fix: updated according to code review

Summary of changes:
- Modified code to only retrieve image configuration.

charms/istio-pilot/src/charm.py

@@ -157,22 +157,21 @@ def __init__(self, *args):
         )
         self.grafana_dashboards = GrafanaDashboardProvider(self, relation_name="grafana-dashboard")
 
-    def _get_config(self):
-        """Retrieve and return configuration."""
-        config = {}
-        config[IMAGE_CONFIGURATION] = yaml.safe_load(self.model.config[IMAGE_CONFIGURATION])
-        return config
+    def _get_image_config(self):
+        """Retrieve and return image configuration."""
+        image_config = yaml.safe_load(self.model.config[IMAGE_CONFIGURATION])
+        return image_config
 
     def install(self, _):
         """Install charm."""
         self._log_and_set_status(MaintenanceStatus("Deploying Istio control plane"))
 
-        config = self._get_config()
-        pilot_image = config[IMAGE_CONFIGURATION]["pilot-image"]
-        global_tag = config[IMAGE_CONFIGURATION]["global-tag"]
-        global_hub = config[IMAGE_CONFIGURATION]["global-hub"]
-        global_proxy_image = config[IMAGE_CONFIGURATION]["global-proxy-image"]
-        global_proxy_init_image = config[IMAGE_CONFIGURATION]["global-proxy-init-image"]
+        image_config = self._get_image_config()
+        pilot_image = image_config["pilot-image"]
+        global_tag = image_config["global-tag"]
+        global_hub = image_config["global-hub"]
+        global_proxy_image = image_config["global-proxy-image"]
+        global_proxy_init_image = image_config["global-proxy-init-image"]
 
         # Call istioctl install and set parameters based on image configuration
         subprocess.check_call(

charms/istio-pilot/tests/unit/test_charm.py

@@ -1042,11 +1042,10 @@ def test_xor(self, left, right, expected):
     def test_get_config(self, harness):
         """Test configuration retrieval function."""
         harness.begin()
-        config = harness.charm._get_config()
-        assert "image-configuration" in config.keys()
-        assert "pilot-image" in config["image-configuration"].keys()
-        assert "pilot" == config["image-configuration"]["pilot-image"]
-        assert "proxyv2" == config["image-configuration"]["global-proxy-image"]
+        image_config = harness.charm._get_image_config()
+        assert "pilot-image" in image_config.keys()
+        assert "pilot" == image_config["pilot-image"]
+        assert "proxyv2" == image_config["global-proxy-image"]
 
 
 class TestCharmUpgrade: