Allow to reuse KM service Builder and config extensions (#901)

Allow to reuse KM configuration utilities in other apps.

* `IConfigurationBuilder.AddKernelMemoryConfigurationSources(...)`: adds
to .NET ConfigurationBuilder the sources used by KM service, such as
`appsettings.json`, `appsettings.<ENV>.json` (not case sensitive), user
secrets and env vars. Extension available in
[Microsoft.KernelMemory.Core](https://www.nuget.org/packages/Microsoft.KernelMemory.Core)
nuget.
* `IKernelMemoryBuilder.ConfigureDependencies(...)`: configures and
wires up all .NET dependencies accordingly to the given configuration.
Extension available in
[Microsoft.KernelMemory](https://www.nuget.org/packages/Microsoft.KernelMemory)
nuget.

extensions/KM/KernelMemory/KernelMemoryBuilderExtensions.cs

@@ -0,0 +1,49 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.Extensions.Configuration;
+using Microsoft.KernelMemory.Internals;
+
+// ReSharper disable once CheckNamespace - reduce number of "using" statements
+namespace Microsoft.KernelMemory;
+
+/// <summary>
+/// Kernel Memory builder extensions for ASP.NET apps using settings in appsettings.json
+/// and using IConfiguration. The following methods allow to fully configure KM via
+/// IConfiguration, without having to change the code using KernelMemoryBuilder and recompile.
+/// </summary>
+public static partial class KernelMemoryBuilderExtensions
+{
+    /// <summary>
+    /// Configure the builder using settings from the given IConfiguration instance.
+    /// </summary>
+    /// <param name="builder">KernelMemory builder instance</param>
+    /// <param name="appSettings">App settings, which might include KM settings</param>
+    /// <param name="memoryConfig">Optional KM settings, overriding those in appsettings</param>
+    public static IKernelMemoryBuilder ConfigureDependencies(
+        this IKernelMemoryBuilder builder,
+        IConfiguration appSettings,
+        KernelMemoryConfig? memoryConfig = null)
+    {
+        if (appSettings is null)
+        {
+            throw new ConfigurationException("The given app settings configuration is NULL");
+        }
+
+        if (memoryConfig is null)
+        {
+            memoryConfig = appSettings.GetSection(KernelMemoryComposer.ConfigRoot).Get<KernelMemoryConfig>();
+        }
+
+        if (memoryConfig is null)
+        {
+            throw new ConfigurationException($"Unable to load Kernel Memory settings from the given configuration. " +
+                                             $"There should be a '{KernelMemoryComposer.ConfigRoot}' root node, " +
+                                             $"with data mapping to '{nameof(KernelMemoryConfig)}'");
+        }
+
+        var composer = new KernelMemoryComposer(builder, appSettings, memoryConfig);
+        composer.ConfigureBuilder();
+
+        return builder;
+    }
+}

service/Service/ConfigurationBuilderExtensions.cs → service/Core/Configuration/ConfigurationBuilderExtensions.cs

@@ -5,22 +5,27 @@
 using System.Reflection;
 using Microsoft.Extensions.Configuration;
 
-namespace Microsoft.KernelMemory.Service;
+#pragma warning disable IDE0130 // reduce number of "using" statements
+// ReSharper disable once CheckNamespace - reduce number of "using" statements
+namespace Microsoft.KernelMemory;
 
-internal static class ConfigurationBuilderExtensions
+public static partial class ConfigurationBuilderExtensions
 {
     // ASP.NET env var
-    private const string AspnetEnvVar = "ASPNETCORE_ENVIRONMENT";
+    private const string AspNetCoreEnvVar = "ASPNETCORE_ENVIRONMENT";
 
-    public static void AddKMConfigurationSources(
+    // .NET env var
+    private const string DotNetEnvVar = "DOTNET_ENVIRONMENT";
+
+    public static void AddKernelMemoryConfigurationSources(
         this IConfigurationBuilder builder,
         bool useAppSettingsFiles = true,
         bool useEnvVars = true,
         bool useSecretManager = true,
         string? settingsDirectory = null)
     {
-        // Load env var name, either Development or Production
-        var env = Environment.GetEnvironmentVariable(AspnetEnvVar) ?? string.Empty;
+        // ASPNETCORE_ENVIRONMENT env var takes precedence. Env should be either Development or Production.
+        var env = Environment.GetEnvironmentVariable(AspNetCoreEnvVar) ?? Environment.GetEnvironmentVariable(DotNetEnvVar) ?? string.Empty;
 
         // Detect the folder containing configuration files
         settingsDirectory ??= Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)

service/Service/Program.cs

@@ -57,7 +57,7 @@ public static void Main(string[] args)
 
         // *************************** CONFIG WIZARD ***************************
 
-        // Run `dotnet run setup` to run this code and setup the service
+        // Run `dotnet run setup` to run this code and set up the service
         if (new[] { "setup", "-setup", "config" }.Contains(args.FirstOrDefault(), StringComparer.OrdinalIgnoreCase))
         {
             InteractiveSetup.Main.InteractiveSetup(args.Skip(1).ToArray());
@@ -77,7 +77,8 @@ public static void Main(string[] args)
             appBuilder.Services.AddApplicationInsightsTelemetry();
         }
 
-        appBuilder.Configuration.AddKMConfigurationSources();
+        // Add config files, user secretes, and env vars
+        appBuilder.Configuration.AddKernelMemoryConfigurationSources();
 
         // Read KM settings, needed before building the app.
         KernelMemoryConfig config = appBuilder.Configuration.GetSection("KernelMemory").Get<KernelMemoryConfig>()
@@ -90,7 +91,8 @@ public static void Main(string[] args)
         // Internally build the memory client and make it available for dependency injection
         appBuilder.AddKernelMemory(memoryBuilder =>
             {
-                memoryBuilder.FromAppSettings().WithoutDefaultHandlers();
+                // Prepare the builder with settings from config files
+                memoryBuilder.ConfigureDependencies(appBuilder.Configuration).WithoutDefaultHandlers();
 
                 // When using distributed orchestration, handlers are hosted in the current app and need to be con
                 asyncHandlersCount = AddHandlersAsHostedServices(config, memoryBuilder, appBuilder);