Move validation of HealthCheckServiceOptions

src/HealthChecks/HealthChecks/src/DefaultHealthCheckService.cs

@@ -18,7 +18,7 @@ namespace Microsoft.Extensions.Diagnostics.HealthChecks
     internal class DefaultHealthCheckService : HealthCheckService
     {
         private readonly IServiceScopeFactory _scopeFactory;
-        private readonly IOptions<HealthCheckServiceOptions> _options;
+        private readonly HealthCheckServiceOptions _options;
         private readonly ILogger<DefaultHealthCheckService> _logger;
 
         public DefaultHealthCheckService(
@@ -27,19 +27,18 @@ public DefaultHealthCheckService(
             ILogger<DefaultHealthCheckService> logger)
         {
             _scopeFactory = scopeFactory ?? throw new ArgumentNullException(nameof(scopeFactory));
-            _options = options ?? throw new ArgumentNullException(nameof(options));
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
-
             // We're specifically going out of our way to do this at startup time. We want to make sure you
             // get any kind of health-check related error as early as possible. Waiting until someone
             // actually tries to **run** health checks would be real baaaaad.
-            ValidateRegistrations(_options.Value.Registrations);
+            _options = options?.Value ?? throw new ArgumentNullException(nameof(options));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
         }
+
         public override async Task<HealthReport> CheckHealthAsync(
             Func<HealthCheckRegistration, bool>? predicate,
             CancellationToken cancellationToken = default)
         {
-            var registrations = _options.Value.Registrations;
+            var registrations = _options.Registrations;
             if (predicate != null)
             {
                 registrations = registrations.Where(predicate).ToArray();
@@ -155,21 +154,6 @@ private async Task<HealthReportEntry> RunCheckAsync(IServiceScope scope, HealthC
             }
         }
 
-        private static void ValidateRegistrations(IEnumerable<HealthCheckRegistration> registrations)
-        {
-            // Scan the list for duplicate names to provide a better error if there are duplicates.
-            var duplicateNames = registrations
-                .GroupBy(c => c.Name, StringComparer.OrdinalIgnoreCase)
-                .Where(g => g.Count() > 1)
-                .Select(g => g.Key)
-                .ToList();
-
-            if (duplicateNames.Count > 0)
-            {
-                throw new ArgumentException($"Duplicate health checks were registered with the name(s): {string.Join(", ", duplicateNames)}", nameof(registrations));
-            }
-        }
-
         internal static class EventIds
         {
             public static readonly EventId HealthCheckProcessingBegin = new EventId(100, "HealthCheckProcessingBegin");

src/HealthChecks/HealthChecks/src/DependencyInjection/HealthCheckServiceCollectionExtensions.cs

@@ -3,7 +3,9 @@
 
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Diagnostics.HealthChecks;
+using Microsoft.Extensions.Diagnostics.HealthChecks.DependencyInjection;
 using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Options;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
@@ -25,6 +27,7 @@ public static class HealthCheckServiceCollectionExtensions
         /// <returns>An instance of <see cref="IHealthChecksBuilder"/> from which health checks can be registered.</returns>
         public static IHealthChecksBuilder AddHealthChecks(this IServiceCollection services)
         {
+            services.TryAddEnumerable(ServiceDescriptor.Transient<IValidateOptions<HealthCheckServiceOptions>, HealthCheckServiceOptionsValidation>());
             services.TryAddSingleton<HealthCheckService, DefaultHealthCheckService>();
             services.TryAddEnumerable(ServiceDescriptor.Singleton<IHostedService, HealthCheckPublisherHostedService>());
             return new HealthChecksBuilder(services);

src/HealthChecks/HealthChecks/src/DependencyInjection/HealthCheckServiceOptionsValidation.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Linq;
+using Microsoft.Extensions.Options;
+
+namespace Microsoft.Extensions.Diagnostics.HealthChecks.DependencyInjection
+{
+    internal class HealthCheckServiceOptionsValidation : IValidateOptions<HealthCheckServiceOptions>
+    {
+        public ValidateOptionsResult Validate(string name, HealthCheckServiceOptions options)
+        {
+            // Scan the list for duplicate names to provide a better error if there are duplicates.
+            var duplicateNames = options.Registrations
+                .GroupBy(c => c.Name, StringComparer.OrdinalIgnoreCase)
+                .Where(g => g.Count() > 1)
+                .Select(g => g.Key)
+                .ToList();
+
+            if (duplicateNames.Count > 0)
+            {
+                return ValidateOptionsResult.Fail($"Duplicate health checks were registered with the name(s): {string.Join(", ", duplicateNames)}");
+            }
+
+            return ValidateOptionsResult.Success;
+        }
+    }
+}

src/HealthChecks/HealthChecks/test/DefaultHealthCheckServiceTest.cs

@@ -39,12 +39,8 @@ public void Constructor_ThrowsUsefulExceptionForDuplicateNames()
 
             var services = serviceCollection.BuildServiceProvider();
 
-            var scopeFactory = services.GetRequiredService<IServiceScopeFactory>();
-            var options = services.GetRequiredService<IOptions<HealthCheckServiceOptions>>();
-            var logger = services.GetRequiredService<ILogger<DefaultHealthCheckService>>();
-
             // Act
-            var exception = Assert.Throws<ArgumentException>(() => new DefaultHealthCheckService(scopeFactory, options, logger));
+            var exception = Assert.Throws<OptionsValidationException>(() => services.GetRequiredService<HealthCheckService>());
 
             // Assert
             Assert.StartsWith($"Duplicate health checks were registered with the name(s): Foo, Baz", exception.Message);