Kf 3996 istio-pilot control plane configurable images with set (#321)

# Description
More details in: #322
The changes in this PR are based on work done in #316
Created a new PR to simplify workflow.

# Summary of changes:
- Modified code to use --set to alter precompile istioctl manifests to allow changes according to charm configuration.
- Added `image-configuration` option to istio-pilot `config.yaml`
- Added `proxy-image` option to istio-gatewat `config.yaml`
- Added unit test for testing helper that retrieves configuration.

# Testing

For complete testing refer to #322

Related PR: #320

NOTE: Created [issue](#324) to track updates to process of updating Istio.

charms/istio-pilot/config.yaml

@@ -3,6 +3,18 @@ options:
     type: string
     default: istio-gateway
     description: Name to use as a default gateway
+  image-configuration:
+    default: |
+      pilot-image: 'pilot'  # values.pilot.image
+      global-tag: '1.17.3'  # values.global.tag
+      global-hub: 'docker.io/istio' # values.global.hub
+      global-proxy-image: 'proxyv2' # values.global.proxy.image
+      global-proxy-init-image: 'proxyv2' # values.global.proxy_init.image
+      grpc-bootstrap-init: 'busybox:1.28'
+    description: >
+      YAML or JSON formatted input defining image configuration to use when installing the Istio control plane.
+      For reference https://istio.io/v1.5/docs/reference/config/installation-options/
+    type: string
   gateway-service-name:
     type: string
     default: istio-ingressgateway-workload

charms/istio-pilot/src/charm.py

@@ -5,6 +5,7 @@
 from typing import List, Optional
 
 import tenacity
+import yaml
 from charmed_kubeflow_chisme.exceptions import ErrorWithStatus, GenericCharmRuntimeError
 from charmed_kubeflow_chisme.kubernetes import (
     KubernetesResourceHandler,
@@ -52,6 +53,7 @@
     "https": 8443,
 }
 GATEWAY_TEMPLATE_FILES = ["src/manifests/gateway.yaml.j2"]
+IMAGE_CONFIGURATION = "image-configuration"
 KRH_GATEWAY_SCOPE = "gateway"
 METRICS_PORT = 15014
 INGRESS_AUTH_RELATION_NAME = "ingress-auth"
@@ -155,19 +157,42 @@ def __init__(self, *args):
         )
         self.grafana_dashboards = GrafanaDashboardProvider(self, relation_name="grafana-dashboard")
 
+    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"))
 
+        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(
             [
                 "./istioctl",
                 "install",
                 "-y",
-                "-s",
+                "--set",
                 "profile=minimal",
-                "-s",
-                f"values.global.istioNamespace={self.model.name}",
+                "--set",
+                "values.global.istioNamespace=kubeflow",
+                "--set",
+                f"values.pilot.image={pilot_image}",
+                "--set",
+                f"values.global.tag={global_tag}",
+                "--set",
+                f"values.global.hub={global_hub}",
+                "--set",
+                f"values.global.proxy.image={global_proxy_image}",
+                "--set",
+                f"values.global.proxy_init.image={global_proxy_init_image}",
             ]
         )
 

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

@@ -1039,6 +1039,14 @@ def test_xor(self, left, right, expected):
         """Test that the xor helper function works as expected."""
         assert _xor(left, right) is expected
 
+    def test_get_config(self, harness):
+        """Test configuration retrieval function."""
+        harness.begin()
+        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:
     """Tests for charm upgrade handling."""