAKE_POD_SPEC = {
                 {
                     'name': 'gunicorn',
                     'imageDetails': {
-                        'imagePath': 'my_gunicorn_app:devel',
+                        'imagePath': 'registrypath',
+                        'password': 'password',
+                        'username': 'username',
                     },
                     'imagePullPolicy': 'Always',
                     'ports': [{'containerPort': 80, 'protocol': 'TCP'}],
@@ -122,7 +103,6 @@ TEST_MAKE_POD_SPEC = {
     },
     'basic_with_env': {
         'config': {
-            'image_path': 'my_gunicorn_app:devel',
             'external_hostname': 'example.com',
             'environment': 'MYENV: foo',
         },
@@ -132,7 +112,9 @@ TEST_MAKE_POD_SPEC = {
                 {
                     'name': 'gunicorn',
                     'imageDetails': {
-                        'imagePath': 'my_gunicorn_app:devel',
+                        'imagePath': 'registrypath',
+                        'password': 'password',
+                        'username': 'username',
                     },
                     'imagePullPolicy': 'Always',
                     'ports': [{'containerPort': 80, 'protocol': 'TCP'}],
@@ -142,38 +124,12 @@ TEST_MAKE_POD_SPEC = {
             ],
         },
     },
-    'private_registry': {
-        'config': {
-            'image_path': 'my_gunicorn_app:devel',
-            'image_username': 'foo',
-            'image_password': 'bar',
-            'external_hostname': 'example.com',
-        },
-        'pod_spec': {
-            'version': 3,  # otherwise resources are ignored
-            'containers': [
-                {
-                    'name': 'gunicorn',
-                    'imageDetails': {
-                        'imagePath': 'my_gunicorn_app:devel',
-                        'username': 'foo',
-                        'password': 'bar',
-                    },
-                    'imagePullPolicy': 'Always',
-                    'ports': [{'containerPort': 80, 'protocol': 'TCP'}],
-                    'envConfig': {},
-                    'kubernetes': {'readinessProbe': {'httpGet': {'path': '/', 'port': 80}}},
-                }
-            ],
-        },
-    },
 }
 
 
 TEST_MAKE_K8S_INGRESS = {
     'basic': {
         'config': {
-            'image_path': 'my_gunicorn_app:devel',
             'external_hostname': 'example.com',
         },
         'expected': [
diff --git a/tests/unit/test_charm.py b/tests/unit/test_charm.py
index 746dbd3..b5e1f87 100755
--- a/tests/unit/test_charm.py
+++ b/tests/unit/test_charm.py
@@ -34,6 +34,7 @@ class TestGunicornK8sCharm(unittest.TestCase):
         """Setup the harness object."""
         self.harness = testing.Harness(GunicornK8sCharm)
         self.harness.begin()
+        self.harness.add_oci_resource('gunicorn-image')
 
     def tearDown(self):
         """Cleanup the harness."""