add OutputCachePolicy support

docs/docfx/articles/output-caching.md

@@ -0,0 +1,63 @@
+# Output Caching
+
+## Introduction
+The reverse proxy can be used to cache proxied responses and serve requests before they are proxied to the destination servers. This can reduce load on the destination servers, add a layer of protection, and ensure consistent policies are implemented across your applications.
+
+> This feature is only available when using .NET 7.0 or later
+
+## Defaults
+
+No output caching is performed unless enabled in the route or application configuration.
+
+## Configuration
+Output Cache policies can be specified per route via [RouteConfig.OutputCachePolicy](xref:Yarp.ReverseProxy.Configuration.RouteConfig) and can be bound from the `Routes` sections of the config file. As with other route properties, this can be modified and reloaded without restarting the proxy. Policy names are case insensitive.
+
+Example:
+```JSON
+{
+  "ReverseProxy": {
+    "Routes": {
+      "route1" : {
+        "ClusterId": "cluster1",
+        "OutputCachePolicy": "customPolicy",
+        "Match": {
+          "Hosts": [ "localhost" ]
+        }
+      }
+    },
+    "Clusters": {
+      "cluster1": {
+        "Destinations": {
+          "cluster1/destination1": {
+            "Address": "https://localhost:10001/"
+          }
+        }
+      }
+    }
+  }
+}
+```
+
+[Output cache policies](https://learn.microsoft.com/aspnet/core/performance/caching/output) are an ASP.NET Core concept that the proxy utilizes. The proxy provides the above configuration to specify a policy per route and the rest is handled by existing ASP.NET Core output caching middleware.
+
+Output cache policies can be configured in Program.cs as follows:
+```c#
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddOutputCache(options =>
+{
+    options.AddPolicy("customPolicy", builder => builder.Expire(TimeSpan.FromSeconds(20)));
+});
+```
+
+Then add the output caching middleware:
+
+```c#
+var app = builder.Build();
+
+app.UseOutputCache();
+
+app.MapReverseProxy();
+```
+
+See the [Output Caching](https://learn.microsoft.com/aspnet/core/performance/caching/output) docs for setting up your preferred kind of output caching.

docs/docfx/articles/toc.yml

@@ -24,6 +24,8 @@
   href: authn-authz.md
 - name: Rate Limiting
   href: rate-limiting.md
+- name: Output Caching
+  href: output-caching.md
 - name: Cross-Origin Requests (CORS)
   href: cors.md
 - name: Session Affinity

samples/KubernetesIngress.Sample/README.md

@@ -43,16 +43,17 @@ metadata:
   annotations:
     yarp.ingress.kubernetes.io/authorization-policy: authzpolicy
     yarp.ingress.kubernetes.io/rate-limiter-policy: ratelimiterpolicy
+    yarp.ingress.kubernetes.io/output-cache-policy: outputcachepolicy
     yarp.ingress.kubernetes.io/transforms: |
       - PathRemovePrefix: "/apis"
     yarp.ingress.kubernetes.io/route-headers: |
       - Name: the-header-key
-        Values: 
+        Values:
         - the-header-value
         Mode: Contains
         IsCaseSensitive: false
       - Name: another-header-key
-        Values: 
+        Values:
         - another-header-value
         Mode: Contains
         IsCaseSensitive: false
@@ -75,6 +76,7 @@ The table below lists the available annotations.
 |---|---|
 |yarp.ingress.kubernetes.io/authorization-policy|string|
 |yarp.ingress.kubernetes.io/rate-limiter-policy|string|
+|yarp.ingress.kubernetes.io/output-cache-policy|string|
 |yarp.ingress.kubernetes.io/backend-protocol|string|
 |yarp.ingress.kubernetes.io/cors-policy|string|
 |yarp.ingress.kubernetes.io/health-check|[ActivateHealthCheckConfig](https://microsoft.github.io/reverse-proxy/api/Yarp.ReverseProxy.Configuration.ActiveHealthCheckConfig.html)|
@@ -98,6 +100,10 @@ See https://microsoft.github.io/reverse-proxy/articles/rate-limiting.html for a
 
 `yarp.ingress.kubernetes.io/rate-limiter-policy: mypolicy`
 
+#### Output Cache Policy
+
+`yarp.ingress.kubernetes.io/output-cache-policy: mycachepolicy`
+
 #### Backend Protocol
 
 Specifies the protocol of the backend service. Defaults to http.
@@ -196,12 +202,12 @@ See https://microsoft.github.io/reverse-proxy/api/Yarp.ReverseProxy.Configuratio
 ```
 yarp.ingress.kubernetes.io/route-headers: |
   - Name: the-header-key
-    Values: 
+    Values:
     - the-header-value
     Mode: Contains
     IsCaseSensitive: false
   - Name: another-header-key
-    Values: 
+    Values:
     - another-header-value
     Mode: Contains
     IsCaseSensitive: false

src/Kubernetes.Controller/Converters/YarpIngressOptions.cs

@@ -14,6 +14,7 @@ internal sealed class YarpIngressOptions
     public string AuthorizationPolicy { get; set; }
 #if NET7_0_OR_GREATER
     public string RateLimiterPolicy { get; set; }
+    public string OutputCachePolicy { get; set; }
 #endif
     public SessionAffinityConfig SessionAffinity { get; set; }
     public HttpClientConfig HttpClientConfig { get; set; }

src/Kubernetes.Controller/Converters/YarpParser.cs

@@ -142,6 +142,7 @@ private static RouteConfig CreateRoute(YarpIngressContext ingressContext, V1HTTP
             AuthorizationPolicy = ingressContext.Options.AuthorizationPolicy,
 #if NET7_0_OR_GREATER
             RateLimiterPolicy = ingressContext.Options.RateLimiterPolicy,
+            OutputCachePolicy = ingressContext.Options.OutputCachePolicy,
 #endif
 #if NET8_0_OR_GREATER
             Timeout = ingressContext.Options.Timeout,
@@ -234,6 +235,20 @@ private static YarpIngressOptions HandleAnnotations(YarpIngressContext context,
         {
             options.RateLimiterPolicy = rateLimiterPolicy;
         }
+        if (annotations.TryGetValue("yarp.ingress.kubernetes.io/output-cache-policy", out var outputCachePolicy))
+        {
+            options.OutputCachePolicy = outputCachePolicy;
+        }
+#endif
+#if NET8_0_OR_GREATER
+        if (annotations.TryGetValue("yarp.ingress.kubernetes.io/timeout", out var timeout))
+        {
+            options.Timeout = TimeSpan.Parse(timeout, CultureInfo.InvariantCulture);
+        }
+        if (annotations.TryGetValue("yarp.ingress.kubernetes.io/timeout-policy", out var timeoutPolicy))
+        {
+            options.TimeoutPolicy = timeoutPolicy;
+        }
 #endif
         if (annotations.TryGetValue("yarp.ingress.kubernetes.io/cors-policy", out var corsPolicy))
         {

src/ReverseProxy/Configuration/ConfigProvider/ConfigurationConfigProvider.cs

@@ -149,6 +149,7 @@ private static RouteConfig CreateRoute(IConfigurationSection section)
             AuthorizationPolicy = section[nameof(RouteConfig.AuthorizationPolicy)],
 #if NET7_0_OR_GREATER
             RateLimiterPolicy = section[nameof(RouteConfig.RateLimiterPolicy)],
+            OutputCachePolicy = section[nameof(RouteConfig.OutputCachePolicy)],
 #endif
 #if NET8_0_OR_GREATER
             TimeoutPolicy = section[nameof(RouteConfig.TimeoutPolicy)],

src/ReverseProxy/Configuration/RouteConfig.cs

@@ -51,6 +51,12 @@ public sealed record RouteConfig
     /// Set to "Default" or leave empty to use the global rate limits, if any.
     /// </summary>
     public string? RateLimiterPolicy { get; init; }
+
+    /// <summary>
+    /// The name of the OutputCachePolicy to apply to this route.
+    /// If not set then only the BasePolicy will apply.
+    /// </summary>
+    public string? OutputCachePolicy { get; init; }
 #endif
 #if NET8_0_OR_GREATER
     /// <summary>
@@ -106,6 +112,7 @@ public bool Equals(RouteConfig? other)
             && string.Equals(AuthorizationPolicy, other.AuthorizationPolicy, StringComparison.OrdinalIgnoreCase)
 #if NET7_0_OR_GREATER
             && string.Equals(RateLimiterPolicy, other.RateLimiterPolicy, StringComparison.OrdinalIgnoreCase)
+            && string.Equals(OutputCachePolicy, other.OutputCachePolicy, StringComparison.OrdinalIgnoreCase)
 #endif
 #if NET8_0_OR_GREATER
             && string.Equals(TimeoutPolicy, other.TimeoutPolicy, StringComparison.OrdinalIgnoreCase)
@@ -127,6 +134,7 @@ public override int GetHashCode()
         hash.Add(AuthorizationPolicy?.GetHashCode(StringComparison.OrdinalIgnoreCase));
 #if NET7_0_OR_GREATER
         hash.Add(RateLimiterPolicy?.GetHashCode(StringComparison.OrdinalIgnoreCase));
+        hash.Add(OutputCachePolicy?.GetHashCode(StringComparison.OrdinalIgnoreCase));
 #endif
 #if NET8_0_OR_GREATER
         hash.Add(Timeout?.GetHashCode());

src/ReverseProxy/Routing/ProxyEndpointFactory.cs

@@ -14,6 +14,7 @@
 #endif
 #if NET7_0_OR_GREATER
 using Microsoft.AspNetCore.RateLimiting;
+using Microsoft.AspNetCore.OutputCaching;
 #endif
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Routing.Patterns;
@@ -137,6 +138,11 @@ public Endpoint CreateEndpoint(RouteModel route, IReadOnlyList<Action<EndpointBu
         {
             endpointBuilder.Metadata.Add(new EnableRateLimitingAttribute(config.RateLimiterPolicy));
         }
+
+        if (!string.IsNullOrEmpty(config.OutputCachePolicy))
+        {
+            endpointBuilder.Metadata.Add(new OutputCacheAttribute { PolicyName = config.OutputCachePolicy });
+        }
 #endif
 #if NET8_0_OR_GREATER
         if (string.Equals(TimeoutPolicyConstants.Disable, config.TimeoutPolicy, StringComparison.OrdinalIgnoreCase))

test/ReverseProxy.Tests/Configuration/ConfigProvider/ConfigurationConfigProviderTests.cs

@@ -347,6 +347,7 @@ public class ConfigurationConfigProviderTests
             ""ClusterId"": ""cluster1"",
             ""AuthorizationPolicy"": ""Default"",
             ""RateLimiterPolicy"": ""Default"",
+            ""OutputCachePolicy"": ""Default"",
             ""CorsPolicy"": ""Default"",
             ""TimeoutPolicy"": ""Default"",
             ""Timeout"": ""00:00:01"",
@@ -393,6 +394,7 @@ public class ConfigurationConfigProviderTests
             ""ClusterId"": ""cluster2"",
             ""AuthorizationPolicy"": null,
             ""RateLimiterPolicy"": null,
+            ""OutputCachePolicy"": null,
             ""CorsPolicy"": null,
             ""Metadata"": null,
             ""Transforms"": null