Work on probes and health checks. (#4042)

- Introduce probe functionality. Basic abstractions and k8s
implementation.

- Streamline the APIs for health checks by removing needless overloads.

- Rename the HealthChecks.Core package to HealthChecks.Common

Co-authored-by: Martin Taillefer <mataille@microsoft.com>

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Core/ApplicationLifecycleHealthCheck.cs → src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/ApplicationLifecycleHealthCheck.cs

@@ -14,7 +14,9 @@ namespace Microsoft.Extensions.Diagnostics.HealthChecks;
 internal sealed class ApplicationLifecycleHealthCheck : IHealthCheck
 {
     private static readonly Task<HealthCheckResult> _healthy = Task.FromResult(HealthCheckResult.Healthy());
-    private static readonly Task<HealthCheckResult> _unhealthy = Task.FromResult(HealthCheckResult.Unhealthy());
+    private static readonly Task<HealthCheckResult> _unhealthyNotStarted = Task.FromResult(HealthCheckResult.Unhealthy("Not Started"));
+    private static readonly Task<HealthCheckResult> _unhealthyStopping = Task.FromResult(HealthCheckResult.Unhealthy("Stopping"));
+    private static readonly Task<HealthCheckResult> _unhealthyStopped = Task.FromResult(HealthCheckResult.Unhealthy("Stopped"));
     private readonly IHostApplicationLifetime _appLifetime;
 
     /// <summary>
@@ -42,9 +44,23 @@ public ApplicationLifecycleHealthCheck(IHostApplicationLifetime appLifetime)
     public Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
     {
         bool isStarted = _appLifetime.ApplicationStarted.IsCancellationRequested;
+        if (!isStarted)
+        {
+            return _unhealthyNotStarted;
+        }
+
         bool isStopping = _appLifetime.ApplicationStopping.IsCancellationRequested;
+        if (isStopping)
+        {
+            return _unhealthyStopping;
+        }
+
         bool isStopped = _appLifetime.ApplicationStopped.IsCancellationRequested;
-        bool isHealthy = isStarted && !isStopping && !isStopped;
-        return isHealthy ? _healthy : _unhealthy;
+        if (isStopped)
+        {
+            return _unhealthyStopped;
+        }
+
+        return _healthy;
     }
 }

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Core/CoreHealthChecksExtensions.ApplicationLifecycle.cs → src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/CommonHealthChecksExtensions.ApplicationLifecycle.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Diagnostics.CodeAnalysis;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Shared.Diagnostics;
 
@@ -12,28 +11,17 @@ namespace Microsoft.Extensions.Diagnostics.HealthChecks;
 /// <summary>
 /// Controls various health check features.
 /// </summary>
-public static partial class CoreHealthChecksExtensions
+public static partial class CommonHealthChecksExtensions
 {
-    /// <summary>
-    /// Registers a health check provider that's tied to the application's lifecycle.
-    /// </summary>
-    /// <param name="builder">The builder to add the provider to.</param>
-    /// <returns>The value of <paramref name="builder"/>.</returns>
-    /// <exception cref="ArgumentNullException">If <paramref name="builder" /> is <see langword="null" />.</exception>
-    public static IHealthChecksBuilder AddApplicationLifecycleHealthCheck(this IHealthChecksBuilder builder)
-        => Throw.IfNull(builder)
-            .AddCheck<ApplicationLifecycleHealthCheck>("ApplicationLifecycleHealthCheck");
-
     /// <summary>
     /// Registers a health check provider that's tied to the application's lifecycle.
     /// </summary>
     /// <param name="builder">The builder to add the provider to.</param>
     /// <param name="tags">A list of tags that can be used to filter health checks.</param>
     /// <returns>The value of <paramref name="builder"/>.</returns>
-    [Experimental]
     public static IHealthChecksBuilder AddApplicationLifecycleHealthCheck(this IHealthChecksBuilder builder, params string[] tags)
         => Throw.IfNull(builder)
-            .AddCheck<ApplicationLifecycleHealthCheck>("ApplicationLifecycleHealthCheck", tags: Throw.IfNull(tags));
+            .AddCheck<ApplicationLifecycleHealthCheck>("ApplicationLifecycle", tags: Throw.IfNull(tags));
 
     /// <summary>
     /// Registers a health check provider that's tied to the application's lifecycle.
@@ -44,5 +32,5 @@ public static IHealthChecksBuilder AddApplicationLifecycleHealthCheck(this IHeal
     /// <exception cref="ArgumentNullException">If <paramref name="builder" /> or <paramref name="tags"/> are <see langword="null" />.</exception>
     public static IHealthChecksBuilder AddApplicationLifecycleHealthCheck(this IHealthChecksBuilder builder, IEnumerable<string> tags)
         => Throw.IfNull(builder)
-            .AddCheck<ApplicationLifecycleHealthCheck>("ApplicationLifecycleHealthCheck", tags: Throw.IfNull(tags));
+            .AddCheck<ApplicationLifecycleHealthCheck>("ApplicationLifecycle", tags: Throw.IfNull(tags));
 }

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Core/CoreHealthChecksExtensions.Manual.cs → src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/CommonHealthChecksExtensions.Manual.cs

@@ -8,19 +8,8 @@
 
 namespace Microsoft.Extensions.Diagnostics.HealthChecks;
 
-public static partial class CoreHealthChecksExtensions
+public static partial class CommonHealthChecksExtensions
 {
-    /// <summary>
-    /// Registers a health check provider that enables manual control of the application's health.
-    /// </summary>
-    /// <param name="builder">The builder to add the provider to.</param>
-    /// <returns>The value of <paramref name="builder"/>.</returns>
-    /// <exception cref="ArgumentNullException">If <paramref name="builder" /> is <see langword="null" />.</exception>
-    public static IHealthChecksBuilder AddManualHealthCheck(this IHealthChecksBuilder builder)
-        => Throw.IfNull(builder)
-            .AddManualHealthCheckDependencies()
-            .AddCheck<ManualHealthCheckService>("ManualHealthCheck");
-
     /// <summary>
     /// Registers a health check provider that enables manual control of the application's health.
     /// </summary>
@@ -31,7 +20,7 @@ public static IHealthChecksBuilder AddManualHealthCheck(this IHealthChecksBuilde
     public static IHealthChecksBuilder AddManualHealthCheck(this IHealthChecksBuilder builder, params string[] tags)
         => Throw.IfNull(builder)
             .AddManualHealthCheckDependencies()
-            .AddCheck<ManualHealthCheckService>("ManualHealthCheck", tags: Throw.IfNull(tags));
+            .AddCheck<ManualHealthCheckService>("Manual", tags: Throw.IfNull(tags));
 
     /// <summary>
     /// Registers a health check provider that enables manual control of the application's health.
@@ -43,7 +32,7 @@ public static IHealthChecksBuilder AddManualHealthCheck(this IHealthChecksBuilde
     public static IHealthChecksBuilder AddManualHealthCheck(this IHealthChecksBuilder builder, IEnumerable<string> tags)
         => Throw.IfNull(builder)
             .AddManualHealthCheckDependencies()
-            .AddCheck<ManualHealthCheckService>("ManualHealthCheck", tags: Throw.IfNull(tags));
+            .AddCheck<ManualHealthCheckService>("Manual", tags: Throw.IfNull(tags));
 
     /// <summary>
     /// Sets the manual health check to the healthy state.
@@ -63,8 +52,8 @@ public static void ReportUnhealthy(this IManualHealthCheck manualHealthCheck, st
         => Throw.IfNull(manualHealthCheck).Result = HealthCheckResult.Unhealthy(Throw.IfNullOrWhitespace(reason));
 
     private static IHealthChecksBuilder AddManualHealthCheckDependencies(this IHealthChecksBuilder builder)
-        => builder
-            .Services.AddSingleton<IManualHealthCheckTracker, ManualHealthCheckTracker>()
+        => builder.Services
+            .AddSingleton<ManualHealthCheckTracker>()
             .AddTransient(typeof(IManualHealthCheck<>), typeof(ManualHealthCheck<>))
             .AddHealthChecks();
 }

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Core/CoreHealthChecksExtensions.TelemetryPublisher.cs → src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/CommonHealthChecksExtensions.TelemetryPublisher.cs

@@ -10,7 +10,7 @@
 
 namespace Microsoft.Extensions.Diagnostics.HealthChecks;
 
-public static partial class CoreHealthChecksExtensions
+public static partial class CommonHealthChecksExtensions
 {
     /// <summary>
     /// Registers a health check publisher which emits telemetry representing the application's health.

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Core/ManualHealthCheck.cs → src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/ManualHealthCheck.cs

@@ -30,10 +30,10 @@ public HealthCheckResult Result
         }
     }
 
-    private readonly IManualHealthCheckTracker _tracker;
+    private readonly ManualHealthCheckTracker _tracker;
 
     [SuppressMessage("Major Code Smell", "S3366:\"this\" should not be exposed from constructors", Justification = "It's OK, just registering into a list")]
-    public ManualHealthCheck(IManualHealthCheckTracker tracker)
+    public ManualHealthCheck(ManualHealthCheckTracker tracker)
     {
         Result = HealthCheckResult.Unhealthy("Initial state");
 

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Core/ManualHealthCheckService.cs → src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/ManualHealthCheckService.cs

@@ -14,9 +14,9 @@ namespace Microsoft.Extensions.Diagnostics.HealthChecks;
 /// </remarks>
 internal sealed class ManualHealthCheckService : IHealthCheck
 {
-    private readonly IManualHealthCheckTracker _tracker;
+    private readonly ManualHealthCheckTracker _tracker;
 
-    public ManualHealthCheckService(IManualHealthCheckTracker tracker)
+    public ManualHealthCheckService(ManualHealthCheckTracker tracker)
     {
         _tracker = tracker;
     }

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Core/ManualHealthCheckTracker.cs → src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/ManualHealthCheckTracker.cs

@@ -8,13 +8,12 @@
 
 namespace Microsoft.Extensions.Diagnostics.HealthChecks;
 
-internal sealed class ManualHealthCheckTracker : IManualHealthCheckTracker
+internal sealed class ManualHealthCheckTracker
 {
     private static readonly HealthCheckResult _healthy = HealthCheckResult.Healthy();
 
     private readonly ConcurrentDictionary<IManualHealthCheck, bool> _checks = new();
 
-    /// <inheritdoc />
     public void Register(IManualHealthCheck check)
     {
         _ = _checks.AddOrUpdate(check, true, (_, _) => true);
@@ -25,7 +24,6 @@ public void Unregister(IManualHealthCheck checkToRemove)
         _ = _checks.TryRemove(checkToRemove, out _);
     }
 
-    /// <inheritdoc />
     public HealthCheckResult GetHealthCheckResult()
     {
         // Construct string showing all reasons for unhealthy manual health checks

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/Microsoft.Extensions.Diagnostics.HealthChecks.Common.json

@@ -0,0 +1,77 @@
+{
+  "Name": "Microsoft.Extensions.Diagnostics.HealthChecks.Common, Version=8.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35",
+  "Types": [
+    {
+      "Type": "static class Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions",
+      "Stage": "Stable",
+      "Methods": [
+        {
+          "Member": "static Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.AddApplicationLifecycleHealthCheck(this Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder builder, params string[] tags);",
+          "Stage": "Stable"
+        },
+        {
+          "Member": "static Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.AddApplicationLifecycleHealthCheck(this Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder builder, System.Collections.Generic.IEnumerable<string> tags);",
+          "Stage": "Stable"
+        },
+        {
+          "Member": "static Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.AddManualHealthCheck(this Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder builder, params string[] tags);",
+          "Stage": "Stable"
+        },
+        {
+          "Member": "static Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.AddManualHealthCheck(this Microsoft.Extensions.DependencyInjection.IHealthChecksBuilder builder, System.Collections.Generic.IEnumerable<string> tags);",
+          "Stage": "Stable"
+        },
+        {
+          "Member": "static Microsoft.Extensions.DependencyInjection.IServiceCollection Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.AddTelemetryHealthCheckPublisher(this Microsoft.Extensions.DependencyInjection.IServiceCollection services);",
+          "Stage": "Stable"
+        },
+        {
+          "Member": "static Microsoft.Extensions.DependencyInjection.IServiceCollection Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.AddTelemetryHealthCheckPublisher(this Microsoft.Extensions.DependencyInjection.IServiceCollection services, Microsoft.Extensions.Configuration.IConfigurationSection section);",
+          "Stage": "Experimental"
+        },
+        {
+          "Member": "static Microsoft.Extensions.DependencyInjection.IServiceCollection Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.AddTelemetryHealthCheckPublisher(this Microsoft.Extensions.DependencyInjection.IServiceCollection services, System.Action<Microsoft.Extensions.Diagnostics.HealthChecks.TelemetryHealthCheckPublisherOptions> configure);",
+          "Stage": "Experimental"
+        },
+        {
+          "Member": "static void Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.ReportHealthy(this Microsoft.Extensions.Diagnostics.HealthChecks.IManualHealthCheck manualHealthCheck);",
+          "Stage": "Stable"
+        },
+        {
+          "Member": "static void Microsoft.Extensions.Diagnostics.HealthChecks.CommonHealthChecksExtensions.ReportUnhealthy(this Microsoft.Extensions.Diagnostics.HealthChecks.IManualHealthCheck manualHealthCheck, string reason);",
+          "Stage": "Stable"
+        }
+      ]
+    },
+    {
+      "Type": "interface Microsoft.Extensions.Diagnostics.HealthChecks.IManualHealthCheck : System.IDisposable",
+      "Stage": "Stable",
+      "Properties": [
+        {
+          "Member": "Microsoft.Extensions.Diagnostics.HealthChecks.HealthCheckResult Microsoft.Extensions.Diagnostics.HealthChecks.IManualHealthCheck.Result { get; set; }",
+          "Stage": "Stable"
+        }
+      ]
+    },
+    {
+      "Type": "interface Microsoft.Extensions.Diagnostics.HealthChecks.IManualHealthCheck<T> : Microsoft.Extensions.Diagnostics.HealthChecks.IManualHealthCheck, System.IDisposable",
+      "Stage": "Stable"
+    },
+    {
+      "Type": "class Microsoft.Extensions.Diagnostics.HealthChecks.TelemetryHealthCheckPublisherOptions",
+      "Stage": "Experimental",
+      "Methods": [
+        {
+          "Member": "Microsoft.Extensions.Diagnostics.HealthChecks.TelemetryHealthCheckPublisherOptions.TelemetryHealthCheckPublisherOptions();",
+          "Stage": "Experimental"
+        }
+      ],
+      "Properties": [
+        {
+          "Member": "bool Microsoft.Extensions.Diagnostics.HealthChecks.TelemetryHealthCheckPublisherOptions.LogOnlyUnhealthy { get; set; }",
+          "Stage": "Experimental"
+        }
+      ]
+    }
+  ]
+}

src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Core/TelemetryHealthCheckPublisherOptions.cs → src/Libraries/Microsoft.Extensions.Diagnostics.HealthChecks.Common/TelemetryHealthCheckPublisherOptions.cs

@@ -17,6 +17,5 @@ public class TelemetryHealthCheckPublisherOptions
     /// <remarks>
     /// Default set to false.
     /// </remarks>
-    [Experimental]
     public bool LogOnlyUnhealthy { get; set; }
 }