Add health endpoint to dashboard and call from app host (#9191)

Author: JamesNK

src/Aspire.Dashboard/DashboardEndpointsBuilder.cs

@@ -14,6 +14,11 @@ namespace Aspire.Dashboard;
 
 public static class DashboardEndpointsBuilder
 {
+    public static void MapDashboardHealthChecks(this IEndpointRouteBuilder endpoints)
+    {
+        endpoints.MapHealthChecks($"/{DashboardUrls.HealthBasePath}").AllowAnonymous();
+    }
+
     public static void MapDashboardApi(this IEndpointRouteBuilder endpoints, DashboardOptions dashboardOptions)
     {
         if (dashboardOptions.Frontend.AuthMode == FrontendAuthMode.BrowserToken)

src/Aspire.Dashboard/DashboardWebApplication.cs

@@ -204,6 +204,7 @@ public DashboardWebApplication(
             // See https://learn.microsoft.com/aspnet/core/performance/response-compression#compression-with-https for more information
             options.MimeTypes = ["text/javascript", "application/javascript", "text/css", "image/svg+xml"];
         });
+        builder.Services.AddHealthChecks();
         if (dashboardOptions.Otlp.Cors.IsCorsEnabled)
         {
             builder.Services.AddCors(options =>
@@ -441,6 +442,7 @@ public DashboardWebApplication(
         _app.MapGrpcService<OtlpGrpcLogsService>();
 
         _app.MapDashboardApi(dashboardOptions);
+        _app.MapDashboardHealthChecks();
     }
 
     private ILogger<DashboardWebApplication> GetLogger()

src/Aspire.Dashboard/Utils/DashboardUrls.cs

@@ -14,6 +14,7 @@ internal static class DashboardUrls
     public const string StructuredLogsBasePath = "structuredlogs";
     public const string TracesBasePath = "traces";
     public const string LoginBasePath = "login";
+    public const string HealthBasePath = "health";
 
     public static string ResourcesUrl(string? resource = null, string? view = null, string? hiddenTypes = null, string? hiddenStates = null, string? hiddenHealthStates = null)
     {

src/Aspire.Hosting/Dashboard/DashboardLifecycleHook.cs

@@ -179,7 +179,7 @@ private void ConfigureAspireDashboardResource(IResource dashboardResource)
         dashboardResource.Annotations.Add(new ResourceSnapshotAnnotation(snapshot));
 
         dashboardResource.Annotations.Add(new EnvironmentCallbackAnnotation(ConfigureEnvironmentVariables));
-        dashboardResource.Annotations.Add(new HealthCheckAnnotation(KnownHealthCheckNames.DasboardHealthCheck));
+        dashboardResource.Annotations.Add(new HealthCheckAnnotation(KnownHealthCheckNames.DashboardHealthCheck));
     }
 
     internal async Task ConfigureEnvironmentVariables(EnvironmentCallbackContext context)

src/Aspire.Hosting/DistributedApplicationBuilder.cs

@@ -395,15 +395,19 @@ private void ConfigureDashboardHealthCheck()
             var dashboardOptions = sp.GetRequiredService<IOptions<DashboardOptions>>().Value;
             if (StringUtils.TryGetUriFromDelimitedString(dashboardOptions.DashboardUrl, ";", out var firstDashboardUrl))
             {
-                return firstDashboardUrl;
+                // Health checks to the dashboard should go to the /health endpoint. This endpoint allows anonymous requests.
+                // Sending a request to other dashboard endpoints triggered auth, which the request fails, and is redirected to the login page.
+                var uriBuilder = new UriBuilder(firstDashboardUrl);
+                uriBuilder.Path = "/health";
+                return uriBuilder.Uri;
             }
             else
             {
                 throw new DistributedApplicationException($"The dashboard resource '{KnownResourceNames.AspireDashboard}' does not have endpoints.");
             }
-        }, KnownHealthCheckNames.DasboardHealthCheck);
+        }, KnownHealthCheckNames.DashboardHealthCheck);
 
-        _innerBuilder.Services.SuppressHealthCheckHttpClientLogging(KnownHealthCheckNames.DasboardHealthCheck);
+        _innerBuilder.Services.SuppressHealthCheckHttpClientLogging(KnownHealthCheckNames.DashboardHealthCheck);
     }
 
     private void ConfigureHealthChecks()

src/Shared/KnownHealthCheckNames.cs

@@ -8,5 +8,5 @@ internal static class KnownHealthCheckNames
     /// <summary>
     /// Common name for dashboard health check.
     /// </summary>
-    public const string DasboardHealthCheck = "aspire_dashboard_check";
+    public const string DashboardHealthCheck = "aspire_dashboard_check";
 }

tests/Aspire.Dashboard.Tests/Integration/HealthTests.cs

@@ -0,0 +1,39 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Aspire.Dashboard.Utils;
+using Microsoft.AspNetCore.InternalTesting;
+using System.Net;
+using Xunit;
+
+namespace Aspire.Dashboard.Tests.Integration;
+
+public class HealthTests(ITestOutputHelper testOutputHelper)
+{
+    [Fact]
+    public async Task HealthEndpoint_SendRequest_200Response()
+    {
+        // Arrange
+        await using var app = IntegrationTestHelpers.CreateDashboardWebApplication(testOutputHelper);
+        await app.StartAsync().DefaultTimeout();
+
+        await MakeRequestAndAssert($"http://{app.FrontendSingleEndPointAccessor().EndPoint}", HttpVersion.Version11).DefaultTimeout();
+        await MakeRequestAndAssert($"http://{app.OtlpServiceHttpEndPointAccessor().EndPoint}", HttpVersion.Version11).DefaultTimeout();
+        await MakeRequestAndAssert($"http://{app.OtlpServiceGrpcEndPointAccessor().EndPoint}", HttpVersion.Version20).DefaultTimeout();
+
+        static async Task MakeRequestAndAssert(string basePath, Version httpVersion)
+        {
+            using var httpClientHandler = new HttpClientHandler { AllowAutoRedirect = false };
+            using var client = new HttpClient(httpClientHandler) { BaseAddress = new Uri(basePath) };
+
+            // Act
+            var request = new HttpRequestMessage(HttpMethod.Get, $"/{DashboardUrls.HealthBasePath}");
+            request.Version = httpVersion;
+            request.VersionPolicy = HttpVersionPolicy.RequestVersionExact;
+            var response = await client.SendAsync(request).DefaultTimeout();
+
+            // Assert 
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        }
+    }
+}