Make the config object model read-only

Directory.Build.props

@@ -6,6 +6,7 @@
     <Copyright>© Microsoft Corporation. All rights reserved.</Copyright>
     <PackageIcon></PackageIcon>
     <PackageIconFullPath></PackageIconFullPath>
+    <LangVersion>9.0</LangVersion>
   </PropertyGroup>
   <PropertyGroup>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
@@ -16,4 +17,4 @@
   <PropertyGroup>
     <MoqPublicKey>0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7</MoqPublicKey>
   </PropertyGroup>
-</Project>
+</Project>

docs/docfx/articles/configproviders.md

@@ -124,7 +124,7 @@ public void ConfigureServices(IServiceCollection services)
         {
             RouteId = "route1",
             ClusterId = "cluster1",
-            Match =
+            Match = new ProxyMatch
             {
                 Path = "{**catch-all}"
             }
@@ -135,7 +135,7 @@ public void ConfigureServices(IServiceCollection services)
         new Cluster()
         {
             Id = "cluster1",
-            Destinations =
+            Destinations = new Dictionary<string, Destination>(StringComparer.OrdinalIgnoreCase)
             {
                 { "destination1", new Destination() { Address = "https://example.com" } }
             }

docs/docfx/articles/direct-proxying.md

@@ -54,7 +54,7 @@ public void Configure(IApplicationBuilder app, IHttpProxy httpProxy)
         UseCookies = false
     });
     var transformer = new CustomTransformer(); // or HttpTransformer.Default;
-    var requestOptions = new RequestProxyOptions(TimeSpan.FromSeconds(100), null);
+    var requestOptions = new RequestProxyOptions { Timeout = TimeSpan.FromSeconds(100) };
 
     app.UseRouting();
     app.UseAuthorization();

docs/docfx/articles/header-routing.md

@@ -90,7 +90,7 @@ Code:
         {
             RouteId = "route1",
             ClusterId = "cluster1",
-            Match =
+            Match = new ProxyMatch
             {
                 Path = "{**catch-all}",
                 Headers = new[]
@@ -108,7 +108,7 @@ Code:
         {
             RouteId = "route2",
             ClusterId = "cluster1",
-            Match =
+            Match = new ProxyMatch
             {
                 Path = "{**catch-all}",
                 Headers = new[]
@@ -126,7 +126,7 @@ Code:
         {
             RouteId = "route3",
             ClusterId = "cluster1",
-            Match =
+            Match = new ProxyMatch
             {
                 Path = "{**catch-all}",
                 Headers = new[]
@@ -143,7 +143,7 @@ Code:
         {
             RouteId = "route4",
             ClusterId = "cluster1",
-            Match =
+            Match = new ProxyMatch
             {
                 Path = "{**catch-all}",
                 Headers = new[]

docs/docfx/articles/load-balancing.md

@@ -50,7 +50,7 @@ var clusters = new[]
     {
         Id = "cluster1",
         LoadBalancingPolicy = LoadBalancingPolicies.RoundRobin,
-        Destinations =
+        Destinations = new Dictionary<string, Destination>(StringComparer.OrdinalIgnoreCase)
         {
             { "destination1", new Destination() { Address = "https://localhost:10000" } },
             { "destination2", new Destination() { Address = "https://localhost:10010" } }

samples/ReverseProxy.Code.Sample/Startup.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using System;
+using System.Collections.Generic;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -37,7 +39,7 @@ public void ConfigureServices(IServiceCollection services)
                 {
                     RouteId = "route1",
                     ClusterId = "cluster1",
-                    Match =
+                    Match = new ProxyMatch
                     {
                         Path = "{**catch-all}"
                     }
@@ -49,16 +51,15 @@ public void ConfigureServices(IServiceCollection services)
                 {
                     Id = "cluster1",
                     SessionAffinity = new SessionAffinityOptions { Enabled = true, Mode = "Cookie" },
-                    Destinations =
+                    Destinations = new Dictionary<string, Destination>(StringComparer.OrdinalIgnoreCase)
                     {
                         { "destination1", new Destination() { Address = "https://localhost:10000" } }
                     }
                 }
             };
 
             services.AddReverseProxy()
-                .LoadFromMemory(routes, clusters)
-                .AddProxyConfigFilter<CustomConfigFilter>();
+                .LoadFromMemory(routes, clusters);
 
             services.AddHttpContextAccessor();
             services.AddSingleton<IProxyMetricsConsumer, ProxyMetricsConsumer>();

samples/ReverseProxy.Config.Sample/CustomConfigFilter.cs

@@ -12,39 +12,57 @@ namespace Microsoft.ReverseProxy.Sample
 {
     public class CustomConfigFilter : IProxyConfigFilter
     {
-        public Task ConfigureClusterAsync(Cluster cluster, CancellationToken cancel)
+        public ValueTask<Cluster> ConfigureClusterAsync(Cluster cluster, CancellationToken cancel)
         {
             // How to use custom metadata to configure clusters
             if (cluster.Metadata?.TryGetValue("CustomHealth", out var customHealth) ?? false
                 && string.Equals(customHealth, "true", StringComparison.OrdinalIgnoreCase))
             {
-                cluster.HealthCheck ??= new HealthCheckOptions { Active = new ActiveHealthCheckOptions() };
-                cluster.HealthCheck.Active.Enabled = true;
-                cluster.HealthCheck.Active.Policy = HealthCheckConstants.ActivePolicy.ConsecutiveFailures;
+                cluster = cluster with
+                {
+                    HealthCheck = new HealthCheckOptions
+                    {
+                        Active = new ActiveHealthCheckOptions
+                        {
+                            Enabled = true,
+                            Policy = HealthCheckConstants.ActivePolicy.ConsecutiveFailures,
+                        },
+                        Passive = cluster.HealthCheck?.Passive,
+                    }
+                };
             }
 
             // Or wrap the meatadata in config sugar
             var config = new ConfigurationBuilder().AddInMemoryCollection(cluster.Metadata).Build();
             if (config.GetValue<bool>("CustomHealth"))
             {
-                cluster.HealthCheck ??= new HealthCheckOptions { Active = new ActiveHealthCheckOptions() };
-                cluster.HealthCheck.Active.Enabled = true;
-                cluster.HealthCheck.Active.Policy = HealthCheckConstants.ActivePolicy.ConsecutiveFailures;
+                cluster = cluster with
+                {
+                    HealthCheck = new HealthCheckOptions
+                    {
+                        Active = new ActiveHealthCheckOptions
+                        {
+                            Enabled = true,
+                            Policy = HealthCheckConstants.ActivePolicy.ConsecutiveFailures,
+                        },
+                        Passive = cluster.HealthCheck?.Passive,
+                    }
+                };
             }
 
-            return Task.CompletedTask;
+            return new ValueTask<Cluster>(cluster);
         }
 
-        public Task ConfigureRouteAsync(ProxyRoute route, CancellationToken cancel)
+        public ValueTask<ProxyRoute> ConfigureRouteAsync(ProxyRoute route, CancellationToken cancel)
         {
             // Do not let config based routes take priority over code based routes.
             // Lower numbers are higher priority. Code routes default to 0.
             if (route.Order.HasValue && route.Order.Value < 1)
             {
-                route.Order = 1;
+                return new ValueTask<ProxyRoute>(route with { Order = 1 });
             }
 
-            return Task.CompletedTask;
+            return new ValueTask<ProxyRoute>(route);
         }
     }
 }

samples/ReverseProxy.Direct.Sample/Startup.cs

@@ -41,7 +41,7 @@ public void Configure(IApplicationBuilder app, IHttpProxy httpProxy)
 
             // Copy all request headers except Host
             var transformer = new CustomTransformer(); // or HttpTransformer.Default;
-            var requestOptions = new RequestProxyOptions(TimeSpan.FromSeconds(100), null);
+            var requestOptions = new RequestProxyOptions { Timeout = TimeSpan.FromSeconds(100) };
 
             app.UseRouting();
             app.UseAuthorization();

src/ReverseProxy.ServiceFabric/ServiceDiscovery/Discoverer.cs

@@ -105,8 +105,8 @@ public Discoverer(
                             continue;
                         }
 
-                        var cluster = LabelsParser.BuildCluster(service.ServiceName, serviceExtensionLabels);
-                        await DiscoverDestinationsAsync(cluster, options, service, serviceExtensionLabels, cancellation);
+                        var destinations = await DiscoverDestinationsAsync(options, service, serviceExtensionLabels, cancellation);
+                        var cluster = LabelsParser.BuildCluster(service.ServiceName, serviceExtensionLabels, destinations);
                         var clusterValidationErrors = await _configValidator.ValidateClusterAsync(cluster);
                         if (clusterValidationErrors.Count > 0)
                         {
@@ -242,8 +242,7 @@ private bool HttpsSchemeSelector(string urlScheme)
         /// and populates the specified <paramref name="cluster"/>'s <see cref="Cluster.Destinations"/> accordingly.
         /// </summary>
         /// <remarks>All non-fatal exceptions are caught and logged.</remarks>
-        private async Task DiscoverDestinationsAsync(
-            Cluster cluster,
+        private async Task<IReadOnlyDictionary<string, Destination>> DiscoverDestinationsAsync(
             ServiceFabricDiscoveryOptions options,
             ServiceWrapper service,
             Dictionary<string, string> serviceExtensionLabels,
@@ -257,9 +256,11 @@ private async Task DiscoverDestinationsAsync(
             catch (Exception ex) // TODO: davidni: not fatal?
             {
                 Log.GettingPartitionFailed(_logger, service.ServiceName, ex);
-                return;
+                return null;
             }
 
+            var destinations = new Dictionary<string, Destination>(StringComparer.OrdinalIgnoreCase);
+
             var listenerName = serviceExtensionLabels.GetValueOrDefault("YARP.Backend.ServiceFabric.ListenerName", string.Empty);
             var healthListenerName = serviceExtensionLabels.GetValueOrDefault("YARP.Backend.HealthCheck.Active.ServiceFabric.ListenerName", string.Empty);
             var statefulReplicaSelectionMode = ParseStatefulReplicaSelectionMode(serviceExtensionLabels, service.ServiceName);
@@ -297,9 +298,9 @@ private async Task DiscoverDestinationsAsync(
                         var destination = BuildDestination(replica, listenerName, healthListenerName);
 
                         ReportReplicaHealth(options, service, partition, replica, HealthState.Ok, $"Successfully built the endpoint from listener '{listenerName}'.");
-                        if (!cluster.Destinations.TryAdd(replica.Id.ToString(), destination))
+                        if (!destinations.TryAdd(replica.Id.ToString(), destination))
                         {
-                            throw new ConfigException($"Duplicated endpoint id '{replica.Id}'. Skipping repeated definition, service '{service.ServiceName}', backend id '{cluster.Id}'");
+                            throw new ConfigException($"Duplicated endpoint id '{replica.Id}'. Skipping repeated definition for service '{service.ServiceName}'.");
                         }
                     }
                     catch (ConfigException ex)
@@ -319,6 +320,8 @@ private async Task DiscoverDestinationsAsync(
                     }
                 }
             }
+
+            return destinations;
         }
 
         private StatefulReplicaSelectionMode ParseStatefulReplicaSelectionMode(Dictionary<string, string> serviceExtensionLabels, Uri serviceName)