feat: istio-pilot configurable images

#322

Summary of changes:
- Added unit tests.
- Modified config.yaml to make it consistent.
- Added get config helper to allow for better testing. This can also be
  expanded further.

charms/istio-pilot/config.yaml

@@ -1,20 +1,20 @@
 options:
-  image_configuration:
+  default-gateway:
+    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'
+      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
-  default-gateway:
-    type: string
-    default: istio-gateway
-    description: Name to use as a default gateway
   gateway-service-name:
     type: string
     default: istio-ingressgateway-workload

charms/istio-pilot/src/charm.py

@@ -2,11 +2,10 @@
 
 import logging
 import subprocess
-import yaml
-from pathlib import Path
 from typing import List, Optional
 
 import tenacity
+import yaml
 from charmed_kubeflow_chisme.exceptions import ErrorWithStatus, GenericCharmRuntimeError
 from charmed_kubeflow_chisme.kubernetes import (
     KubernetesResourceHandler,
@@ -19,7 +18,6 @@
 )
 from charms.istio_pilot.v0.istio_gateway_info import GatewayProvider
 from charms.prometheus_k8s.v0.prometheus_scrape import MetricsEndpointProvider
-from jinja2 import Template
 from lightkube import Client
 from lightkube.core.exceptions import ApiError
 from lightkube.generic_resource import create_namespaced_resource
@@ -56,7 +54,7 @@
 }
 GATEWAY_TEMPLATE_FILES = ["src/manifests/gateway.yaml.j2"]
 DEFAULT_IMAGES = {}
-IMAGE_CONFIGURATION = "image_configuration"
+IMAGE_CONFIGURATION = "image-configuration"
 KRH_GATEWAY_SCOPE = "gateway"
 METRICS_PORT = 15014
 INGRESS_AUTH_RELATION_NAME = "ingress-auth"
@@ -160,18 +158,24 @@ 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 install(self, _):
         """Install charm."""
         self._log_and_set_status(MaintenanceStatus("Deploying Istio control plane"))
 
-        image_configuration = yaml.safe_load(self.model.config[IMAGE_CONFIGURATION])
-        pilot_image = image_configuration["pilot_image"]
-        global_tag = image_configuration["global_tag"]
-        global_hub= image_configuration["global_hub"]
-        global_proxy_image = image_configuration["global_proxy_image"]
-        global_proxy_init_image = image_configuration["global_proxy_init_image"]
+        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"]
 
-        # Call istioctl install and set paramters based on image configuratiob
+        # Call istioctl install and set parameters based on image configuration
         subprocess.check_call(
             [
                 "./istioctl",
@@ -182,15 +186,15 @@ def install(self, _):
                 "--set",
                 "values.global.istioNamespace=kubeflow",
                 "--set",
-                f"values.pilot.image='{pilot_image}'",
+                f"values.pilot.image={pilot_image}",
                 "--set",
-                f"values.global.tag='{global_tag}'",
+                f"values.global.tag={global_tag}",
                 "--set",
-                f"values.global.hub='{global_hub}'",
+                f"values.global.hub={global_hub}",
                 "--set",
-                f"values.global.proxy.image='{global_proxy_image}'",
+                f"values.global.proxy.image={global_proxy_image}",
                 "--set",
-                f"values.global.proxy_init.image='{global_proxy_init_image}'",
+                f"values.global.proxy_init.image={global_proxy_init_image}",
             ]
         )
 
@@ -838,6 +842,7 @@ def _remove_envoyfilter(name: str, namespace: str, logger: Optional[logging.Logg
             return
         raise e
 
+
 def _validate_upgrade_version(versions) -> bool:
     """Validates that the version of istioctl can upgrade the currently deployed Istio.
 

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

@@ -1039,6 +1039,15 @@ 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()
+        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"]
+
 
 class TestCharmUpgrade:
     """Tests for charm upgrade handling."""