HeaderPropagation Middleware: configuration per client (#10096)

* HeaderPropagation Middleware: configuration per client

* Renamed fields

* Renamed fields

* Fix sample

* Addressed feedback, cleaned up and added tests

* Addressed feedback on HeaderPropagationHttpClientBuilderExtensions

* Updated reference assemblies

Author: alefranz

src/Middleware/HeaderPropagation/ref/Microsoft.AspNetCore.HeaderPropagation.netcoreapp3.0.cs

@@ -21,9 +21,9 @@ public readonly partial struct HeaderPropagationContext
     }
     public partial class HeaderPropagationEntry
     {
-        public HeaderPropagationEntry(string inboundHeaderName, string outboundHeaderName, System.Func<Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationContext, Microsoft.Extensions.Primitives.StringValues> valueFilter) { }
+        public HeaderPropagationEntry(string inboundHeaderName, string capturedHeaderName, System.Func<Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationContext, Microsoft.Extensions.Primitives.StringValues> valueFilter) { }
+        public string CapturedHeaderName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
         public string InboundHeaderName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
-        public string OutboundHeaderName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
         public System.Func<Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationContext, Microsoft.Extensions.Primitives.StringValues> ValueFilter { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
     }
     public sealed partial class HeaderPropagationEntryCollection : System.Collections.ObjectModel.Collection<Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationEntry>
@@ -36,9 +36,26 @@ public void Add(string inboundHeaderName, string outboundHeaderName, System.Func
     }
     public partial class HeaderPropagationMessageHandler : System.Net.Http.DelegatingHandler
     {
-        public HeaderPropagationMessageHandler(Microsoft.Extensions.Options.IOptions<Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationOptions> options, Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationValues values) { }
+        public HeaderPropagationMessageHandler(Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationMessageHandlerOptions options, Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationValues values) { }
         protected override System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> SendAsync(System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) { throw null; }
     }
+    public partial class HeaderPropagationMessageHandlerEntry
+    {
+        public HeaderPropagationMessageHandlerEntry(string capturedHeaderName, string outboundHeaderName) { }
+        public string CapturedHeaderName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
+        public string OutboundHeaderName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
+    }
+    public sealed partial class HeaderPropagationMessageHandlerEntryCollection : System.Collections.ObjectModel.Collection<Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationMessageHandlerEntry>
+    {
+        public HeaderPropagationMessageHandlerEntryCollection() { }
+        public void Add(string headerName) { }
+        public void Add(string capturedHeaderName, string outboundHeaderName) { }
+    }
+    public partial class HeaderPropagationMessageHandlerOptions
+    {
+        public HeaderPropagationMessageHandlerOptions() { }
+        public Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationMessageHandlerEntryCollection Headers { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
+    }
     public partial class HeaderPropagationMiddleware
     {
         public HeaderPropagationMiddleware(Microsoft.AspNetCore.Http.RequestDelegate next, Microsoft.Extensions.Options.IOptions<Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationOptions> options, Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationValues values) { }
@@ -60,6 +77,7 @@ namespace Microsoft.Extensions.DependencyInjection
     public static partial class HeaderPropagationHttpClientBuilderExtensions
     {
         public static Microsoft.Extensions.DependencyInjection.IHttpClientBuilder AddHeaderPropagation(this Microsoft.Extensions.DependencyInjection.IHttpClientBuilder builder) { throw null; }
+        public static Microsoft.Extensions.DependencyInjection.IHttpClientBuilder AddHeaderPropagation(this Microsoft.Extensions.DependencyInjection.IHttpClientBuilder builder, System.Action<Microsoft.AspNetCore.HeaderPropagation.HeaderPropagationMessageHandlerOptions> configure) { throw null; }
     }
     public static partial class HeaderPropagationServiceCollectionExtensions
     {

src/Middleware/HeaderPropagation/samples/HeaderPropagationSample/HeaderPropagationSample.csproj

@@ -8,6 +8,7 @@
     <Reference Include="Microsoft.AspNetCore.Diagnostics" />
     <Reference Include="Microsoft.AspNetCore.HeaderPropagation" />
     <Reference Include="Microsoft.AspNetCore.Hosting" />
+    <Reference Include="Microsoft.AspNetCore.Server.Kestrel" />
     <Reference Include="Microsoft.AspNetCore.StaticFiles" />
     <Reference Include="Microsoft.Extensions.Hosting" />
   </ItemGroup>

src/Middleware/HeaderPropagation/samples/HeaderPropagationSample/Program.cs

@@ -15,6 +15,7 @@ public static IHostBuilder CreateHostBuilder(string[] args) =>
             Host.CreateDefaultBuilder(args)
                 .ConfigureWebHost(webBuilder =>
                 {
+                    webBuilder.UseKestrel();
                     webBuilder.UseStartup<Startup>();
                 });
     }

src/Middleware/HeaderPropagation/samples/HeaderPropagationSample/Startup.cs

@@ -49,6 +49,9 @@ public void ConfigureServices(IServiceCollection services)
                 .AddHttpClient("test")
                 .AddHeaderPropagation();
 
+            services
+                .AddHttpClient("another")
+                .AddHeaderPropagation(options => options.Headers.Add("X-BetaFeatures", "X-Experiments"));
         }
 
         public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IHttpClientFactory clientFactory)
@@ -71,19 +74,23 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IHttpCli
                         await context.Response.WriteAsync($"'/' Got Header '{header.Key}': {string.Join(", ", header.Value)}\r\n");
                     }
 
-                    await context.Response.WriteAsync("Sending request to /forwarded\r\n");
+                    var clientNames = new[] { "test", "another" };
+                    foreach (var clientName in clientNames)
+                    {
+                        await context.Response.WriteAsync("Sending request to /forwarded\r\n");
 
-                    var uri = UriHelper.BuildAbsolute(context.Request.Scheme, context.Request.Host, context.Request.PathBase, "/forwarded");
-                    var client = clientFactory.CreateClient("test");
-                    var response = await client.GetAsync(uri);
+                        var uri = UriHelper.BuildAbsolute(context.Request.Scheme, context.Request.Host, context.Request.PathBase, "/forwarded");
+                        var client = clientFactory.CreateClient(clientName);
+                        var response = await client.GetAsync(uri);
 
-                    foreach (var header in response.RequestMessage.Headers)
-                    {
-                        await context.Response.WriteAsync($"Sent Header '{header.Key}': {string.Join(", ", header.Value)}\r\n");
-                    }
+                        foreach (var header in response.RequestMessage.Headers)
+                        {
+                            await context.Response.WriteAsync($"Sent Header '{header.Key}': {string.Join(", ", header.Value)}\r\n");
+                        }
 
-                    await context.Response.WriteAsync("Got response\r\n");
-                    await context.Response.WriteAsync(await response.Content.ReadAsStringAsync());
+                        await context.Response.WriteAsync("Got response\r\n");
+                        await context.Response.WriteAsync(await response.Content.ReadAsStringAsync());
+                    }
                 });
 
                 endpoints.MapGet("/forwarded", async context =>

src/Middleware/HeaderPropagation/src/DependencyInjection/HeaderPropagationHttpClientBuilderExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using Microsoft.AspNetCore.HeaderPropagation;
+using Microsoft.Extensions.Options;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
@@ -11,6 +12,9 @@ public static class HeaderPropagationHttpClientBuilderExtensions
         /// <summary>
         /// Adds a message handler for propagating headers collected by the <see cref="HeaderPropagationMiddleware"/> to a outgoing request.
         /// </summary>
+        /// <remarks>
+        /// When using this method, all the configured headers will be applied to the outgoing HTTP requests.
+        /// </remarks>
         /// <param name="builder">The <see cref="IHttpClientBuilder"/> to add the message handler to.</param>
         /// <returns>The <see cref="IHttpClientBuilder"/> so that additional calls can be chained.</returns>
         public static IHttpClientBuilder AddHeaderPropagation(this IHttpClientBuilder builder)
@@ -22,7 +26,49 @@ public static IHttpClientBuilder AddHeaderPropagation(this IHttpClientBuilder bu
 
             builder.Services.AddHeaderPropagation();
 
-            builder.AddHttpMessageHandler<HeaderPropagationMessageHandler>();
+            builder.AddHttpMessageHandler(services =>
+            {
+                var options = new HeaderPropagationMessageHandlerOptions();
+                var middlewareOptions = services.GetRequiredService<IOptions<HeaderPropagationOptions>>();
+                for (var i = 0; i < middlewareOptions.Value.Headers.Count; i++)
+                {
+                    var header = middlewareOptions.Value.Headers[i];
+                    options.Headers.Add(header.CapturedHeaderName, header.CapturedHeaderName);
+                }
+                return new HeaderPropagationMessageHandler(options, services.GetRequiredService<HeaderPropagationValues>());
+            });
+
+            return builder;
+        }
+
+        /// <summary>
+        /// Adds a message handler for propagating headers collected by the <see cref="HeaderPropagationMiddleware"/> to a outgoing request,
+        /// explicitly specifying which headers to propagate.
+        /// </summary>
+        /// <remarks>This also allows to redefine the name to use for a header in the outgoing request.</remarks>
+        /// <param name="builder">The <see cref="IHttpClientBuilder"/> to add the message handler to.</param>
+        /// <param name="configure">A delegate used to configure the <see cref="HeaderPropagationMessageHandlerOptions"/>.</param>
+        /// <returns>The <see cref="IHttpClientBuilder"/> so that additional calls can be chained.</returns>
+        public static IHttpClientBuilder AddHeaderPropagation(this IHttpClientBuilder builder, Action<HeaderPropagationMessageHandlerOptions> configure)
+        {
+            if (builder == null)
+            {
+                throw new ArgumentNullException(nameof(builder));
+            }
+
+            if (configure == null)
+            {
+                throw new ArgumentNullException(nameof(configure));
+            }
+
+            builder.Services.AddHeaderPropagation();
+
+            builder.AddHttpMessageHandler(services =>
+            {
+                var options = new HeaderPropagationMessageHandlerOptions();
+                configure(options);
+                return new HeaderPropagationMessageHandler(options, services.GetRequiredService<HeaderPropagationValues>());
+            });
 
             return builder;
         }

src/Middleware/HeaderPropagation/src/HeaderPropagationEntry.cs

@@ -13,34 +13,34 @@ public class HeaderPropagationEntry
     {
         /// <summary>
         /// Creates a new <see cref="HeaderPropagationEntry"/> with the provided <paramref name="inboundHeaderName"/>,
-        /// <paramref name="outboundHeaderName"/>, and 
+        /// <paramref name="capturedHeaderName"/> and <paramref name="valueFilter"/>.
         /// </summary>
         /// <param name="inboundHeaderName">
         /// The name of the header to be captured by <see cref="HeaderPropagationMiddleware"/>.
         /// </param>
-        ///  <param name="outboundHeaderName">
+        ///  <param name="capturedHeaderName">
         /// The name of the header to be added by <see cref="HeaderPropagationMessageHandler"/>.
         /// </param>
         /// <param name="valueFilter">
         /// A filter delegate that can be used to transform the header value. May be null.
         /// </param>
         public HeaderPropagationEntry(
             string inboundHeaderName,
-            string outboundHeaderName,
+            string capturedHeaderName,
             Func<HeaderPropagationContext, StringValues> valueFilter)
         {
             if (inboundHeaderName == null)
             {
                 throw new ArgumentNullException(nameof(inboundHeaderName));
             }
 
-            if (outboundHeaderName == null)
+            if (capturedHeaderName == null)
             {
-                throw new ArgumentNullException(nameof(outboundHeaderName));
+                throw new ArgumentNullException(nameof(capturedHeaderName));
             }
 
             InboundHeaderName = inboundHeaderName;
-            OutboundHeaderName = outboundHeaderName;
+            CapturedHeaderName = capturedHeaderName;
             ValueFilter = valueFilter; // May be null
         }
 
@@ -50,10 +50,10 @@ public HeaderPropagationEntry(
         public string InboundHeaderName { get; }
 
         /// <summary>
-        /// Gets the name of the header to be used by the <see cref="HeaderPropagationMessageHandler"/> for the
+        /// Gets the name of the header to be used by default by the <see cref="HeaderPropagationMessageHandler"/> for the
         /// outbound http requests.
         /// </summary>
-        public string OutboundHeaderName { get; }
+        public string CapturedHeaderName { get; }
 
         /// <summary>
         /// Gets or sets a filter delegate that can be used to transform the header value.

src/Middleware/HeaderPropagation/src/HeaderPropagationEntryCollection.cs

@@ -15,7 +15,7 @@ public sealed class HeaderPropagationEntryCollection : Collection<HeaderPropagat
         /// <summary>
         /// Adds an <see cref="HeaderPropagationEntry"/> that will use <paramref name="headerName"/> as
         /// the value of <see cref="HeaderPropagationEntry.InboundHeaderName"/> and
-        /// <see cref="HeaderPropagationEntry.OutboundHeaderName"/>.
+        /// <see cref="HeaderPropagationEntry.CapturedHeaderName"/>.
         /// </summary>
         /// <param name="headerName">The header name to be propagated.</param>
         public void Add(string headerName)
@@ -31,7 +31,7 @@ public void Add(string headerName)
         /// <summary>
         /// Adds an <see cref="HeaderPropagationEntry"/> that will use <paramref name="headerName"/> as
         /// the value of <see cref="HeaderPropagationEntry.InboundHeaderName"/> and
-        /// <see cref="HeaderPropagationEntry.OutboundHeaderName"/>.
+        /// <see cref="HeaderPropagationEntry.CapturedHeaderName"/>.
         /// </summary>
         /// <param name="headerName">The header name to be propagated.</param>
         /// <param name="valueFilter">

src/Middleware/HeaderPropagation/src/HeaderPropagationMessageHandler.cs

@@ -6,7 +6,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
-using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNetCore.HeaderPropagation
@@ -17,23 +16,17 @@ namespace Microsoft.AspNetCore.HeaderPropagation
     public class HeaderPropagationMessageHandler : DelegatingHandler
     {
         private readonly HeaderPropagationValues _values;
-        private readonly HeaderPropagationOptions _options;
+        private readonly HeaderPropagationMessageHandlerOptions _options;
 
         /// <summary>
         /// Creates a new instance of the <see cref="HeaderPropagationMessageHandler"/>.
         /// </summary>
         /// <param name="options">The options that define which headers are propagated.</param>
         /// <param name="values">The values of the headers to be propagated populated by the
         /// <see cref="HeaderPropagationMiddleware"/>.</param>
-        public HeaderPropagationMessageHandler(IOptions<HeaderPropagationOptions> options, HeaderPropagationValues values)
+        public HeaderPropagationMessageHandler(HeaderPropagationMessageHandlerOptions options, HeaderPropagationValues values)
         {
-            if (options == null)
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
-
-            _options = options.Value;
-
+            _options = options ?? throw new ArgumentNullException(nameof(options));
             _values = values ?? throw new ArgumentNullException(nameof(values));
         }
 
@@ -71,7 +64,7 @@ protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage reques
                 if (!request.Headers.TryGetValues(entry.OutboundHeaderName, out var _) &&
                     !(hasContent && request.Content.Headers.TryGetValues(entry.OutboundHeaderName, out var _)))
                 {
-                    if (captured.TryGetValue(entry.OutboundHeaderName, out var stringValues) &&
+                    if (captured.TryGetValue(entry.CapturedHeaderName, out var stringValues) &&
                         !StringValues.IsNullOrEmpty(stringValues))
                     {
                         if (stringValues.Count == 1)

src/Middleware/HeaderPropagation/src/HeaderPropagationMessageHandlerEntry.cs

@@ -0,0 +1,51 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNetCore.HeaderPropagation
+{
+    /// <summary>
+    /// Define the configuration of an header for the <see cref="HeaderPropagationMessageHandler"/>.
+    /// </summary>
+    public class HeaderPropagationMessageHandlerEntry
+    {
+        /// <summary>
+        /// Creates a new <see cref="HeaderPropagationMessageHandlerEntry"/> with the provided <paramref name="capturedHeaderName"/>
+        /// and <paramref name="outboundHeaderName"/>.
+        /// </summary>
+        /// <param name="capturedHeaderName">
+        /// The name of the header to be used to lookup the headers captured by the <see cref="HeaderPropagationMiddleware"/>.
+        /// </param>
+        /// <param name="outboundHeaderName">
+        /// The name of the header to be added to the outgoing http requests by the <see cref="HeaderPropagationMessageHandler"/>.
+        /// </param>
+        public HeaderPropagationMessageHandlerEntry(
+            string capturedHeaderName,
+            string outboundHeaderName)
+        {
+            if (capturedHeaderName == null)
+            {
+                throw new ArgumentNullException(nameof(capturedHeaderName));
+            }
+
+            if (outboundHeaderName == null)
+            {
+                throw new ArgumentNullException(nameof(outboundHeaderName));
+            }
+
+            CapturedHeaderName = capturedHeaderName;
+            OutboundHeaderName = outboundHeaderName;
+        }
+
+        /// <summary>
+        /// Gets the name of the header to be used to lookup the headers captured by the <see cref="HeaderPropagationMiddleware"/>.
+        /// </summary>
+        public string CapturedHeaderName { get; }
+
+        /// <summary>
+        /// Gets the name of the header to be added to the outgoing http requests by the <see cref="HeaderPropagationMessageHandler"/>.
+        /// </summary>
+        public string OutboundHeaderName { get; }
+    }
+}