Introduce a Lightweight Scaling Package for Multi Durable Backends

Directory.Packages.props

@@ -8,9 +8,9 @@
   </PropertyGroup>
   <!-- Product dependencies -->
   <ItemGroup>
-    <PackageVersion Include="Azure.Identity" Version="1.12.1" />
+    <PackageVersion Include="Azure.Identity" Version="1.14.2" />
     <PackageVersion Include="Grpc.Tools" Version="2.49.0" />
-    <PackageVersion Include="Grpc.Net.Client" Version="2.70.0" />
+    <PackageVersion Include="Grpc.Net.Client" Version="2.71.0" />
     <PackageVersion Include="Microsoft.AspNetCore.Http.Abstractions" Version="2.3.0" />
     <PackageVersion Include="Microsoft.AspNetCore.Mvc.WebApiCompatShim" Version="2.2.0" />
     <PackageVersion Include="Microsoft.Azure.DurableTask.ApplicationInsights" Version="0.8.0" />
@@ -31,6 +31,9 @@
     <PackageVersion Include="Microsoft.DurableTask.Worker.Grpc" Version="1.16.1" />
     <PackageVersion Include="Microsoft.DurableTask.Abstractions" Version="1.16.1" />
     <PackageVersion Include="Microsoft.DurableTask.Analyzers" Version="0.1.0" />
+    <PackageVersion Include="Microsoft.DurableTask.AzureManagedBackend" Version="0.4.3-alpha" />
+    <PackageVersion Include="Microsoft.DurableTask.SqlServer" Version="1.5.2" />
+    <PackageVersion Include="Microsoft.Data.SqlClient" Version="5.1.2" />
     <PackageVersion Include="Microsoft.Extensions.Azure" Version="1.7.0" />
     <PackageVersion Include="Microsoft.Extensions.Caching.Memory" Version="6.0.3" />
     <PackageVersion Include="Microsoft.Extensions.Http" Version="6.0.0" />

WebJobs.Extensions.DurableTask.sln

@@ -62,6 +62,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DotNetIsolated", "test\Smok
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Worker.Extensions.DurableTask", "src\Worker.Extensions.DurableTask\Worker.Extensions.DurableTask.csproj", "{5F5FAF27-D6B8-4A60-ACF2-F63D13F89CA2}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "WebJobs.Extensions.DurableTask.Scale", "src\WebJobs.Extensions.DurableTask.Scale\WebJobs.Extensions.DurableTask.Scale.csproj", "{A2E5E1B2-2B4B-4B6F-A0A7-6D7E0E68F1C9}"
+EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "pipelines", "pipelines", "{B7FBBE6E-9AC7-4CEB-9B80-6FD9AE74415A}"
 	ProjectSection(SolutionItems) = preProject
 		azure-pipelines.yml = azure-pipelines.yml
@@ -126,6 +128,10 @@ Global
 		{5F5FAF27-D6B8-4A60-ACF2-F63D13F89CA2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{5F5FAF27-D6B8-4A60-ACF2-F63D13F89CA2}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{5F5FAF27-D6B8-4A60-ACF2-F63D13F89CA2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A2E5E1B2-2B4B-4B6F-A0A7-6D7E0E68F1C9}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A2E5E1B2-2B4B-4B6F-A0A7-6D7E0E68F1C9}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A2E5E1B2-2B4B-4B6F-A0A7-6D7E0E68F1C9}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A2E5E1B2-2B4B-4B6F-A0A7-6D7E0E68F1C9}.Release|Any CPU.Build.0 = Release|Any CPU
 		{FC8AD123-F949-4D21-B817-E5A4BBF7F69B}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{FC8AD123-F949-4D21-B817-E5A4BBF7F69B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{FC8AD123-F949-4D21-B817-E5A4BBF7F69B}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -162,6 +168,7 @@ Global
 		{9B0F4A0A-1B18-4E98-850A-14A2F76F673D} = {A8CF6993-258A-484A-AF6D-6CC88D36AF93}
 		{FF6CD07A-A4BF-43C5-B14E-213328DEB835} = {9B0F4A0A-1B18-4E98-850A-14A2F76F673D}
 		{5F5FAF27-D6B8-4A60-ACF2-F63D13F89CA2} = {7EC858EE-3481-4A82-AED4-CB00C34F42D0}
+		{A2E5E1B2-2B4B-4B6F-A0A7-6D7E0E68F1C9} = {7EC858EE-3481-4A82-AED4-CB00C34F42D0}
 		{7387E723-E153-4B7A-B105-8C67BFBD48CF} = {78BCF152-C22C-408F-9FB1-0F8C99B154B5}
 		{FC8AD123-F949-4D21-B817-E5A4BBF7F69B} = {7387E723-E153-4B7A-B105-8C67BFBD48CF}
 		{76DEC17C-BF6A-498A-8E8A-7D6CB2E03284} = {78BCF152-C22C-408F-9FB1-0F8C99B154B5}

src/WebJobs.Extensions.DurableTask.Scale/AzureManaged/AzureManagedConnectionString.cs

@@ -0,0 +1,51 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using System.Data.Common;
+
+namespace Microsoft.Azure.WebJobs.Extensions.DurableTask.Scale.AzureManaged
+{
+    /// <summary>
+    /// Connection string to conenct to AzureManaged backend service.
+    /// </summary>
+    public sealed class AzureManagedConnectionString
+    {
+        private readonly DbConnectionStringBuilder builder;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AzureManagedConnectionString"/> class.
+        /// </summary>
+        /// <param name="connectionString">A connection string for an Azure-managed durable task service.</param>
+        public AzureManagedConnectionString(string connectionString)
+        {
+            this.builder = new DbConnectionStringBuilder { ConnectionString = connectionString };
+        }
+
+        /// <summary>
+        /// Gets the authentication method specified in the connection string (if any).
+        /// </summary>
+        public string Authentication => this.GetValue("Authentication");
+
+        /// <summary>
+        /// Gets the managed identity or workload identity client ID specified in the connection string (if any).
+        /// </summary>
+        public string ClientId => this.GetValue("ClientID");
+
+        /// <summary>
+        /// Gets the endpoint specified in the connection string (if any).
+        /// </summary>
+        public string Endpoint => this.GetValue("Endpoint");
+
+        /// <summary>
+        /// Gets the task hub name specified in the connection string (if any).
+        /// </summary>
+        public string TaskHubName => this.GetValue("TaskHub");
+
+        private string GetValue(string name)
+        {
+            return this.builder.TryGetValue(name, out object value)
+                ? value as string
+                : null;
+        }
+    }
+}

src/WebJobs.Extensions.DurableTask.Scale/AzureManaged/AzureManagedScalabilityProvider.cs

@@ -0,0 +1,99 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using System;
+using Microsoft.Azure.WebJobs.Host.Scale;
+using Microsoft.DurableTask.AzureManagedBackend;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.Azure.WebJobs.Extensions.DurableTask.Scale.AzureManaged
+{
+    /// <summary>
+    /// The AzureManaged backend implementation of the scalability provider for Durable Functions.
+    /// </summary>
+    public class AzureManagedScalabilityProvider : ScalabilityProvider
+    {
+        private readonly AzureManagedOrchestrationService orchestrationService;
+        private readonly string connectionName;
+        private readonly ILogger logger;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AzureManagedScalabilityProvider"/> class.
+        /// </summary>
+        /// <param name="orchestrationService">
+        /// The <see cref="AzureManagedOrchestrationService"/> instance that provides access to backend service for scaling operations.
+        /// </param>
+        /// <param name="connectionName">
+        /// The logical name of the storage or service connection associated with this provider.
+        /// </param>
+        /// <param name="logger">
+        /// The <see cref="ILogger"/> instance used for logging provider activities and diagnostics.
+        /// </param>
+        /// <exception cref="ArgumentNullException">
+        /// Thrown if <paramref name="orchestrationService"/> is <see langword="null"/>.
+        /// </exception>
+        public AzureManagedScalabilityProvider(
+            AzureManagedOrchestrationService orchestrationService,
+            string connectionName,
+            ILogger logger)
+            : base("AzureManaged", connectionName)
+        {
+            this.orchestrationService = orchestrationService ?? throw new ArgumentNullException(nameof(orchestrationService));
+            this.connectionName = connectionName;
+            this.logger = logger;
+        }
+
+        /// <summary>
+        /// The app setting containing the Azure Managed connection string.
+        /// </summary>
+        public override string ConnectionName => this.connectionName;
+
+        /// <inheritdoc/>
+        /// This is not used.
+        public override bool TryGetScaleMonitor(
+            string functionId,
+            string functionName,
+            string hubName,
+            string connectionName,
+            out IScaleMonitor scaleMonitor)
+        {
+            // Azure Managed backend does not support the legacy scale monitor infrastructure.
+            // Return a dummy scale monitor to avoid exceptions.
+            scaleMonitor = new DummyScaleMonitor(functionId, hubName);
+            return true;
+        }
+
+        /// <inheritdoc/>
+        public override bool TryGetTargetScaler(
+            string functionId,
+            string functionName,
+            string hubName,
+            string connectionName,
+            out ITargetScaler targetScaler)
+        {
+            // Create a target scaler that uses the orchestration service's metrics endpoint.
+            // All target scalers share the same AzureManagedOrchestrationService in the same task hub.
+            targetScaler = new AzureManagedTargetScaler(this.orchestrationService, functionId);
+            return true;
+        }
+
+        private class DummyScaleMonitor : IScaleMonitor
+        {
+            private static readonly ScaleMetrics DummyScaleMetrics = new ScaleMetrics();
+            private static readonly ScaleStatus DummyScaleStatus = new ScaleStatus();
+
+            public DummyScaleMonitor(string functionId, string taskHub)
+            {
+                this.Descriptor = new ScaleMonitorDescriptor(
+                    id: $"DurableTask.AzureManaged:{taskHub ?? "default"}",
+                    functionId);
+            }
+
+            public ScaleMonitorDescriptor Descriptor { get; }
+
+            public System.Threading.Tasks.Task<ScaleMetrics> GetMetricsAsync() => System.Threading.Tasks.Task.FromResult(DummyScaleMetrics);
+
+            public ScaleStatus GetScaleStatus(ScaleStatusContext context) => DummyScaleStatus;
+        }
+    }
+}

src/WebJobs.Extensions.DurableTask.Scale/AzureManaged/AzureManagedScalabilityProviderExtensions.cs

@@ -0,0 +1,21 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Microsoft.Azure.WebJobs.Extensions.DurableTask.Scale.AzureManaged
+{
+    /// <summary>
+    /// Extension methods for configuring the Azure Managed Durable Task backend.
+    /// </summary>
+    public static class AzureManagedScalabilityProviderExtensions
+    {
+        /// <summary>
+        /// Registers the Azure Managed Durable Task backend with the dependency injection container.
+        /// </summary>
+        public static void AddDurableTaskManagedBackend(this IServiceCollection services)
+        {
+            services.AddSingleton<IScalabilityProviderFactory, AzureManagedScalabilityProviderFactory>();
+        }
+    }
+}