Initial beta release

src/AzureFunctionHealthCheck/AzureFunctionHealthCheck-old/AzureFunctionHealthCheck.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net5.0</TargetFramework>
+    <AssemblyName>TaleLearnCode.AzureFunctionHealthCheck</AssemblyName>
+    <RootNamespace>TaleLearnCode.AzureFunctionHealthCheck</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks" Version="5.0.5" />
+  </ItemGroup>
+
+</Project>

src/AzureFunctionHealthCheck/AzureFunctionHealthCheck-old/DefaultHealthCheckService.cs

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+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace TaleLearnCode.AzureFunctionHealthCheck
+{
+
+	public class DefaultHealthCheckService : HealthCheckService
+	{
+
+		private readonly IServiceScopeFactory _serviceScopeFactory;
+		private readonly IOptions<HealthCheckServiceOptions> _options;
+		private readonly ILogger<DefaultHealthCheckService> _logger;
+
+		public DefaultHealthCheckService(
+			IServiceScopeFactory serviceScopeFactory,
+			IOptions<HealthCheckServiceOptions> options,
+			ILogger<DefaultHealthCheckService> logger)
+		{
+			_serviceScopeFactory = serviceScopeFactory ?? throw new ArgumentNullException(nameof(serviceScopeFactory));
+			_options = options ?? throw new ArgumentNullException(nameof(options));
+			_logger = logger ?? throw new ArgumentNullException(nameof(options));
+			ValidateRegistrations(_options.Value.Registrations);
+		}
+
+		/// <summary>
+		/// Performs the health check.
+		/// </summary>
+		/// <param name="predicate">The predicate.</param>
+		/// <param name="cancellationToken">The cancellation token.</param>
+		/// <returns></returns>
+		public override async Task<HealthReport> CheckHealthAsync(
+			Func<HealthCheckRegistration, bool> predicate,
+			CancellationToken cancellationToken = default)
+		{
+
+			ICollection<HealthCheckRegistration> registrations = _options.Value.Registrations;
+
+			using IServiceScope scope = _serviceScopeFactory.CreateScope();
+
+			HealthCheckContext healthCheckContext = new();
+			Dictionary<string, HealthReportEntry> entries = new(StringComparer.OrdinalIgnoreCase);
+
+			ValueStopwatch totalTime = ValueStopwatch.StartNew();
+			Log.HealthCheckProcessingBegin(_logger);
+
+			foreach (HealthCheckRegistration registration in registrations)
+			{
+				if (predicate != null && !predicate(registration))
+					continue;
+
+				cancellationToken.ThrowIfCancellationRequested();
+
+				IHealthCheck healthCheck = registration.Factory(scope.ServiceProvider);
+
+				ValueStopwatch stopwatch = ValueStopwatch.StartNew();
+				healthCheckContext.Registration = registration;
+
+				Log.HealthCheckBegin(_logger, registration);
+
+				HealthReportEntry entry;
+				try
+				{
+					HealthCheckResult result = await healthCheck.CheckHealthAsync(healthCheckContext, cancellationToken);
+					TimeSpan duration = stopwatch.Elapsed;
+
+					entry = new HealthReportEntry(
+						status: result.Status,
+						description: result.Description,
+						duration: duration,
+						exception: result.Exception,
+						data: result.Data);
+
+					Log.HealthCheckEnd(_logger, registration, entry, duration);
+					Log.HealthCheckData(_logger, registration, entry);
+				}
+				catch (Exception ex) when (ex as OperationCanceledException == null)
+				{
+					var duration = stopwatch.Elapsed;
+					entry = new HealthReportEntry(
+						status: HealthStatus.Unhealthy,
+						description: ex.Message,
+						duration: duration,
+						exception: ex,
+						data: null);
+
+					Log.HealthCheckError(_logger, registration, ex, duration);
+				}
+				entries[registration.Name] = entry;
+			}
+
+			var totalElapsedTime = totalTime.Elapsed;
+			var report = new HealthReport(entries, totalElapsedTime);
+			Log.HealthCheckProcessingEnd(_logger, report.Status, totalElapsedTime);
+			return report;
+
+		}
+
+		private static void ValidateRegistrations(IEnumerable<HealthCheckRegistration> registrations)
+		{
+
+			List<string> duplicateNames = registrations
+				.GroupBy(c => c.Name, StringComparer.OrdinalIgnoreCase)
+				.Where(g => g.Count() > 1)
+				.Select(g => g.Key)
+				.ToList();
+
+			if (duplicateNames.Any())
+				throw new ArgumentException($"Duplicate health checks were registered with the name(s): {string.Join(", ", duplicateNames)}", nameof(registrations));
+
+		}
+
+	}
+
+}

src/AzureFunctionHealthCheck/AzureFunctionHealthCheck-old/EventIds.cs

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+using Microsoft.Extensions.Logging;
+
+namespace TaleLearnCode.AzureFunctionHealthCheck
+{
+	internal static class EventIds
+	{
+		public static readonly EventId HealthCheckProcessingBegin = new EventId(100, "HealthCheckProcessingBegin");
+		public static readonly EventId HealthCheckProcessingEnd = new EventId(101, "HealthCheckProcessingEnd");
+		public static readonly EventId HealthCheckBegin = new EventId(102, "HealthCheckBegin");
+		public static readonly EventId HealthCheckEnd = new EventId(103, "HealthCheckEnd");
+		public static readonly EventId HealthCheckError = new EventId(104, "HealthCheckError");
+		public static readonly EventId HealthCheckData = new EventId(105, "HealthCheckData");
+	}
+}

src/AzureFunctionHealthCheck/AzureFunctionHealthCheck-old/HealthCheckDataLogValue.cs

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+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace TaleLearnCode.AzureFunctionHealthCheck
+{
+
+	/// <summary>
+	/// Represents value of a health check data log.
+	/// </summary>
+	/// <seealso cref="IReadOnlyList{KeyValuePair{string, object}}" />
+	internal class HealthCheckDataLogValue : IReadOnlyList<KeyValuePair<string, object>>
+	{
+		private readonly string _name;
+		private readonly List<KeyValuePair<string, object>> _values;
+		private string _formatted;
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="HealthCheckDataLogValue"/> class.
+		/// </summary>
+		/// <param name="name">The name.</param>
+		/// <param name="values">The values.</param>
+		public HealthCheckDataLogValue(string name, IReadOnlyDictionary<string, object> values)
+		{
+			_name = name;
+			_values = values.ToList();
+			_values.Add(new KeyValuePair<string, object>("HealthCheckName", name));
+		}
+
+		/// <summary>
+		/// Gets the <see cref="KeyValuePair{string, Object}"/> at the specified index.
+		/// </summary>
+		/// <value>
+		/// The <see cref="KeyValuePair{String, Object}"/>.
+		/// </value>
+		/// <param name="index">The index.</param>
+		/// <returns></returns>
+		/// <exception cref="IndexOutOfRangeException">index</exception>
+		public KeyValuePair<string, object> this[int index]
+		{
+			get
+			{
+				if (index < 0 || index >= Count)
+					throw new IndexOutOfRangeException(nameof(index));
+				return _values[index];
+			}
+		}
+
+		public int Count => _values.Count;
+
+		/// <summary>
+		/// Returns an enumerator that iterates through the collection.
+		/// </summary>
+		/// <returns>
+		/// An enumerator that can be used to iterate through the collection.
+		/// </returns>
+		public IEnumerator<KeyValuePair<string, object>> GetEnumerator()
+		{
+			return _values.GetEnumerator();
+		}
+
+		/// <summary>
+		/// Returns an enumerator that iterates through a collection.
+		/// </summary>
+		/// <returns>
+		/// An <see cref="T:System.Collections.IEnumerator" /> object that can be used to iterate through the collection.
+		/// </returns>
+		IEnumerator IEnumerable.GetEnumerator()
+		{
+			return _values.GetEnumerator();
+		}
+
+		/// <summary>
+		/// Converts the <see cref="HealthCheckDataLogValue"/> to a string.
+		/// </summary>
+		/// <returns>
+		/// A <see cref="String" /> that represents this instance.
+		/// </returns>
+		public override string ToString()
+		{
+			if (_formatted == null)
+			{
+				var builder = new StringBuilder();
+				builder.AppendLine($"Health check data for {_name}:");
+
+				var values = _values;
+				for (var i = 0; i < values.Count; i++)
+				{
+					var kvp = values[i];
+					builder.Append("    ");
+					builder.Append(kvp.Key);
+					builder.Append(": ");
+
+					builder.AppendLine(kvp.Value?.ToString());
+				}
+
+				_formatted = builder.ToString();
+			}
+
+			return _formatted;
+		}
+
+	}
+
+}

src/AzureFunctionHealthCheck/AzureFunctionHealthCheck-old/HealthCheckServiceFunctionExtension.cs

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+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace TaleLearnCode.AzureFunctionHealthCheck
+{
+
+	/// <summary>
+	/// Provides extension methods for registering <see cref="HealthCheckService"/>.
+	/// </summary>
+	public static class HealthCheckServiceFunctionExtension
+	{
+
+		/// <summary>
+		/// Adds the <see cref="HealthCheckService"/> to the container, using the provided delegates to register.
+		/// </summary>
+		/// <param name="services">The services.</param>
+		public static IHealthChecksBuilder AddFunctionHealthChecks(this IServiceCollection services)
+		{
+			services.TryAddSingleton<HealthCheckService, DefaultHealthCheckService>();
+			return new HealthChecksBuilder(services);
+		}
+
+	}
+}

src/AzureFunctionHealthCheck/AzureFunctionHealthCheck-old/HealthChecksBuilder.cs

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+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using System;
+
+namespace TaleLearnCode.AzureFunctionHealthCheck
+{
+
+	/// <summary>
+	/// A builder used to register health checks.
+	/// </summary>
+	/// <seealso cref="IHealthChecksBuilder" />
+	public class HealthChecksBuilder : IHealthChecksBuilder
+	{
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="HealthChecksBuilder"/> class.
+		/// </summary>
+		/// <param name="services">The <see cref="T:Microsoft.Extensions.DependencyInjection.IServiceCollection" /> into which <see cref="T:Microsoft.Extensions.Diagnostics.HealthChecks.IHealthCheck" /> instances should be registered.</param>
+		public HealthChecksBuilder(IServiceCollection services)
+		{
+			Services = services;
+		}
+
+		/// <summary>
+		/// Gets the <see cref="T:Microsoft.Extensions.DependencyInjection.IServiceCollection" /> into which <see cref="T:Microsoft.Extensions.Diagnostics.HealthChecks.IHealthCheck" /> instances should be registered.
+		/// </summary>
+		public IServiceCollection Services { get; }
+
+		/// <summary>
+		/// Adds a <see cref="T:Microsoft.Extensions.Diagnostics.HealthChecks.HealthCheckRegistration" /> for a health check.
+		/// </summary>
+		/// <param name="registration">The <see cref="T:Microsoft.Extensions.Diagnostics.HealthChecks.HealthCheckRegistration" />.</param>
+		/// <returns>An initialized <see cref="HealthChecksBuilder"/></returns>
+		/// <exception cref="ArgumentNullException">registration</exception>
+		public IHealthChecksBuilder Add(HealthCheckRegistration registration)
+		{
+			if (registration == default) throw new ArgumentNullException(nameof(registration));
+			Services.Configure<HealthCheckServiceOptions>(options =>
+			{
+				options.Registrations.Add(registration);
+			});
+			return this;
+		}
+
+	}
+
+}