Custom Handler Proxying (#11035)

satvu · web-flow · commit 7324b15775ad · 2025-06-13T13:08:18.000-07:00
diff --git a/release_notes.md b/release_notes.md
@@ -17,4 +17,5 @@
 - Improvements to coldstart pipeline (#11102).
 - Update Python Worker Version to [4.38.0](https://github.com/Azure/azure-functions-python-worker/releases/tag/4.38.0)
 - Only start the Diagnostic Events flush logs timer when events are present, preventing unnecessary flush attempts (#11100).
+- Enable HTTP proxying for custom handlers (#11035)
 - Switched memory usage reporting to use CGroup metrics by default for Linux consumption (#11114)
diff --git a/src/WebJobs.Script.Grpc/Channel/GrpcWorkerChannel.cs b/src/WebJobs.Script.Grpc/Channel/GrpcWorkerChannel.cs
@@ -26,6 +26,7 @@
 using Microsoft.Azure.WebJobs.Script.Grpc.Eventing;
 using Microsoft.Azure.WebJobs.Script.Grpc.Extensions;
 using Microsoft.Azure.WebJobs.Script.Grpc.Messages;
+using Microsoft.Azure.WebJobs.Script.Http;
 using Microsoft.Azure.WebJobs.Script.ManagedDependencies;
 using Microsoft.Azure.WebJobs.Script.Workers;
 using Microsoft.Azure.WebJobs.Script.Workers.Rpc;
diff --git a/src/WebJobs.Script.Grpc/Channel/GrpcWorkerChannelFactory.cs b/src/WebJobs.Script.Grpc/Channel/GrpcWorkerChannelFactory.cs
@@ -8,6 +8,7 @@
 using Microsoft.Azure.WebJobs.Script.Diagnostics;
 using Microsoft.Azure.WebJobs.Script.Eventing;
 using Microsoft.Azure.WebJobs.Script.Grpc.Eventing;
+using Microsoft.Azure.WebJobs.Script.Http;
 using Microsoft.Azure.WebJobs.Script.Workers;
 using Microsoft.Azure.WebJobs.Script.Workers.Rpc;
 using Microsoft.Azure.WebJobs.Script.Workers.SharedMemoryDataTransfer;
diff --git a/src/WebJobs.Script.Grpc/GrpcServiceCollectionsExtensions.cs b/src/WebJobs.Script.Grpc/GrpcServiceCollectionsExtensions.cs
@@ -2,6 +2,7 @@
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 using Microsoft.Azure.WebJobs.Script.Grpc.Messages;
+using Microsoft.Azure.WebJobs.Script.Http;
 using Microsoft.Azure.WebJobs.Script.Workers.Rpc;
 using Microsoft.Extensions.DependencyInjection;
 
diff --git a/src/WebJobs.Script.Grpc/WebJobs.Script.Grpc.csproj b/src/WebJobs.Script.Grpc/WebJobs.Script.Grpc.csproj
@@ -18,7 +18,6 @@
     <PackageReference Include="System.IO.FileSystem.Primitives" Version="4.3.0" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.556" PrivateAssets="all" />
     <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
-    <PackageReference Include="Yarp.ReverseProxy" Version="2.0.1" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/WebJobs.Script.WebHost/Middleware/FunctionInvocationMiddleware.cs b/src/WebJobs.Script.WebHost/Middleware/FunctionInvocationMiddleware.cs
@@ -4,10 +4,8 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Authorization.Policy;
-using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.Abstractions;
@@ -57,9 +55,9 @@ public async Task Invoke(HttpContext context)
                 int nestedProxiesCount = GetNestedProxiesCount(context, functionExecution);
                 IActionResult result = await GetResultAsync(context, functionExecution);
 
-                if (context.Items.TryGetValue(ScriptConstants.HttpProxyingEnabled, out var value))
+                if (context.Items.TryGetValue(ScriptConstants.HttpProxyingEnabled, out var httpProxyingEnabled))
                 {
-                    if (value?.ToString() == bool.TrueString)
+                    if (httpProxyingEnabled?.ToString() == bool.TrueString)
                     {
                         return;
                     }
diff --git a/src/WebJobs.Script/Description/Workers/ScriptInvocationResult.cs b/src/WebJobs.Script/Description/Workers/ScriptInvocationResult.cs
@@ -2,11 +2,17 @@
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using System.Collections.Immutable;
 
 namespace Microsoft.Azure.WebJobs.Script.Description
 {
     public class ScriptInvocationResult
     {
+        public static readonly ScriptInvocationResult Success = new ScriptInvocationResult
+        {
+            Outputs = ImmutableDictionary<string, object>.Empty
+        };
+
         public object Return { get; set; }
 
         public IDictionary<string, object> Outputs { get; set; }
diff --git a/src/WebJobs.Script/Exceptions/HttpForwardingException.cs b/src/WebJobs.Script/Exceptions/HttpForwardingException.cs
@@ -3,7 +3,7 @@
 
 using System;
 
-namespace Microsoft.Azure.WebJobs.Script.Grpc.Exceptions
+namespace Microsoft.Azure.WebJobs.Script.Exceptions
 {
     internal class HttpForwardingException : Exception
     {
diff --git a/src/WebJobs.Script/Http/DefaultHttpProxyService.cs b/src/WebJobs.Script/Http/DefaultHttpProxyService.cs
@@ -7,12 +7,12 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Azure.WebJobs.Script.Description;
-using Microsoft.Azure.WebJobs.Script.Grpc.Exceptions;
+using Microsoft.Azure.WebJobs.Script.Exceptions;
 using Microsoft.Azure.WebJobs.Script.Workers;
 using Microsoft.Extensions.Logging;
 using Yarp.ReverseProxy.Forwarder;
 
-namespace Microsoft.Azure.WebJobs.Script.Grpc
+namespace Microsoft.Azure.WebJobs.Script.Http
 {
     internal class DefaultHttpProxyService : IHttpProxyService, IDisposable
     {
diff --git a/src/WebJobs.Script/Http/DefaultHttpRouteManager.cs b/src/WebJobs.Script/Http/DefaultHttpRouteManager.cs
@@ -1,9 +1,6 @@
 ﻿// 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 Microsoft.Azure.WebJobs.Script.WebHost;
-
 namespace Microsoft.Azure.WebJobs.Script.Http
 {
     internal class DefaultHttpRouteManager : IHttpRoutesManager
diff --git a/src/WebJobs.Script/Http/IHttpProxyService.cs b/src/WebJobs.Script/Http/IHttpProxyService.cs
@@ -5,7 +5,7 @@
 using System.Threading.Tasks;
 using Microsoft.Azure.WebJobs.Script.Description;
 
-namespace Microsoft.Azure.WebJobs.Script.Grpc
+namespace Microsoft.Azure.WebJobs.Script.Http
 {
     public interface IHttpProxyService
     {
diff --git a/src/WebJobs.Script/Http/IHttpRoutesManager.cs b/src/WebJobs.Script/Http/IHttpRoutesManager.cs
@@ -1,8 +1,6 @@
 ﻿// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
-using System;
-
 namespace Microsoft.Azure.WebJobs.Script
 {
     public interface IHttpRoutesManager
diff --git a/src/WebJobs.Script/Http/RetryProxyHandler.cs b/src/WebJobs.Script/Http/RetryProxyHandler.cs
@@ -7,7 +7,7 @@
 using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
 
-namespace Microsoft.Azure.WebJobs.Script.Grpc
+namespace Microsoft.Azure.WebJobs.Script.Http
 {
     internal sealed class RetryProxyHandler : DelegatingHandler
     {
diff --git a/src/WebJobs.Script/WebJobs.Script.csproj b/src/WebJobs.Script/WebJobs.Script.csproj
@@ -73,6 +73,7 @@
     <PackageReference Include="System.Text.Json" Version="8.0.5" />
     <PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
     <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
+    <PackageReference Include="Yarp.ReverseProxy" Version="2.0.1" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/WebJobs.Script/Workers/Http/Configuration/HttpWorkerOptions.cs b/src/WebJobs.Script/Workers/Http/Configuration/HttpWorkerOptions.cs
@@ -15,8 +15,19 @@ public class HttpWorkerOptions
 
         public int Port { get; set; }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether the host will forward the request to the worker process.
+        /// </summary>
+        /// <remarks>
+        /// The host will rebuild the initial invocation HTTP Request and send the copy to the worker process.
+        /// </remarks>
         public bool EnableForwardingHttpRequest { get; set; }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether the host will proxy the invocation HTTP request to the worker process.
+        /// </summary>
+        public bool EnableProxyingHttpRequest { get; set; }
+
         public TimeSpan InitializationTimeout { get; set; } = TimeSpan.FromSeconds(30);
     }
 }
diff --git a/src/WebJobs.Script/Workers/Http/Configuration/HttpWorkerOptionsSetup.cs b/src/WebJobs.Script/Workers/Http/Configuration/HttpWorkerOptionsSetup.cs
@@ -46,7 +46,7 @@ public void Configure(HttpWorkerOptions options)
                 ConfigureWorkerDescription(options, customHandlerSection);
                 if (options.Type == CustomHandlerType.None)
                 {
-                    // CustomHandlerType.None is only for maitaining backward compatibilty with httpWorker section.
+                    // CustomHandlerType.None is only for maintaining backward compatability with httpWorker section.
                     _logger.LogWarning($"CustomHandlerType {CustomHandlerType.None} is not supported. Defaulting to {CustomHandlerType.Http}.");
                     options.Type = CustomHandlerType.Http;
                 }
diff --git a/src/WebJobs.Script/Workers/Http/DefaultHttpWorkerService.cs b/src/WebJobs.Script/Workers/Http/DefaultHttpWorkerService.cs
@@ -13,6 +13,7 @@
 using Microsoft.Azure.WebJobs.Script.Description;
 using Microsoft.Azure.WebJobs.Script.Diagnostics.Extensions;
 using Microsoft.Azure.WebJobs.Script.Extensions;
+using Microsoft.Azure.WebJobs.Script.Http;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 
@@ -24,17 +25,23 @@ public class DefaultHttpWorkerService : IHttpWorkerService
         private readonly HttpWorkerOptions _httpWorkerOptions;
         private readonly ILogger _logger;
         private readonly bool _enableRequestTracing;
+        private readonly IHttpProxyService _httpProxyService;
+        private readonly Uri _destinationPrefix;
+        private readonly string _userAgentString;
 
-        public DefaultHttpWorkerService(IOptions<HttpWorkerOptions> httpWorkerOptions, ILoggerFactory loggerFactory, IEnvironment environment, IOptions<ScriptJobHostOptions> scriptHostOptions)
-            : this(CreateHttpClient(httpWorkerOptions), httpWorkerOptions, loggerFactory.CreateLogger<DefaultHttpWorkerService>(), environment, scriptHostOptions)
+        public DefaultHttpWorkerService(IOptions<HttpWorkerOptions> httpWorkerOptions, ILoggerFactory loggerFactory, IEnvironment environment,
+            IOptions<ScriptJobHostOptions> scriptHostOptions, IHttpProxyService httpProxyService)
+            : this(CreateHttpClient(httpWorkerOptions), httpWorkerOptions, loggerFactory.CreateLogger<DefaultHttpWorkerService>(), environment, scriptHostOptions, httpProxyService)
         {
         }
 
-        internal DefaultHttpWorkerService(HttpClient httpClient, IOptions<HttpWorkerOptions> httpWorkerOptions, ILogger logger, IEnvironment environment, IOptions<ScriptJobHostOptions> scriptHostOptions)
+        internal DefaultHttpWorkerService(HttpClient httpClient, IOptions<HttpWorkerOptions> httpWorkerOptions, ILogger logger, IEnvironment environment,
+            IOptions<ScriptJobHostOptions> scriptHostOptions, IHttpProxyService httpProxyService)
         {
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
             _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
             _httpWorkerOptions = httpWorkerOptions.Value ?? throw new ArgumentNullException(nameof(httpWorkerOptions.Value));
+            _httpProxyService = httpProxyService ?? throw new ArgumentNullException(nameof(httpProxyService));
             _enableRequestTracing = environment.IsCoreTools();
             if (scriptHostOptions.Value.FunctionTimeout == null)
             {
@@ -47,6 +54,9 @@ internal DefaultHttpWorkerService(HttpClient httpClient, IOptions<HttpWorkerOpti
                 // Set 1 minute greater than FunctionTimeout to ensure invoction failure due to timeout is raised before httpClient raises operation cancelled exception
                 _httpClient.Timeout = scriptHostOptions.Value.FunctionTimeout.Value.Add(TimeSpan.FromMinutes(1));
             }
+
+            _destinationPrefix = new UriBuilder(WorkerConstants.HttpScheme, WorkerConstants.HostName, _httpWorkerOptions.Port).Uri;
+            _userAgentString = $"{HttpWorkerConstants.UserAgentHeaderValue}/{ScriptHost.Version}";
         }
 
         private static HttpClient CreateHttpClient(IOptions<HttpWorkerOptions> httpWorkerOptions)
@@ -61,16 +71,44 @@ public Task InvokeAsync(ScriptInvocationContext scriptInvocationContext)
         {
             if (scriptInvocationContext.FunctionMetadata.IsHttpInAndOutFunction())
             {
+                if (_httpWorkerOptions.EnableProxyingHttpRequest)
+                {
+                    return ProxyInvocationRequest(scriptInvocationContext);
+                }
+
                 // type is empty for httpWorker section. EnableForwardingHttpRequest is opt-in for custom handler section.
                 if (_httpWorkerOptions.Type == CustomHandlerType.None || _httpWorkerOptions.EnableForwardingHttpRequest)
                 {
                     return ProcessHttpInAndOutInvocationRequest(scriptInvocationContext);
                 }
-                return ProcessDefaultInvocationRequest(scriptInvocationContext);
             }
+
             return ProcessDefaultInvocationRequest(scriptInvocationContext);
         }
 
+        internal async Task ProxyInvocationRequest(ScriptInvocationContext scriptInvocationContext)
+        {
+            try
+            {
+                if (!scriptInvocationContext.TryGetHttpRequest(out HttpRequest httpRequest))
+                {
+                    throw new InvalidOperationException($"Cannot proxy the HttpTrigger function {scriptInvocationContext.FunctionMetadata.Name} without an input of type {nameof(HttpRequest)}.");
+                }
+
+                AddProxyingHeaders(httpRequest, scriptInvocationContext.ExecutionContext.InvocationId.ToString());
+
+                // YARP only requires the destination prefix. The path and query string are added by the YARP proxy during SendAsync using info from the HttpContext.
+                _httpProxyService.StartForwarding(scriptInvocationContext, _destinationPrefix);
+
+                await _httpProxyService.EnsureSuccessfulForwardingAsync(scriptInvocationContext); // this will throw if forwarding is unsuccessful
+                scriptInvocationContext.ResultSource.SetResult(ScriptInvocationResult.Success);
+            }
+            catch (Exception exc)
+            {
+                scriptInvocationContext.ResultSource.TrySetException(exc);
+            }
+        }
+
         internal async Task ProcessHttpInAndOutInvocationRequest(ScriptInvocationContext scriptInvocationContext)
         {
             _logger.CustomHandlerForwardingHttpTriggerInvocation(scriptInvocationContext.FunctionMetadata.Name, scriptInvocationContext.ExecutionContext.InvocationId);
@@ -162,7 +200,14 @@ internal void AddHeaders(HttpRequestMessage httpRequest, string invocationId)
         {
             httpRequest.Headers.Add(HttpWorkerConstants.HostVersionHeaderName, ScriptHost.Version);
             httpRequest.Headers.Add(HttpWorkerConstants.InvocationIdHeaderName, invocationId);
-            httpRequest.Headers.UserAgent.ParseAdd($"{HttpWorkerConstants.UserAgentHeaderValue}/{ScriptHost.Version}");
+            httpRequest.Headers.UserAgent.ParseAdd(_userAgentString);
+        }
+
+        private void AddProxyingHeaders(HttpRequest httpRequest, string invocationId)
+        {
+            // if there are existing headers, override them
+            httpRequest.Headers[HttpWorkerConstants.HostVersionHeaderName] = ScriptHost.Version;
+            httpRequest.Headers[HttpWorkerConstants.InvocationIdHeaderName] = invocationId;
         }
 
         internal string GetPathValue(HttpWorkerOptions httpWorkerOptions, string functionName, HttpRequest httpRequest)
diff --git a/test/WebJobs.Script.Tests.Integration/ApplicationInsights/ApplicationInsightsTestFixture.cs b/test/WebJobs.Script.Tests.Integration/ApplicationInsights/ApplicationInsightsTestFixture.cs
@@ -11,6 +11,7 @@
 using Microsoft.Azure.WebJobs.Script.Diagnostics;
 using Microsoft.Azure.WebJobs.Script.Eventing;
 using Microsoft.Azure.WebJobs.Script.Grpc;
+using Microsoft.Azure.WebJobs.Script.Http;
 using Microsoft.Azure.WebJobs.Script.Workers;
 using Microsoft.Azure.WebJobs.Script.Workers.Rpc;
 using Microsoft.Azure.WebJobs.Script.Workers.SharedMemoryDataTransfer;
diff --git a/test/WebJobs.Script.Tests/HttpProxyService/DefaultHttpProxyServiceTests.cs b/test/WebJobs.Script.Tests/HttpProxyService/DefaultHttpProxyServiceTests.cs
@@ -6,7 +6,7 @@
 using System.Linq;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Azure.WebJobs.Script.Description;
-using Microsoft.Azure.WebJobs.Script.Grpc;
+using Microsoft.Azure.WebJobs.Script.Http;
 using Microsoft.Extensions.Logging;
 using Moq;
 using Xunit;
diff --git a/test/WebJobs.Script.Tests/HttpWorker/DefaultHttpWorkerServiceTests.cs b/test/WebJobs.Script.Tests/HttpWorker/DefaultHttpWorkerServiceTests.cs
diff --git a/test/WebJobs.Script.Tests/Workers/RetryProxyHandlerTests.cs b/test/WebJobs.Script.Tests/Workers/RetryProxyHandlerTests.cs
diff --git a/test/WebJobs.Script.Tests/Workers/Rpc/GrpcWorkerChannelTests.cs b/test/WebJobs.Script.Tests/Workers/Rpc/GrpcWorkerChannelTests.cs

Original file line number	Diff line number	Diff line change
`@@ -3,7 +3,7 @@`
`3`	`3`
`4`	`4`	`using System;`
`5`	`5`
`6`		`-namespace Microsoft.Azure.WebJobs.Script.Grpc.Exceptions`
	`6`	`+namespace Microsoft.Azure.WebJobs.Script.Exceptions`
`7`	`7`	`{`
`8`	`8`	`internal class HttpForwardingException : Exception`
`9`	`9`	`{`
Original file line number	Diff line number	Diff line change
`@@ -7,12 +7,12 @@`
`7`	`7`	`using System.Threading.Tasks;`
`8`	`8`	`using Microsoft.AspNetCore.Http;`
`9`	`9`	`using Microsoft.Azure.WebJobs.Script.Description;`
`10`		`-using Microsoft.Azure.WebJobs.Script.Grpc.Exceptions;`
	`10`	`+using Microsoft.Azure.WebJobs.Script.Exceptions;`
`11`	`11`	`using Microsoft.Azure.WebJobs.Script.Workers;`
`12`	`12`	`using Microsoft.Extensions.Logging;`
`13`	`13`	`using Yarp.ReverseProxy.Forwarder;`
`14`	`14`
`15`		`-namespace Microsoft.Azure.WebJobs.Script.Grpc`
	`15`	`+namespace Microsoft.Azure.WebJobs.Script.Http`
`16`	`16`	`{`
`17`	`17`	`internal class DefaultHttpProxyService : IHttpProxyService, IDisposable`
`18`	`18`	`{`
Original file line number	Diff line number	Diff line change
`@@ -1,9 +1,6 @@`
`1`	`1`	`// Copyright (c) .NET Foundation. All rights reserved.`
`2`	`2`	`// Licensed under the MIT License. See License.txt in the project root for license information.`
`3`	`3`
`4`		`-using System;`
`5`		`-using Microsoft.Azure.WebJobs.Script.WebHost;`
`6`		`-`
`7`	`4`	`namespace Microsoft.Azure.WebJobs.Script.Http`
`8`	`5`	`{`
`9`	`6`	`internal class DefaultHttpRouteManager : IHttpRoutesManager`