feat: add pluginImageRegistry and pluginImageNamespace config for built-in plugins

[johnlanni]

What this PR does

This PR adds support for customizing the plugin image registry and namespace for built-in plugins without modifying the plugins.properties file.

Changes

1. WasmPluginServiceConfig.java:

   • Added pluginImageRegistry and pluginImageNamespace fields
   • Added support for environment variables HIGRESS_ADMIN_WASM_PLUGIN_IMAGE_REGISTRY and HIGRESS_ADMIN_WASM_PLUGIN_IMAGE_NAMESPACE

2. WasmPluginServiceImpl.java:

   • Added buildPluginImageUrl() method to construct plugin image URL with custom registry/namespace
   • Priority: customPattern > registry/namespace > defaultUrl

3. helm/values.yaml:

   • Added pluginServer.imageRegistry and pluginServer.imageNamespace options
   • Added global.hub and global.pluginNamespace for parent chart integration

4. helm/templates/deployment.yaml:

   • Added environment variable injection for the new config options
   • Support fallback: pluginServer.imageRegistry → global.hub

Priority Chain

For plugin image registry:

1. pluginServer.imageRegistry (direct config)
2. global.hub (parent chart, shared with deployments)

For plugin image namespace:

1. pluginServer.imageNamespace (direct config)
2. global.pluginNamespace (parent chart)

Usage

Users can customize the plugin image registry via:

1. Helm values (from parent higress chart):

global:
  hub: my-registry.example.com  # Shared with deployments
  pluginNamespace: my-plugins   # Optional, default is "plugins"

2. Helm values (standalone or override):

pluginServer:
  imageRegistry: "my-registry.example.com"
  imageNamespace: "my-plugins"

3. Environment variables:

HIGRESS_ADMIN_WASM_PLUGIN_IMAGE_REGISTRY=my-registry.example.com
HIGRESS_ADMIN_WASM_PLUGIN_IMAGE_NAMESPACE=my-plugins

Image URL Transformation

Default URL:

oci://higress-registry.cn-hangzhou.cr.aliyuncs.com/plugins/ai-proxy:2.0.0

With global.hub=my-registry.example.com:

oci://my-registry.example.com/plugins/ai-proxy:2.0.0

Related

This PR works together with higress PR #3521 to provide a complete solution for customizing plugin image locations using a shared global.hub parameter.