Refactor func metadata to allow multiple sources

sdk/Sdk.Generators/FunctionMetadataProviderGenerator/FunctionMetadataProviderGenerator.Emitter.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
@@ -23,56 +23,72 @@ public static string Emit(GeneratorExecutionContext context, IReadOnlyList<Gener
             {
                 string functionMetadataInfo = AddFunctionMetadataInfo(funcMetadata, context.CancellationToken);
 
+                // Note: we still emit `IFunctionMetadataProvider` contract to avoid a breaking change, but it is no longer used for this extension point.
                 return $$"""
-                         // <auto-generated/>
-                         using System;
-                         using System.Collections.Generic;
-                         using System.Collections.Immutable;
-                         using System.Text.Json;
-                         using System.Threading.Tasks;
-                         using Microsoft.Azure.Functions.Worker;
-                         using Microsoft.Azure.Functions.Worker.Core.FunctionMetadata;
-                         using Microsoft.Extensions.DependencyInjection;
-                         using Microsoft.Extensions.Hosting;
-
-                         namespace {{FunctionsUtil.GetNamespaceForGeneratedCode(context)}}
-                         {
-                             /// <summary>
-                             /// Custom <see cref="IFunctionMetadataProvider"/> implementation that returns function metadata definitions for the current worker."/>
-                             /// </summary>
-                             [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Never)]
-                             [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
-                             public class GeneratedFunctionMetadataProvider : IFunctionMetadataProvider
-                             {
-                                 /// <inheritdoc/>
-                                 public Task<ImmutableArray<IFunctionMetadata>> GetFunctionMetadataAsync(string directory)
-                                 {
-                                     var metadataList = new List<IFunctionMetadata>();
-                         {{functionMetadataInfo}}
-                                     return global::System.Threading.Tasks.Task.FromResult(metadataList.ToImmutableArray());
-                                 }
-                             }
-
-                             /// <summary>
-                             /// Extension methods to enable registration of the custom <see cref="IFunctionMetadataProvider"/> implementation generated for the current worker.
-                             /// </summary>
-                             public static class WorkerHostBuilderFunctionMetadataProviderExtension
-                             {
-                                 ///<summary>
-                                 /// Adds the GeneratedFunctionMetadataProvider to the service collection.
-                                 /// During initialization, the worker will return generated function metadata instead of relying on the Azure Functions host for function indexing.
-                                 ///</summary>
-                                 public static IHostBuilder ConfigureGeneratedFunctionMetadataProvider(this IHostBuilder builder)
-                                 {
-                                     builder.ConfigureServices(s => 
-                                     {
-                                         s.AddSingleton<IFunctionMetadataProvider, GeneratedFunctionMetadataProvider>();
-                                     });
-                                     return builder;
-                                 }
-                             }{{GetAutoConfigureStartupClass(includeAutoRegistrationCode)}}
-                         }
-                         """;
+// <auto-generated/>
+
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using IHostBuilder = global::Microsoft.Extensions.Hosting.IHostBuilder;
+using WorkerOptions = global::Microsoft.Azure.Functions.Worker.WorkerOptions;
+using IFunctionMetadataSource = global::Microsoft.Azure.Functions.Worker.Core.FunctionMetadata.IFunctionMetadataSource;
+using IFunctionMetadata = global::Microsoft.Azure.Functions.Worker.Core.FunctionMetadata.IFunctionMetadata;
+using DefaultFunctionMetadata = global::Microsoft.Azure.Functions.Worker.Core.FunctionMetadata.DefaultFunctionMetadata;
+
+namespace {{FunctionsUtil.GetNamespaceForGeneratedCode(context)}}
+{
+    /// <summary>
+    /// Custom <see cref="IFunctionMetadataSource"/> implementation that returns function metadata definitions for the current worker.
+    /// </summary>
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Never)]
+    public class GeneratedFunctionMetadataProvider : IFunctionMetadataProvider, IFunctionMetadataSource
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="GeneratedFunctionMetadataProvider"/> class.
+        /// </summary>
+        public GeneratedFunctionMetadataProvider()
+        {
+            var metadataList = new global::System.Collections.Generic.List<IFunctionMetadata>();
+{{functionMetadataInfo}}
+            Metadata = metadataList;
+        }
+
+        /// <inheritdoc/>
+        public global::System.Collections.Generic.IReadOnlyList<IFunctionMetadata> Metadata { get; }
+
+        /// <inheritdoc/>
+        [global::System.Runtime.ObsoleteAttribute("IFunctionMetadataProvider.GetFunctionMetadataAsync is no longer used for function indexing with this class. Use IFunctionMetadataSource.Metadata instead.")]
+        public global::System.Threading.Tasks.Task<global::System.Collections.Immutable.ImmutableArray<IFunctionMetadata>> GetFunctionMetadataAsync(string directory)
+        {
+            return global::System.Threading.Tasks.Task.FromResult(global::System.Collections.Immutable.ImmutableArray.CreateRange(Metadata));
+        }
+    }
+
+    /// <summary>
+    /// Extension methods to enable registration of the custom <see cref="IFunctionMetadataSource"/> implementation generated for the current worker.
+    /// </summary>
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    public static class WorkerHostBuilderFunctionMetadataProviderExtension
+    {
+        ///<summary>
+        /// Adds the GeneratedFunctionMetadataProvider to the service collection.
+        /// During initialization, the worker will return generated function metadata instead of relying on the Azure Functions host for function indexing.
+        ///</summary>
+        public static IHostBuilder ConfigureGeneratedFunctionMetadataProvider(this IHostBuilder builder)
+        {
+            builder.ConfigureServices(s =>
+            {
+                s.TryAddEnumerable(global::Microsoft.Extensions.DependencyInjection.ServiceDescriptor.Singleton<IFunctionMetadataSource>(new GeneratedFunctionMetadataProvider()));
+                s.Configure<WorkerOptions>(options => options.Internal.DisableDefaultFunctionMetadata = true);
+            });
+            return builder;
+        }
+    }
+{{GetAutoConfigureStartupClass(includeAutoRegistrationCode)}}
+}
+
+""";
             }
 
             private static string GetAutoConfigureStartupClass(bool includeAutoRegistrationCode)
@@ -81,22 +97,23 @@ private static string GetAutoConfigureStartupClass(bool includeAutoRegistrationC
                 {
                     string result = $$"""
 
-                                      /// <summary>
-                                      /// Auto startup class to register the custom <see cref="IFunctionMetadataProvider"/> implementation generated for the current worker.
-                                      /// </summary>
-                                      [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Never)]
-                                      public class FunctionMetadataProviderAutoStartup : global::Microsoft.Azure.Functions.Worker.IAutoConfigureStartup
-                                      {
-                                          /// <summary>
-                                          /// Configures the <see cref="IHostBuilder"/> to use the custom <see cref="IFunctionMetadataProvider"/> implementation generated for the current worker.
-                                          /// </summary>
-                                          /// <param name="hostBuilder">The <see cref="IHostBuilder"/> instance to use for service registration.</param>
-                                          public void Configure(IHostBuilder hostBuilder)
-                                          {
-                                              hostBuilder.ConfigureGeneratedFunctionMetadataProvider();
-                                          }
-                                      }
-                                  """;
+    /// <summary>
+    /// Auto startup class to register the custom <see cref="IFunctionMetadataSource"/> implementation generated for the current worker.
+    /// </summary>
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Never)]
+    public class FunctionMetadataProviderAutoStartup : global::Microsoft.Azure.Functions.Worker.IAutoConfigureStartup
+    {
+        /// <summary>
+        /// Configures the <see cref="IHostBuilder"/> to use the custom <see cref="IFunctionMetadataSource"/> implementation generated for the current worker.
+        /// </summary>
+        /// <param name="hostBuilder">The <see cref="IHostBuilder"/> instance to use for service registration.</param>
+        public void Configure(IHostBuilder hostBuilder)
+        {
+            hostBuilder.ConfigureGeneratedFunctionMetadataProvider();
+        }
+    }
+""";
 
                     return result;
                 }

src/DotNetWorker.Core/FunctionMetadata/IFunctionMetadataProvider.cs

@@ -11,7 +11,6 @@ namespace Microsoft.Azure.Functions.Worker.Core.FunctionMetadata
     /// </summary>
     public interface IFunctionMetadataProvider
     {
-
         /// <summary>
         /// Gets all function metadata that this provider knows about asynchronously
         /// </summary>

src/DotNetWorker.Core/FunctionMetadata/IFunctionsMetadataSource.cs

@@ -0,0 +1,18 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace Microsoft.Azure.Functions.Worker.Core.FunctionMetadata
+{
+    /// <summary>
+    /// A source for providing metadata.
+    /// </summary>
+    public interface IFunctionMetadataSource
+    {
+        /// <summary>
+        /// Gets the function metadata.
+        /// </summary>
+        IReadOnlyList<IFunctionMetadata> Metadata { get; }
+    }
+}

src/DotNetWorker.Core/Hosting/WorkerOptions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Generic;
 using System.Text.Json;
 using Azure.Core.Serialization;
@@ -24,6 +25,12 @@ public class WorkerOptions
         /// </summary>
         public InputConverterCollection InputConverters { get; } = new InputConverterCollection();
 
+        /// <summary>
+        /// Gets the internal options.
+        /// </summary>
+        [Obsolete("This property is for internal use only and not expected to be called by user code.")]
+        public InternalOptions Internal { get; } = new InternalOptions();
+
         /// <summary>
         /// Gets the optional worker capabilities.
         /// </summary>
@@ -81,5 +88,16 @@ private void SetBoolCapability(string name, bool value)
                 Capabilities.Remove(name);
             }
         }
+
+        /// <summary>
+        /// Options for internal configurations. Typically not expected to be set by users.
+        /// </summary>
+        public class InternalOptions
+        {
+            /// <summary>
+            /// Gets or sets a value indicating whether to disable providing default function metadata (from functions.metadata).
+            /// </summary>
+            public bool DisableDefaultFunctionMetadata { get; set; }
+        }
     }
 }

src/DotNetWorker.Grpc/FunctionMetadata/DefaultFunctionMetadataProvider.cs

@@ -5,66 +5,40 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.IO;
+using System.Linq;
 using System.Text.Json;
 using System.Threading.Tasks;
 using Microsoft.Azure.Functions.Worker.Core.FunctionMetadata;
 using Microsoft.Azure.Functions.Worker.Grpc.Messages;
+using Microsoft.Extensions.Options;
 
 namespace Microsoft.Azure.Functions.Worker
 {
     internal class DefaultFunctionMetadataProvider : IFunctionMetadataProvider
     {
         private const string FileName = "functions.metadata";
-        private JsonSerializerOptions deserializationOptions;
 
-        public DefaultFunctionMetadataProvider()
+        private readonly IEnumerable<IFunctionMetadataSource> _sources;
+        private readonly WorkerOptions _options;
+        private readonly JsonSerializerOptions _deserializationOptions = new() { PropertyNameCaseInsensitive = true };
+
+        public DefaultFunctionMetadataProvider(IEnumerable<IFunctionMetadataSource> sources, IOptions<WorkerOptions> options)
         {
-            deserializationOptions = new JsonSerializerOptions();
-            deserializationOptions.PropertyNameCaseInsensitive = true;
+            _sources = sources;
+            _options = options.Value;
         }
 
         public virtual async Task<ImmutableArray<IFunctionMetadata>> GetFunctionMetadataAsync(string directory)
         {
-            string metadataFile = Path.Combine(directory, FileName);
+            ImmutableArray<IFunctionMetadata>.Builder builder = ImmutableArray.CreateBuilder<IFunctionMetadata>();
+            builder.AddRange(await GetDefaultFunctionMetadataAsync(directory));
 
-            if (!File.Exists(metadataFile))
+            foreach (var source in _sources)
             {
-                throw new FileNotFoundException($"Function metadata file not found. File path used:{metadataFile}");
+                builder.AddRange(source.Metadata);
             }
 
-            using (var fs = File.OpenRead(metadataFile))
-            {
-                // deserialize as json element to preserve raw bindings
-                var jsonMetadataList = await JsonSerializer.DeserializeAsync<JsonElement>(fs);
-
-                var functionMetadataResults = new List<IFunctionMetadata>(jsonMetadataList.GetArrayLength());
-
-                foreach (var jsonMetadata in jsonMetadataList.EnumerateArray())
-                {
-                    var functionMetadata = JsonSerializer.Deserialize<RpcFunctionMetadata>(jsonMetadata.GetRawText(), deserializationOptions);
-
-                    if (functionMetadata is null)
-                    {
-                        throw new NullReferenceException("Function metadata could not be found.");
-                    }
-
-                    // hard-coded values that are checked for when the host validates functions
-                    functionMetadata.IsProxy = false;
-                    functionMetadata.Language = "dotnet-isolated";
-                    functionMetadata.FunctionId = Guid.NewGuid().ToString();
-
-                    var rawBindings = GetRawBindings(jsonMetadata);
-
-                    foreach (var binding in rawBindings.EnumerateArray())
-                    {
-                        functionMetadata.RawBindings.Add(binding.GetRawText());
-                    }
-
-                    functionMetadataResults.Add(functionMetadata);
-                }
-
-                return functionMetadataResults.ToImmutableArray();
-            }
+            return builder.ToImmutable();
         }
 
         internal static JsonElement GetRawBindings(JsonElement jsonMetadata)
@@ -79,5 +53,49 @@ internal static JsonElement GetRawBindings(JsonElement jsonMetadata)
 
             return bindingsJson;
         }
+
+        private async Task<IEnumerable<IFunctionMetadata>> GetDefaultFunctionMetadataAsync(string directory)
+        {
+#pragma warning disable CS0618 // Type or member is obsolete
+            if (_options.Internal.DisableDefaultFunctionMetadata)
+            {
+                return Enumerable.Empty<IFunctionMetadata>();
+            }
+#pragma warning restore CS0618 // Type or member is obsolete
+
+            string metadataFile = Path.Combine(directory, FileName);
+            if (!File.Exists(metadataFile))
+            {
+                throw new FileNotFoundException($"Function metadata file not found. File path used:{metadataFile}");
+            }
+
+            using var fs = File.OpenRead(metadataFile);
+            // deserialize as json element to preserve raw bindings
+            var jsonMetadataList = await JsonSerializer.DeserializeAsync<JsonElement>(fs);
+            return ParseMetadata(jsonMetadataList);
+        }
+
+        private IEnumerable<IFunctionMetadata> ParseMetadata(JsonElement json)
+        {
+            foreach (var jsonMetadata in json.EnumerateArray())
+            {
+                var functionMetadata = JsonSerializer.Deserialize<RpcFunctionMetadata>(jsonMetadata.GetRawText(), _deserializationOptions)
+                    ?? throw new NullReferenceException("Function metadata could not be found.");
+
+                // hard-coded values that are checked for when the host validates functions
+                functionMetadata.IsProxy = false;
+                functionMetadata.Language = "dotnet-isolated";
+                functionMetadata.FunctionId = Guid.NewGuid().ToString();
+
+                var rawBindings = GetRawBindings(jsonMetadata);
+
+                foreach (var binding in rawBindings.EnumerateArray())
+                {
+                    functionMetadata.RawBindings.Add(binding.GetRawText());
+                }
+
+                yield return functionMetadata;
+            }
+        }
     }
 }