Allow for using query strings in DefaultProbingRequestFactory. (#2421)

* Introduce a Query field on ActiveHealthCheckConfig. If provided, Query is appended to the probing request.

* <3 unit tests. Fix assignment in configurationconfigprovider.

* Add a test for a path with an embedded query string

* Mention the Query property in docs

---------

Co-authored-by: Robbie Knuth <jknuth@microsoft.com>
Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>

docs/docfx/articles/config-files.md

@@ -189,7 +189,8 @@ For additional fields see [ClusterConfig](xref:Yarp.ReverseProxy.Configuration.C
             "Interval": "00:00:10",
             "Timeout": "00:00:10",
             "Policy": "ConsecutiveFailures",
-            "Path": "/api/health" // API endpoint to query for health state
+            "Path": "/api/health", // API endpoint to query for health state
+            "Query": "?foo=bar"
           },
           "Passive": { // Disables destinations based on HTTP response codes
             "Enabled": true, // Defaults to false

docs/docfx/articles/dests-health-checks.md

@@ -16,7 +16,8 @@ There are several cluster-wide configuration settings controlling active health
             "Interval": "00:00:10",
             "Timeout": "00:00:10",
             "Policy": "ConsecutiveFailures",
-            "Path": "/api/health"
+            "Path": "/api/health",
+            "Query": "?foo=bar",
           }
         },
         "Metadata": {
@@ -49,7 +50,8 @@ var clusters = new[]
                 Interval = TimeSpan.FromSeconds(10),
                 Timeout = TimeSpan.FromSeconds(10),
                 Policy = HealthCheckConstants.ActivePolicy.ConsecutiveFailures,
-                Path = "/api/health"
+                Path = "/api/health",
+                Query = "?foo=bar",
             }
         },
         Metadata = new Dictionary<string, string> { { ConsecutiveFailuresHealthPolicyOptions.ThresholdMetadataName, "5" } },
@@ -74,6 +76,7 @@ Active health check settings can also be defined in code via the corresponding t
 - `Timeout` - probing request timeout. Default `00:00:10`
 - `Policy` - name of a policy evaluating destinations' active health states. Mandatory parameter
 - `Path` -  health check path on all cluster's destinations. Default `null`.
+- `Query` -  health check query on all cluster's destinations. Default `null`.
 
 `Destination` section and [DestinationConfig](xref:Yarp.ReverseProxy.Configuration.DestinationConfig).
 

src/ReverseProxy/Configuration/ActiveHealthCheckConfig.cs

@@ -35,6 +35,11 @@ public sealed record ActiveHealthCheckConfig
     /// </summary>
     public string? Path { get; init; }
 
+    /// <summary>
+    /// Query string to append to the probe, including the leading '?'.
+    /// </summary>
+    public string? Query { get; init; }
+
     public bool Equals(ActiveHealthCheckConfig? other)
     {
         if (other is null)
@@ -46,7 +51,8 @@ public bool Equals(ActiveHealthCheckConfig? other)
             && Interval == other.Interval
             && Timeout == other.Timeout
             && string.Equals(Policy, other.Policy, StringComparison.OrdinalIgnoreCase)
-            && string.Equals(Path, other.Path, StringComparison.Ordinal);
+            && string.Equals(Path, other.Path, StringComparison.Ordinal)
+            && string.Equals(Query, other.Query, StringComparison.Ordinal);
     }
 
     public override int GetHashCode()
@@ -55,6 +61,7 @@ public override int GetHashCode()
             Interval,
             Timeout,
             Policy?.GetHashCode(StringComparison.OrdinalIgnoreCase),
-            Path?.GetHashCode(StringComparison.Ordinal));
+            Path?.GetHashCode(StringComparison.Ordinal),
+            Query?.GetHashCode(StringComparison.Ordinal));
     }
 }

src/ReverseProxy/Configuration/ConfigProvider/ConfigurationConfigProvider.cs

@@ -312,7 +312,8 @@ private static RouteQueryParameter CreateRouteQueryParameter(IConfigurationSecti
             Interval = section.ReadTimeSpan(nameof(ActiveHealthCheckConfig.Interval)),
             Timeout = section.ReadTimeSpan(nameof(ActiveHealthCheckConfig.Timeout)),
             Policy = section[nameof(ActiveHealthCheckConfig.Policy)],
-            Path = section[nameof(ActiveHealthCheckConfig.Path)]
+            Path = section[nameof(ActiveHealthCheckConfig.Path)],
+            Query = section[nameof(ActiveHealthCheckConfig.Query)]
         };
     }
 

src/ReverseProxy/Health/DefaultProbingRequestFactory.cs

@@ -4,6 +4,7 @@
 using System.Net;
 using System.Net.Http;
 using System.Reflection;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.Net.Http.Headers;
 using Yarp.ReverseProxy.Model;
@@ -20,7 +21,8 @@ public HttpRequestMessage CreateRequest(ClusterModel cluster, DestinationModel d
         var probeAddress = !string.IsNullOrEmpty(destination.Config.Health) ? destination.Config.Health : destination.Config.Address;
         var probePath = cluster.Config.HealthCheck?.Active?.Path;
         UriHelper.FromAbsolute(probeAddress, out var destinationScheme, out var destinationHost, out var destinationPathBase, out _, out _);
-        var probeUri = UriHelper.BuildAbsolute(destinationScheme, destinationHost, destinationPathBase, probePath, default);
+        var query = QueryString.FromUriComponent(cluster.Config.HealthCheck?.Active?.Query ?? "");
+        var probeUri = UriHelper.BuildAbsolute(destinationScheme, destinationHost, destinationPathBase, probePath, query);
 
         var request = new HttpRequestMessage(HttpMethod.Get, probeUri)
         {

test/ReverseProxy.Tests/Configuration/ActiveHealthCheckConfigTests.cs

@@ -61,6 +61,24 @@ public void Equals_Different_Value_Returns_False()
         Assert.False(equals);
     }
 
+    [Fact]
+    public void Equals_DifferingQueries_Returns_False()
+    {
+        var options1 = new ActiveHealthCheckConfig
+        {
+            Query = "?key=value1"
+        };
+
+        var options2 = new ActiveHealthCheckConfig
+        {
+            Query = "?key=value2"
+        };
+
+        var equals = options1.Equals(options2);
+
+        Assert.False(equals);
+    }
+
     [Fact]
     public void Equals_Second_Null_Returns_False()
     {

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

@@ -69,7 +69,8 @@ public class ConfigurationConfigProviderTests
                             Interval = TimeSpan.FromSeconds(4),
                             Timeout = TimeSpan.FromSeconds(6),
                             Policy = "Any5xxResponse",
-                            Path = "healthCheckPath"
+                            Path = "healthCheckPath",
+                            Query = "?key=value"
                         },
                         AvailableDestinationsPolicy = "HealthyOrPanic"
                     },
@@ -239,7 +240,8 @@ public class ConfigurationConfigProviderTests
                     ""Interval"": ""00:00:04"",
                     ""Timeout"": ""00:00:06"",
                     ""Policy"": ""Any5xxResponse"",
-                    ""Path"": ""healthCheckPath""
+                    ""Path"": ""healthCheckPath"",
+                    ""Query"": ""?key=value""
                 },
                 ""AvailableDestinationsPolicy"": ""HealthyOrPanic""
             },
@@ -540,6 +542,7 @@ private void VerifyValidAbstractConfig(IProxyConfig validConfig, IProxyConfig ab
         Assert.Equal(cluster1.HealthCheck.Active.Timeout, abstractCluster1.HealthCheck.Active.Timeout);
         Assert.Equal(cluster1.HealthCheck.Active.Policy, abstractCluster1.HealthCheck.Active.Policy);
         Assert.Equal(cluster1.HealthCheck.Active.Path, abstractCluster1.HealthCheck.Active.Path);
+        Assert.Equal(cluster1.HealthCheck.Active.Query, abstractCluster1.HealthCheck.Active.Query);
         Assert.Equal(LoadBalancingPolicies.Random, abstractCluster1.LoadBalancingPolicy);
         Assert.Equal(cluster1.SessionAffinity.Enabled, abstractCluster1.SessionAffinity.Enabled);
         Assert.Equal(cluster1.SessionAffinity.FailurePolicy, abstractCluster1.SessionAffinity.FailurePolicy);

test/ReverseProxy.Tests/Health/DefaultProbingRequestFactoryTests.cs

@@ -14,20 +14,28 @@ namespace Yarp.ReverseProxy.Health.Tests;
 public class DefaultProbingRequestFactoryTests
 {
     [Theory]
-    [InlineData("https://localhost:10000/", null, null, "https://localhost:10000/")]
-    [InlineData("https://localhost:10000/", "https://localhost:20000/", null, "https://localhost:20000/")]
-    [InlineData("https://localhost:10000/", null, "/api/health/", "https://localhost:10000/api/health/")]
-    [InlineData("https://localhost:10000/", "https://localhost:20000/", "/api/health/", "https://localhost:20000/api/health/")]
-    [InlineData("https://localhost:10000/api", "https://localhost:20000/", "/health/", "https://localhost:20000/health/")]
-    [InlineData("https://localhost:10000/", "https://localhost:20000/api", "/health/", "https://localhost:20000/api/health/")]
-    public void CreateRequest_HealthEndpointIsNotDefined_UseDestinationAddress(string address, string health, string healthPath, string expectedRequestUri)
+    [InlineData("https://localhost:10000/", null, null, null, "https://localhost:10000/")]
+    [InlineData("https://localhost:10000/", "https://localhost:20000/", null, null, "https://localhost:20000/")]
+    [InlineData("https://localhost:10000/", null, "/api/health/", null, "https://localhost:10000/api/health/")]
+    [InlineData("https://localhost:10000/", "https://localhost:20000/", "/api/health/", null, "https://localhost:20000/api/health/")]
+    [InlineData("https://localhost:10000/api", "https://localhost:20000/", "/health/", null, "https://localhost:20000/health/")]
+    [InlineData("https://localhost:10000/", "https://localhost:20000/api", "/health/", null, "https://localhost:20000/api/health/")]
+    [InlineData("https://localhost:10000/", null, null, "?key=value", "https://localhost:10000/?key=value")]
+    [InlineData("https://localhost:10000/", "https://localhost:20000/", null, "?key=value", "https://localhost:20000/?key=value")]
+    [InlineData("https://localhost:10000/", null, "/api/health/", "?key=value", "https://localhost:10000/api/health/?key=value")]
+    [InlineData("https://localhost:10000/", "https://localhost:20000/", "/api/health/", "?key=value", "https://localhost:20000/api/health/?key=value")]
+    [InlineData("https://localhost:10000/api", "https://localhost:20000/", "/health/", "?key=value", "https://localhost:20000/health/?key=value")]
+    [InlineData("https://localhost:10000/", "https://localhost:20000/api", "/health/", "?key=value", "https://localhost:20000/api/health/?key=value")]
+    [InlineData("https://localhost:10000/", "https://localhost:20000/api", "/health?foo=bar", "?key=value", "https://localhost:20000/api/health%3Ffoo=bar?key=value")]
+    public void CreateRequest_HealthEndpointIsNotDefined_UseDestinationAddress(string address, string health, string healthPath, string query, string expectedRequestUri)
     {
         var clusterModel = GetClusterConfig("cluster0",
             new ActiveHealthCheckConfig()
             {
                 Enabled = true,
                 Policy = "policy",
                 Path = healthPath,
+                Query = query,
             }, HttpVersion.Version20);
         var destinationModel = new DestinationModel(new DestinationConfig { Address = address, Health = health });
         var factory = new DefaultProbingRequestFactory();